Adler, Paul (USDA-ARS, Building 3702, Curtin Road, University Park, PA, 16802-3702; Phone: 814-865-8894; Fax: 814-863-0935; Email: paul.adler@ars.usda.gov)
Climate Change Effects on Greenhouse Gas Emissions From
Bioenergy Cropping Systems in
P.R. Adler*, S.J. Del Grosso,
W.J. Parton
Reducing the net global warming potential (GWP) of energy use is a major factor driving interest in biofuels. Bioenergy cropping systems vary in contribution to the GWP due to the crop yield and resulting quantity of fossil fuels displaced, quantity and quality of C added to the soil, feedstock conversion efficiency, N2O emissions, N use efficiency, and inputs required for crop production and operation of farm machinery. The objective of the study was to use DAYCENT to model the impact of climate change on net greenhouse gas (GHG) emissions of bioenergy cropping systems (corn, soybeans, alfalfa, switchgrass, reed canarygrass, and hybrid poplar) in Pennsylvania for inclusion in a full C cycle analysis. Weather data driving climate change scenarios were from VEMAP for the no change in climate scenario and from the Canadian Centre for Climate Modeling and Analysis (CGCM1model) and Hadley Centre for Climate Prediction and Research, UK (HADCM2 model) for the climate change simulations where CO2 was assumed to double from 2004 - 2100. Without additional N, there was little response of nonleguminous crops to climate change. Alfalfa yields nearly doubled without additional N, whereas the yields of soybean were mixed depending on climate model. When the rate of N application increased 4% per year in the climate change simulations, corn, reed canarygrass, and switchgrass yields increased. Although N loss through N2O emissions and NO3-N leaching also increased with N application, further optimization will minimize these loses. Reed canarygrass had the highest N2O emissions and NO3-N leaching followed by corn and switchgrass and then soybeans and alfalfa. The greatest increase in soil C levels occurred with switchgrass, followed by corn, soybean and reed canarygrass were about neutral, and during the alfalfa segment in the corn soybean alfalfa crop rotation, soil C decreased. The quantity of displaced fossil fuel was the largest GHG sink. Soil C sequestration was the second largest GHG sink. Although crops with higher soil C inputs, such as switchgrass and hybrid poplar, will have higher equilibrium soil C levels, the change in system C will approach zero in the long term. N2O emissions were the largest GHG source. When the credit for the amount of fossil fuel displaced was not taken into account and soil C storage was assumed to have reached its maximum capacity, switchgrass and hybrid poplar were the only cropping systems to remain a sink for GHGs. Therefore, use of switchgrass and hybrid poplar for production of biofuels has the potential to be GHG neutral and may even be a long-term sink for GHGs.
Al-Kaisi, Mahdi (Iowa State University, Department of Agronomy, 2104 Agronomy Hall, Ames, IA, 50011; Phone: 515-294-8304; Fax: 515-294-9985; Email: malkaisi@iastate.edu)
Agricultural Production Practices - Effect on Soil Carbon Dynamics and Carbon Dioxide Emission
M.M. Al-Kaisi*, M.A.Licht, X. Yin
Soil carbon change and carbon
dioxide emission due to different tillage systems need to be evaluated to
encourage the adoption of conservation practices to sustain soil productivity and
protect the environment. We hypothesize that soil carbon storage and carbon
dioxide emission respond to conservation tillage differently from conventional
tillage because of their differential effects on soil properties. This study
was conducted from 1998 through 2001 to evaluate tillage effects on soil carbon
storage and carbon dioxide emission in Clarion-Nicollet-Webster soil
association in a corn [Zea mays
L.]-soybean [Glycine max (L.) Merr.]
rotation in Iowa. Treatments included no-tillage with and without residue,
strip-tillage, deep rip, chisel plow, and moldboard plow. No-tillage with
residue and strip-tillage significantly increased total soil organic carbon and
mineral fraction carbon at the 0- to 5- and 5- to 10-cm soil depths compared
with chisel plow after 3 years of tillage practices. Soil carbon dioxide
emission was lower for less intensive tillage treatments compared with
moldboard plow, with the greatest differences occurring immediately after
tillage operations. Cumulative soil carbon dioxide emission was 19 % to 41%
lower for less intensive tillage treatments than moldboard plow, and it was 24%
less for no-tillage with residue than without residue during the 480-hour
measurement period. Estimated soil mineralizable carbon pool was reduced by 22% to 66% with less
intensive tillage treatments compared to moldboard plow. Adopting less
intensive tillage systems such as no-tillage, strip-tillage, deep rip, and
chisel plow and better crop residue cover are effective in reducing carbon
dioxide emission and thus improving soil carbon sequestration in a corn-soybean
rotation.
Albaladejo, Juan (CEBAS-CSIC,
Campus de Espinardo, Murcia, MU, 30100, Spain; Phone: ++34 968 396338; Fax:
++34 968 396213; Email: jalba@cebas.csic.es)
Carbon Fraction and C-CO2
Released in Abandoned Agricultural Soils
C. Garcia, J. Albaladejo*,
J.A. Pascual, J.L. Moreno, F. Bastida, T. Hernandez
Soil is an important natural resource that needs to be preserved. However, the need to maintain increasing levels of production have led to inappropriate soil management and the consequent loss of soil fertility. When a soil is exposed to degradative processes (for example, abandonment after intensive agricultural practices, devegetation), its biological state is the first to be affected, diminishing its productive capacity. This fact is of paramount importance since, as it is widely accepted, metabolic activity is essential to the suitable functioning of ecosystems. The microbial metabolic activity of soil is responsible for the mineralization and humification of any organic components, including recalcitrant ones, reaching the soil. One important characteristic of the soils of the Mediterranean regions is that they are indeed submitted to erosion and desertification processes and that they have a low organic matter content. Intensive cultivation, continual ploughing and forest fires, allied to years of unsuitable agricultural practices, have had an important effect on humification processes and on properties associated with degradation. All the above has led to a great diminution in the quantity of vegetal remains provided to the soil, while the humus is undergoing a process of accelerated mineralization as a result of tilling. The inevitable result is a progressive diminution of the organic matter content and the negative consequences entailed. Changes in soil organic matter and several carbon fraction in abandoned semiarid agricultural soils, at different times after abandonment in comparison with natural soils exposed to the same climate have been studied. Total organic C and water soluble C showed a decrease in the abandoned soils. The scarce quantity of plant residues in these soils can be responsible for this effect. Microbial Biomass C (MBC) can be considered to be a more sensitive indicator of soil quality than organic matter or total organic C, since it responds more rapidly and to a greater extent to changes (e.g. degradation). The value of MBC detected in the abandoned soils varied greatly. It declined when agricultural soils were abandoned and decreased with time elapsed, presumably as a consequence of the loss of the capacity to protect soils against erosion processes. Soil respiration (CO2 loss) is a good indicator of soil microbial activity. CO2 losses in all the abandoned soils were significantly lower than in natural soils, particularly in the soils abandoned for the longest period of time, the importance of the duration of abandonment on microbial activity being again demonstrated.
Albaladejo, Juan (CEBAS-CSIC,
Campus
Restoration of Desertified Lands by Organic Amendment: Medium-Term Effect on Carbon Sequestration
J. Albaladejo*, M.
Martinez-Mena, R. Ortiz, J. Lopez, V.Castillo
Soil erosion and degradation in desertification-prone areas lead to a drastic decrease in the soil potential for carbon sequestration. Restoration of degraded lands could be a way to reverse this environmental degradation process in semiarid areas and mitigation of greenhouse gases. The strategy of restoration used in this experiment starts from the hypothesis that the improvement of soil characteristics favours the growth of a spontaneous vegetal cover, stimulating de carbon cycle. The aim was to evaluate the effectiveness at medium-long term of a unique addition of organic refuse on the soil potential for carbon sequestration. An addition of 25 kg m-2 of solid urban refuse was applied, in 1988, into the top 10 cm of a 85 m-2 plot, with other plot without treatment as control. The plots are sited in an open scrubland, (2-4% cover) of desertic appearance, with 5% slope. The climate is semiarid to arid with 300mm of average total annual precipitation and 17º C annual mean temperature. The soil is a Xeric Torriorthent with high physical and biological degradation. Sixteen years later a monitoring was carried out to state the lasting of the organic addition effect on the SOC pools and soil physical characteristics improvement. The TOC contents were 9.5 g kg-1 and 16.4 g kg-1 in the control and restored plots respectively. This mean 1.42 kg m-2and 2.46 kg m-1 of OC in the control and restored plot, respectively, in the top 10cm of the soil. Thus, the land restoration led to 10.3 Mg ha-1 of C sequestration. An important pool of the sequestered C remains in the soil as recalcitrant pool. This assumption may be supported by two facts: 1) The texture is coarser in the restored plot than in the control, probably due to the increase in microaggregates clay-humus, strongly stabilized and very difficult to breakdown for chemical dispersion, and 2) The higher difference between TOC and humic substances C in the restored plot, showing that an important proportion of SOC after restoration, was incorporated into the soil as long-term stable humin. Likewise, statistically significant higher values in bulk density, saturated hydraulic conductivity and aggregate stability were displayed in the restored plot at 0-10 cm depth. Soil porosity and water retention capacity showed, as well, higher mean values in the restored plot, but without significant differences. In addition, soil erosion was strongly reduced. The ratio annual sediment in restored plot/annual sediment in control plot, range from 18.8.10-3 to 1.7.10-3 along the years. The results obtained in this experiment point out the effectiveness of restoration of eroded and degraded soils, by means of an unique addition of organic amendment, to increase the recalcitrant pool of SOC.
Allen, L. H. (USDA-ARS & Agronomy Department, University of Florida, P.O. Box –110965, Gainesville, Florida, 32611-0965; Phone: 352-392-8194; Fax: 352-392-6139; Email: LHAJR@mail.ifas.ufl.edu)
Soil Organic Carbon and Nitrogen Accumulation of Rhizoma Perennial Peanut and Bahiagrass Grown under Elevated CO2 and Temperature
L.H. Allen*, S.L. Albrecht, K.J. Boote,
J.M.G. Thomas, K.
Carbon sequestration in soils might mitigate the increase of
CO2 in the atmosphere. Rhizoma perennial peanut (RPP) and bahiagrass (BG) were grown at Gainesville, FL in field soil
plots at four temperature zones (baseline-ambient, +1.5, +3.0, and +4.5
Celsius) in temperature-gradient greenhouses at 360 and 700 ppm
CO2 from 1995 to 2000. In addition to measurements of growth and
herbage yield, soil samples from the top 20 cm of each plot were collected in
February 1995 before establishment, and before new growth began each year
thereafter, including December 2000 when the study ended. February 1995 and
December 2000 samples were analyzed for soil organic carbon (SOC) and nitrogen
(SON) for each species, CO2 concentration, and temperature. First,
across all treatments of the six-year period, SOC increased 26% and SON
increased 34%. Mean SOC increase was 1.396 and 0.746 g/kg in BG and RPP,
respectively, indicating that BG sequestered more SOC than RPP. Mean SOC gain
of BG at 700 and 360 ppm CO2 was 1.450 and
1.343 g/kg, respectively, indicating that elevated CO2 caused only a
slight increase in SOC. However, mean increase of RPP at 700 and 360 ppm CO2 was 0.949 g/kg and 0.544 g/kg,
respectively, indicating that elevated CO2 caused a significant
increase in SOC in RPP plots. No response of SOC to temperature was found in
BG, but SOC decreased with temperature in RPP plots. Growth of both forages
caused an increase in SOC, but responses to CO2 and temperature were
species dependent. Generally, SON responses were similar to SOC, but SON was
much less affected by CO2 concentration. From these data we
calculated a SOC accumulation of 540
kg/ha per year from the 6 years of data. Removing the CO2 effect
gave 425 kg/ha per year of SOC.
In 1998, from a side by side comparison of soils under continuous tillage
(winter small grain crops or fallow) and under 15-years of continuous unharvested RPP at Gainesville, FL, Allen and Nelson
(unpublished), found 370 kg/ha per year
accumulation of SOC for RPP. This is consistent with RPP accumulating less SOC
than BG. Comparing data, W.A. Albrecht (1938) reported an accumulation of 380 kg/ha per year across a 14-year
red clover study in
Amado, Telmo (Univ.of Santa Maria, Soil Departament, Federal University of
Santa Maria, Santa Maria, RS, 97105-900, Brazil, Phone: (55)2208916; Fax:
(55)2208256; Email: tamado@smail.ufsm.br)
Carbon Sequestration in No-Tillage Systems with Intensive
Use of Cover Crops in
T.J.C. Amado*
Amichev, Beyhan (Virginia
Tech ,
B.Y. Amichev*, J.A. Burger
Carbon accreditation of forest development projects is an essential approach to sequestering atmospheric C under the provisions of the Kyoto Protocol. Standard soil C accounting methods tend to largely overestimate the C contained in soil-incorporated organic matter on mined lands. This study was conducted (i) to determine the distribution pattern and variation of soil C stock down the soil profile and across space and (ii) to compare two methods of precision soil C accounting on mined land. We measured the soil C content on 9 mined sites reclaimed to pastureland in the period after the passage of Surface Mining Control and Reclamation Act of 1977 (SMCRA). Mine soil samples of the surface soil layer (topsoil) and the subsurface overburden material (mine spoil) were collected; chemical and physical soil properties were determined on the less-than-2mm fine sample fraction. Soil C stock maps were generated using common geostatistical procedures in ArcGIS 8.2® software. Our results show that the soil C variation across space was greater in the mine spoil (CV of 35% to 81%) compared to the topsoil (CV of 31% to 53%). Bulk density of the fine fraction (BD), C:N ratio (CN), coarse fragment content (CFC) and electrical conductivity (EC) explained between 54% and 91% of the variation of mine spoil C stock. Percent sandstone (SS), CN, and BD explained between 33% and 92% of the variation of topsoil C stock. The mean soil C stock computed as the average of collected soil samples was greater than that derived from the soil C stock maps. On average the C content decreased 30% for every 10 cm down the mine soil profile. There was no evident pattern in the vertical distribution of soil C most likely due to irregular alterations of soil properties down the soil profile during the many years of mine spoil weathering.
Amonette, James E (Pacific Northwest National Laboratory,
Enhancing Soil Humification: Insights from a Model System
J.E. Amonette*, J.B. Kim, C.T. Garten, C.C. Trettin, R.S. Arvidson, A. Luttge
Our research has focused on understanding the fundamental process by which humus is created (i.e., humification) and extending this knowledge to enhance the rate of humification. The rate-limiting step in the humification process appears to be the oxidation of polyphenols to quinones. These quinones then react with peptides and amino acids to form large melanin-like polymers that resist further degradation by microorganisms.
Soil fungi produce enzymes such as polyphenol oxidases and laccases that catalyze the oxidation step. Soil minerals, such as iron and manganese oxides, can also perform this function. We have observed a significant synergetic effect when a polyphenol oxidase (tyrosinase) and a mineral phase (e.g., mesoporous silica, manganese oxide, alkaline fly ash) are both present. As soil enzyme activity depends on structural conformation, and longevity depends on protection from microbial predation, we are examining the nature of enzyme attachment to soil particles and the impact of physical properties such as pore size on activity and longevity.
This presentation summarizes our laboratory results obtained using a model tyrosinase-enzyme-based reaction system. We perturbed the system by adding various co-catalysts and by changing the availability of oxygen and moisture. Our results yield insights into reaction mechanisms and suggest possible management strategies for enhancing soil-C sequestration.
We conclude that co-catalysis of humification occurs by three mechanisms involving physical stabilization of tyrosinase, direct oxidation of the monomers, and promotion of the oxidation and condensation steps by alkaline pH. Although tyrosinase activity is greatest at neutral pHs, the large pH dependence of the condensation step drives the overall reaction to maximum rates under alkaline conditions. Liming of soils to slightly alkaline pH should enhance net carbon sequestration.
Alkaline fly ash is a potential liming agent for soils, provided that the carbon costs associated with transportation from the source are less than the organic carbon that is humified. Soils that contain carbonate require flyash with relatively high-unburned C content (charcoal residual) to sustain a net positive sequestration. The porous charcoal residue provides sorption sites for the enzyme and for the organic monomers involved, which otherwise would attack and dissolve soil carbonates.
Amos, Brigid (University of Nebraska-Lincoln, 236 Kiem Hall, Dept. of Agronomy and Horticulture, Lincoln, NE, 68583-0915; Phone: 402-472-7989; Email: bamos2@unlnotes.unl.edu)
Approaches to Separating Autotrophic and Heterotrophic Contributions to Soil Respiration in Maize-Based Agroecosystems
B. Amos*, D.T. Walters, S. Madhavan, T.J. Arkebauer, D.L. Scoby
We will present two approaches to separating soil respiration into two specific sources: an autotrophic source (Ra), defined as combined root respiration and the respiration of soil microorganisms residing in the rhizosphere and deriving energy from root exudation and turnover, and a heterotrophic source (Rh), defined as the respiration of soil microorganisms and macroorganisms not directly under the influence of the live root system and deriving energy from soil organic matter. The two approaches discussed are the root exclusion technique (i.e., measuring soil respiration with and without roots) and a method in which delta 13C measurements are made of soil respiration samples collected from root-excluded and non root-excluded soil. These methods were used to separate Ra and Rh in irrigated and rainfed maize-based agroecosystems in the western USA Corn Belt. We will present preliminary results and consider the advantages and potential pitfalls of both methods.
Antinori, Camille (Lawrence Berkeley National Laboratory, Environmental Energy
Technologies Div., LBNL, One Cyclotron Road, 90-R4000, Berkeley, CA,
94720; Phone: 510-495-2277; Fax: 510-486-6996; Email: cmantinori@lbl.gov)
Transaction Costs of Project-Based Carbon Reduction: Evidence from the Forestry Sector
Camille
Antinori, Jayant Sathaye, Ken Andrasko*
Recognition of the need to address global climate change has created a new market for trading carbon emissions reductions. This paper considers whether transaction costs may hinder this market’s further growth and development. Transaction costs refer to costs beyond production required to make a trade, such as search for trading partners, contract writing and negotiation, monitoring, regulatory approval, as well as the overall risks of undertaking the project. We focus on ten projects in the forestry sector in Asia, Latin America and the US. We develop and use a common framework for categorizing transaction costs, and using project-specific data estimate costs for a nascent (i.e., current early, thin market) and a mature emissions reduction market, and with and without insurance costs. We conclude that transaction costs decline as the log of the project size, and that costs are lower in a mature compared to the current nascent market.
Arkebauer, Tim (University of Nebraska-Lincoln, 106 KCR Bldg., Department of Agronomy and Horticulture, Lincoln, NE, 685830817; Phone: 402-472-2847; 402-472-3654; Email: tja@unl.edu)
Soil Surface CO2, N2O and CH4 Fluxes and Annual Estimates of Ecosystem Respiration and Global Warming Potentials in Maize-based Agroecosystems
T.
Arkebauer*, H. Shen, D. Scoby
Recent changes in global climate have been characterized by increasing atmospheric concentrations of CO2, CH4 and N2O. Mitigation strategies include sequestering atmospheric carbon in soils. The maize-based cropping systems that dominate the Great Plains may have significant carbon sequestration potential. The primary goal of our program is to quantify ecosystem respiration and global warming potential through near-continuous year-round measurement of soil surface CO2, N2O and CH4 fluxes in the maize-based cropping systems of the Great Plains region. We are integrating the three gas fluxes over diel, seasonal and annual time scales for comparison among various treatments (e.g., maize vs. soybean, irrigated vs. rainfed). We are analyzing flux readings in terms of supporting measurements (e.g., soil temperature, soil moisture content, leaf area index, biomass) in order to elucidate the effects of relevant controlling factors. We are also focusing on scaling up single leaf respiration rates to the canopy level by drawing on seasonal LAI and leaf N content measurements in conjunction with continuously recorded canopy air temperatures. Using these data, we estimate annual ecosystem respiration and global warming potentials for each cropping system and compare results between the various systems.
Atwood, Jay (USDA-NRCS-RIAD,
808 East Blackland Road, Temple, TX, 76502; Phone: 254-770-6632; Fax:
254-770-6561; Email: jatwood@brc.tamus.edu)
Effect of the Conservation Reserve Program (CRP) on Soil Carbon
J.D. Atwood*, S.R. Potter, J.R. Williams, M.L. Norfleet
The CRP effect on the rate of cropland soil carbon (C)
storage was estimated. The analysis
included the 89.6 percent of the 32.7 million acres classified as CRP in the 1997
National Resource Inventory (NRI) for which successful model simulations could
be completed. Two scenarios were
simulated: 1) a CRP scenario reflecting management according to the 1997 NRI
and contracted CRP practices for the first 12 signup periods; and 2) a Crop
scenario that assumed the crop mix reported in the NRI preceding CRP enrollment
would have continued, but with tillage, conservation practice, and nutrient
management at 1997 levels observed on non-CRP land. Individual NRI CRP sample
points were grouped into 2,570 clusters according to climate, soil, and
landscape characteristics. For each
cluster, multiple crop simulations were defined for the diverse mix of prior
crops and tillage systems of the NRI points in the cluster and up to four CRP
simulations were defined for native grass, introduced grass, tree, and wildlife
habitat cover types. A total of 20,514
simulations were required for the Crop and CRP scenarios. The simulations were
30 years in length and were replicated for five sets of randomly generated
daily weather to remove year-to-year variation in model output due to weather
patterns rather than due to program effects.
The annual model output was divided into three periods for analysis: 1)
years 1 to 10 reflecting the duration of most CRP contracts; 2) years 11 to 20
reflecting benefits of CRP re-enrollment as contracts expire; and 3) years 21
to 30 reflecting benefits for longer term CRP easements. The CRP C benefit (C
sequestration rate) was calculated as the rate of CRP soil C storage minus the
rate of continued cropping soil C storage.
On average, the CRP C benefit was 0.90, 0.49, and 0.36 tons per acre per
year in years 1 to 10, years 11 to 20, and years 21 to 30, respectively, for
total annual C storage increases of 26.2, 14.3, and 10.6 million tons in the
three periods for the 29.3 million acres simulated. In years 1 to 10, the CRP C benefit ranged
from a low of 0.7 tons per acre per year in the Northeast to a high of 1.1 tons
per acre per year in the Upper Midwest.
Within the regions, the standard deviation of the CRP C benefit, where
the sample was the set of averages calculated by soil and climate class, varied
from 0.56 tons per acre per year in the Southern Great Plains to 1.17 tons per
acre per year in the Upper Midwest. With
continued cropping, 45 percent of the land would lose five percent or more C in
years 1 to 10; with conversion to CRP only three percent would lose more than
five percent C. With continued cropping
in years 21 to 30, the area losing more than five percent of soil C increased
to more than 48 percent. With continued cropping approximately 20 percent of
the area gained more than five percent carbon in years 1 to 10; whereas with
CRP, approximately 85 percent of the land gained more than 5 percent carbon in
the first 10 years. The percent of the
CRP land gaining more than five percent carbon was about equal at the national
level in the second and third periods, near 20 percent, implying a gradual
convergence towards new, stable, higher soil C levels sometime after the second
or third period. The estimated CRP C storage benefit varied according to
tillage method used for the continued cropping.
In years 1 to 10, the CRP C storage benefit relative to conventional,
mulch, and notill cropping systems for non-forage crops was estimated to be
1.16, 1.02, and 0.50 tons per acre per year, respectively. In years 21 to 30 the CRP C storage benefit
was nearly equal across all tillage types.
Bair, Lucas (USDA-FS, Corvallis, OR Forest Science Laboratory, 3200 SW Jefferson Way, Corvallis, OR, 97331; Phone: 541-750-7422; mail: lbair@fs.fed.us)
Projecting Private Forest Investment and Forest Carbon with the Forest and Agricultural Sector Optimization Model – Green House Gas
L.S. Bair*, R.J. Alig
Study of landowner behavior aids in designing more effective incentives for promoting activities to mitigate climate change, and owners of private timberland could play important roles in any forestry-related contributions to reducing net greenhouse gas emissions. The Forest and Agricultural Sector Optimization Model—Green House Gas version (FASOMGHG) is a dynamic, nonlinear programming model of the forest and agricultural sectors in the United States that we used to model private timberland investment behavior over a one hundred year projection. FASOMGHG is the successor to the Forest and Agricultural Sector Optimization Model (FASOM) and endogenizes timber investment, harvest, and price to simulate allocation of land over time to competing activities in both the forest and agricultural sectors and the resultant net greenhouse gas emissions. We updated the forest sector data in the FASOMGHG model to provide more specific forest type and management intensity class information. For example, the model now differentiates seven planted pine management intensity classes for the U.S. South, compared to two classes in the 1990s FASOM model. The results of the baseline scenario in FASOMGHG illustrate the potential impact of intensive management on national timber production and net greenhouse gas reductions when implemented by private timberland owners. Preliminary findings indicate that allocation of timberland area to high intensity management leaves a large area under private management to relatively low management intensities. Alternative scenarios will be implemented to identify the allocation of management intensities by private timberland owners when, for example, investment in high levels of management is restricted.
Baisden, W. Troy (Landcare
Research, New Zealand Ltd, Private Bag 11052, Massey Univ Campus,
Palmerston, North5300, New Zealand,
Phone: +64 6-356 7145; Fax: +64 6-355-9230; Email:
baisdent@landcareresearch.co.nz)
Making Carbon-Trading Mechanisms Accessible to Indigenous
Groups: Lessons From Working with Maori in
G. Harmsworth, W.T. Baisden*
Many researchers and policy makers acknowledge that land owned and managed by indigenous groups differs from land owned and managed under more Western ownership and governance-type models. Differences may include characteristics such as landownership and management structures, historical connection, and land quality, as well as legislation, and policies and practice that guide land use and management. Designing policy instruments to permit C trading within a nation therefore needs to recognise these differences where indigenous populations exist and to design policies that are cognisant of differing land-governance frameworks, economic status, and socio-cultural aspirations. We describe research we are conducting with a range of stakeholders – mostly landowners and policy agencies – to identify opportunities for indigenous Maori to contribute through forest carbon sinks to help New Zealand meet its commitments under the newly signed Kyoto protocol. We have focused our work to date on the North Island East Coast Region of New Zealand, an area with extensive undeveloped and erosion-prone Maori land. In this research we have defined the areas of Maori owned land under different forms of land use, vegetative cover, and land capability or type. We are in the process of determining the economic and policy considerations required to increase Maori participation in New Zealand’s afforestation-based climate change mitigation policy. Perhaps surprisingly, our 2 key findings describe: 1) the need to understand complex governance structures for Maori land, often involving tens to hundreds of owners – many of whom are absent from participatory decision-making, and 2) the need to determine Maori community aspirations for land. We find that appropriate land-covenanting policies can be modeled on existing policies to maintain and enhance biodiversity, but that all policies must consider governance. There is a need to develop appropriate models and contracts for income generation for distinct land areas through time, often dealing with successive ownership generations (at least 50 years), and identifying successive sources of income. Additionally, we have identified that the most important contribution on Maori land for climate change mitigation may be to develop initiatives that reduce indigenous scrub clearance, such as for plantation forestry and pasture, rather than just encourage the regeneration of native forests as we had originally assumed. These findings emphasize the importance of developing an integrated socio-economic understanding of Maori land that identifies community, district, and regional aspirations to achieve long-term success, realise potential opportunities, and effect change. We present our research as a model for effectively working with indigenous groups in the development of carbon trading, either within developed nations or in CDM projects.
Baisden, W. Troy (Landcare Research, New Zealand Ltd, Private Bag 11052, Massey Univ Campus, Palmerston, North5300, New Zealand; Phone: +64 6-356 7145; Fax: +64 6-355-9230; Email: baisdent@landcareresearch.co.nz)
High Riverine Transport of Particulate Organic Carbon in New Zealand: Potential Significance of Soil Erosion to Carbon Accounting
D.T. Scott, W.T. Baisden*, N.J. Preston, N.A. Trustrum, R. Davies-Colley, R.A. Woods, D.M. Hicks, B. Gomez, M.J. Page, K.R. Tate
Tectonically active small island nations contribute a disproportionate amount of sediment to the world’s oceans-. For such nations, particulate organic carbon (POC) export associated with riverine sediment load can also be important compared with C fluxes reported under the United Nations Framework Convention on Climate Change (UNFCCC) and accounted for under the Kyoto Protocol. We quantified the total riverine export of particulate organic carbon (POC) from New Zealand’s landscape to the ocean. New Zealand comprises 0.1% of global land area, 0.2% of the world’s CO2 emissions, and 1% of global riverine sediment flux. POC export was estimated at 3±1 Mt C yr-1 (10±3 tC km-2yr-1). The total POC yield represents a movement of C equivalent to approximately one third of New Zealand’s total fossil fuel emissions, although this erosional flux cannot be treated as an emission to the atmosphere since a large proportion of POC may be sequestered in ocean sediments. Since elevated rates of erosion are associated with non-forested landcover, reforestation may contribute to changes in riverine POC fluxes. However, our calculations suggest that only 1.7% of New Zealand’s land area yields sufficient human-induced POC to rivers to be of concern in C accounting. Our approach of identifying ‘hot spots’ of erosion where significant uncertainties may interfere with C accounting potentially allows C accounting and trading to proceed based on existing rules in the vast majority of the landscape.
Baisden, W. Troy (Landcare Research, New Zealand Ltd, Private Bag 11052, Massey Univ Campus, Palmerston North, 5300, New Zealand; Phone: +64 6-356 7145; Fax: +64 6-355-9230; Email: baisdent@landcareresearch.co.nz)
Significant Bomb C-14 Responses in Soils Below 30 cm Depth: A Previously Unrecognized Decadal C Pool?
W.T. Baisden*
Globally, soil organic matter contains approximately 1500 Pg C to 1 m soil depth and 2300 Pg C to 3 m depth—more than biomass and atmospheric CO2 combined. Efforts to account for the effects of land-use or vegetation change on soil organic carbon (SOC) stocks normally limit their focus to the upper 20–30 cm of the soil profile, yet 0–20 cm SOC stocks are only 42% of 0-1 m SOC. Accounting for only the upper 20–30 cm of SOC has been justifiable based on the assumption that deeper SOC is unreactive since it displays 14C-derived mean residence times of hundreds or thousands of years. Recent findings indicate that, at depths of 40–100 cm, a well-studied New Zealand silt-loam soil displays progressive Delta 14C enrichment of over 200 per mil across samplings in 1959, 1974 and 2002, indicating incorporation of bomb 14C during the last 40 years. This pattern of deep 14C enrichment – previously observed in two well-drained California grassland soils – suggests that roots and/or dissolved organic C (DOC) transport contribute to a Decadally-Reactive Deep Soil C (DRDSC) pool. Soil sampled in 1970 and 2002 from a chronosequence of New Zealand sand dunes deposited from ~100 to 15,000 years ago confirms this pattern of deep soil response to the bomb14C spike. However, in these better drained profiles in more humid climates, the bomb- 14C pulse has passed at depths of 55–80 cm, evidenced by a Delta 14C decline of ~70 per mil. This SOC pool can react to land-use or vegetation change.
Bangsund, Dean (North Dakota State University, P.O. Box 5636, Fargo, ND, 58105; Phone: 701-231-7471; Fax: 701-231-7400; Email: bangsund@ndsuext.nodak.edu)
Carbon Sequestration in Spring Wheat Producing Regions of
the
D.A.
Bangsund*, F.L. Leistritz
Carbon sequestration in crop land is currently viewed as a low-cost option to mitigate the increase in greenhouse gas emissions. Existing research suggests that at low carbon prices the primary carbon sequestration activities would be changes in tillage practices and as carbon prices increase some changes in land use are likely to occur in various regions of the United States. This study evaluated land management and land use alternatives that are likely to occur with carbon incentives in the northern Great Plains. Historically, the region has relied heavily on the use of summer fallow; however, producers are finding economic advantages in adopting conservation and no-till systems in continuous cropping practices in the absence of external incentives. Further, producers in the region have consistently demonstrated a willingness to enroll crop land in long-term conservation programs. The conversion of crop land to perennial grasses is an alternative land use that has high carbon sequestration potential in the northern Great Plains. Producers within the region were differentiated by three levels of profitability and by three types of tillage practices. The highest expected net present value of a future stream of carbon payments and net returns associated with tillage and land use alternatives was determined for each combination of profitability and tillage practice. Results suggest that by including modest revenues from co-products, perennial grass is not only an economically viable alternative to crop production in the region, but may be economically viable at carbon prices lower than have been previously suggested. In addition, just as soil type, crop rotations, and tillage practices have been used to differentiate carbon sequestration potential within a given area, this study indicates that profitability measures also should be used to further differentiate the response of producers to carbon incentives.
Bernacchi, Carl (Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL, 61820; Phone: 217-333-8048; Fax: 217-244-0220; Email: bernacch@uiuc.edu)
Carbon Budget of Mature No-till Ecosystem in North Central
Region of the
C. J. Bernacchi*, S.G. Hollinger, T. Meyers
Continuous measurements of carbon flux data from 1997 through 2002 were used to evaluate the carbon budget for a no-till maize (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation agricultural ecosystem using the eddy covariance technique. These measurements were used to determine the Net Ecosystem Exchange of carbon (NEE) at the local and regional scales. Results show that on the local and regional scales, the maize/soybean no-till ecosystem is a carbon sink; however, corn is the dominant sink in the ecosystem. Locally, the sink is mostly explained by the carbon stored in the grain, which is removed from the field during harvest. On a regional scale, the sink is proportionally lower than that of the local scale, which is attributed to regional consumption of the grain. Nearly 100% of both maize and soybean yields are consumed annually, e.g., all carbon stored in grain is consumed somewhere in the world. The grain consumption results in a much lower carbon sink, but the results imply that long-term carbon-sequestration potential of this no-till ecosystem exists.
Birdsey, Richard (USDA-Forest
Service, 11 Campus Blvd, Suite 200, Newtown Square, PA, 19073; Phone:
610-557-4091; Email: rbirdsey@fs.fed.us)
Carbon Accounting Rules and Guidelines for the United States Forest Sector
R. Birdsey*
The President’s Climate Change Initiative includes improvements to the Department of Energy’s Voluntary Greenhouse Gas Reporting Program. As part of the initiative, the USDA Forest Service is developing accounting rules and guidelines for reporting and registering forestry activities that reduce atmospheric CO2 by increasing carbon sequestration or reducing emissions. To be eligible for registration, the reported reductions must use methods and meet standards contained in the guidelines. Forestry presents some unique challenges and opportunities because of the diversity of operations (e.g. size and location of operations), the variety of practices that affect greenhouse gases, the year-to-year variability in emissions and sequestration associated with forest activities, and some special considerations such as accounting for the effects of natural disturbance. Forestry activities with potential for achieving substantial reductions include, but are not limited to: afforestation, mine land reclamation, and forest restoration; agroforestry; forest management; short-rotation biomass energy plantations; forest preservation; wood products; and urban forestry.
Bohm, Sven (Michigan State
University, 3700 Gull Lake Dr, Hickory Corners, MI, 49060; Phone: 51-3550223;
Email: bs@rootimage.msu.edu)
S. Bohm*, G.P. Robertson
We are using automated static chambers for frequent measurements of N2O emissions from soils under four different agricultural management systems (conventional, no-till, and organic soybean-wheat-corn rotations and continuous alfalfa). N2O emissions are sampled four times per day, and simultaneous measurements of soil moisture and temperature provide ancillary emission data, as do periodic soil nitrate measurements. Fluxes vary smoothly over the time period thus far measured, suggesting that we are capturing most of the temporal variability present in the systems. N2O emissions often vary more than three-fold over a single day. Longer term trends appear related to soil moisture, temperature, and nitrogen availability. Maximum fluxes were nearly ten times higher in the conventional treatment than in the other treatments. Data will be used to test current models of N2O emission, including DAYCENT.
Bolstad,
P. V. (University of Minnesota Dept. of Forest Resources, 115 Green Hall, St.
Paul, MN, 55108; Phone: 612 624-9711; Fax: 612 625-5212; Email:
pbolstad@umn.edu)
Simulating Carbon Dynamics
in Forests - What May We Learn From Agriculturalists?
P.V. Bolstad*
More studies have focused
on agricultural management and soil carbon (C) than on forests, forest
management, and soil C storage. This is in part due to the relatively broader
and deeper understanding of management impacts on agricultural soils, the range
of management options possible in agroecosystems, and the history, number, and
breadth of long-term soil C studies in agricultural settings.
There are a large and growing number of soil carbon models, and these models
differ in their objectives, structure, and outputs. Many models focus on
intensively managed, annual agricultural systems; a smaller set have focused on
extensively managed or unmanaged systems, predominantly forests or grasslands,
and a smaller set have been developed and tested across both forest and
agricultural ecosystems at a range of management regimes. This talk describes
and contrasts the basic approaches used in soil C models for agricultural and
forested systems, evaluates the ability to integrate
changes in forest management regimes on predictions in forest soil and
ecosystem C storage, and identifies steps necessary to integrate management
sensitivity and improve the quality of forest soil C models.
Borgo, Marília (SPVS, Rua
Gutemberg, 296, Batel, 80420-030, Curitiba, Pa; Curitiba, PR, 80420-030,
Brazil; Phone: 0412420280; Fax: 0412420280; Email: maborgo@spvs.org.br)
M. Borgo*, G. Tiepolo, D.N. Cardoso, I.A. Andrade
The Atlantic Rainforest Restoration Project (ARRP – Cachoeira
Natural Reserve) implemented by Wildlife Research and Environmental Education
Society (SPVS) in a partnership with The Nature Conservancy and General Motors
has a current area of 8,600.0 ha and it is located at Paraná state, Brazil,
within Environmental Protection Area of Guaraqueçaba. A vegetation map for the
ARRP area was done and several types of forests and their sucessional stages
and other land uses were identified and classified. Vegetation stratified
sampling was done using forest coverage (Submontane Forest, Wetland forest,
Advanced/medium, Medium and Young Secondary Forest, according to the period
that the original forest coverage had been disturbed). Another sampling based
on soil and vegetation maps was conducted in the same plots used in the simple
stratification. In addition to those forest strata, other non-forest classes
such as pasture, herbaceous and shrubs vegetation were also included as part of
the carbon inventory, but temporary plots were used for those strata. The
methodology chosen for the carbon inventory was the one developed by Winrock
International and adapted to the project conditions. For the vegetation classes
of pasture/shrub and open areas destructive sampling was carried out in 24
plots. The total aboveground biomass for non-forest strata in ARRP was 3732 t
C. The total carbon in the forest strata (excluding soil) was 764.847 t C. The
overall weighted mean of total carbon content of forests is 88 t C ha-1, 77 %
of which in the aboveground biomass. Total dead wood carbon represents about
6.1% of the aboveground carbon biomass. Small trees (dbh greater than 5 cm)
represented 1.5% of total biomass and roots were 20% of the aboveground
biomass, and represents 15% of the total amount. Considering just aboveground
biomass, there is a total pool of 577,555 t C. Coefficients of variation for
aboveground total carbon content by strata were relatively low except by the
lowland forest. The coefficients range from 24-33% (lowland – 91%). Seventeen
forest strata were distinguished by combining soil classes and vegetation
types. Compared to the simple stratification, the total number of plots is
16.5% lower. The soil-vegetation stratification is better because it combines
specific environmental conditions of forest and soil classes and it reduces the
variation within each vegetation class. The total carbon in the forest strata
using the stratification based on vegetation and soil maps (excluding soil) was
764,812 t C. Total aboveground biomass was 589,326 and mean carbon stocks for
aboveground biomass ranged from 42-135 t C ha-1. Comparing
aboveground biomass between soil and soil-vegetation stratification, the best
sample was at the second method, with increases around 2% (or 11,700 t C) in the
total aboveground in the inventory. As a result of the carbon inventory
conducted in the ARRP it was possible to quantify the amount of carbon stored
with a good level of precision (p=0.05). The inventory was used to estimate the
differences between the with- and without-project carbon pools and is the
primary basis for determination of project GHG benefits. The results of this
effort will help to improve and develop models to measure and monitor carbon
stock in heterogeneous landscapes, such as the ones found in the Atlantic
Rainforest. This project was developed with the funds from Initiative for
Climate Action Project Research of Department of Energy (DOE) and National
Energy Technology Laboratory of USA (DE-FC26-01NT41151).
Bostick, W. McNair (University of Florida, Dept. of Ag. and Bio. Engineering, 1 Frazier Rogers, Gainesville, FL, 32611-0570; Phone: 352-392-1864 x 292; Fax: 352-392-4092; Email: mcnair2@ufl.edu)
Stochastic Simulation and Data Assimilation for Estimation of Soil Carbon Dynamics
W. M. Bostick*, J. Koo, J. W. Jones, G. Hoogenboom, V. Bado, W. D. Graham
The large land areas needed to sequester tradable amounts of carbon (C) will lead to uncertainty in estimates of soil C dynamics in sequestration projects. The objective of this paper is to present a method that uses the Extended Kalman Filter (ExKF) algorithm for assimilating simulations and measurements to reduce uncertainty in estimates. The method uses a stochastic soil C model to propagate model states, their variance and the covariance between states at different locations. When measurements are made, the ExKF updates model states at locations that are measured and unmeasured. The degree to which simulated states are updated depends the difference between simulations and measurements and on the magnitudes of the measurement variances, the simulated variances and simulated covariances of model states. In general, low measurement variance, relative to the simulation variance, can yield large state updates when measurements are assimilated. On the other hand, if simulation variance is low, relative to the measurement variance, measurements may have little effect on state estimates. Larger covariances between states at measured and unmeasured sites may yield larger updates at the unmeasured site. We demonstrate the use of this method with a long-term rotation experiment from Burkina Faso. Soil C samples from the experiment were used to initialize the initial C states. A semi-variogram model was also developed from these data and used with multi-Gaussian stochastic simulation to initialize the covariance matrix. The ExKF performance was analyzed for different measurement strategies. For all measurement scenarios considered, aggregate C estimates were more accurate than measurement or simulation results alone. In addition, the variance of the aggregate filtered estimates decreased as data were assimilated. In contrast, the variance of simulation estimates alone increased over the period of estimation.
Brenner, John (USDA-Natural Resources Conservation Service, U.S. Bancorp Tower, 111 SW 5th Avenue, Suite 1200, Portland, Oregon, 97204; Phone: 503-273-2409; Fax: 503-273-2401; Email: john.brenner@por.usda.gov)
Estimating Soil C Changes for the US 1605B Program ‘Voluntary Reporting of Greenhouse Gas Mitigation’
John Brenner*, K. Paustian, M. Easter, K. Killian, J. Schuler, S. Williams
A system for voluntary reporting of greenhouse gas emission reductions was established as part of the US policy for addressing global climate change issues. The system is administered by the USDOE and has recently been revised and improved as part of the Administration’s Climate Change Initiative. Emission reductions through agricultural activities, including soil C sequestration and reductions in on-farm fuel usage are included in the reporting system. Here we describe the design, data sources and reporting capabilities of an on-line, web-based estimation tool that is included as part of the 1605B system.
Brewer, Elizabeth (Bradley
University, 1501 W. Bradley Ave., Biology Department, Peoria, IL, 61625; Phone:
309-677-3809; Fax: 309-677-3558; Email: ebrewer@bradley.edu)
E.A. Brewer*, S.J. Morris, E.A. Paul, G.P. Robertson
A variety of land-use change strategies targeted towards increasing carbon (C) storage in terrestrial systems have focused on converting some agricultural fields to forest. Research to date suggests some strategies are more successful than others at improving belowground C stocks. Our research evaluates the potential use of calcium (Ca) and nitrogen (N) for improving soil C stabilization when agricultural lands are returned to forest. Past work suggests that sandy or acidic soils of the eastern U.S. do not sequester C under pine unless adequate Ca is present. To evaluate the degree to which Ca and/or N additions can increase C sequestration, field plots were established in an afforested red pine stand with low soil C content. Treatments included control (no amendment), addition of CaCl2, addition of NH4NO3, and additions of CaCl2 and NH4NO3. Lime was not used in this study so that contributions of lime-CO2 to atmospheric pools would not be a confounding factor in evaluating C sequestration. Each treatment was also incorporated with litter, to a depth of 20 cm. Biological fractionation incubations were established on soils collected one year after amendment, to evaluate changes in C and N pools. Incubations were also established using soil retrieved from our field site but amended in the laboratory. Amendments included all treatments used in the field but also examined Ca added as lime (CaCO3) amendments to evaluate the differential impacts of Ca source. Overall, our results suggest that impacts of Ca addition on C accrual are dependent of the form of Ca added and method of application, surface versus incorporation. Analysis for main effects and interactions suggest increases in total and resistant C pool sizes with addition of CaCl2 and litter incorporation but there were no differences in mean residence times (MRT). Field respiration measurements showed decreased respiration from CaCl2 amended plots suggesting sequestration. Impacts of N were dependent on whether N was added alone, or in the presence of Ca. Plots with N additions alone showed an increase in total C, compared to plots where N was added with Ca. Field respiration also showed the interaction with increased respiration when N was added with Ca. Nitrogen additions had little impact on N cycling parameters measured either initially or 1 year after amendment, however, CaCl2 decreased N mineralization rates further supporting sequestration. The study supports the hypothesis that Ca and N amendments will increase soil C sequestration. These treatments could easily be incorporated into management schemes and result in increases in soil C in managed systems. Longer-term measurements on these sites are necessary to extrapolate the data collected here to a viable management strategy.
Brown, Sandra (Winrock International, 621 N Kent St., Suite 1200, Arlington, VA, 22209; Phone: 703-525-9430 x 678; Email: sbrown@winrock.org)
Estimating the Potential Carbon Supply from Changes in Land Use: Afforestation of Grazing Lands in the USA as a Case Study
S.Brown*, A.Dushku, J.Kadyszewski
Most estimates of carbon sequestration potential on the land tend to be of the theoretical potential, without consideration of current land values and alternate uses. To fill this gap in knowledge, the goal of this work is to answer the basic question: “How many carbon credits would landowners offer for sale for a particular class of activity at various price points and where are these located?” Information about current land use, potential changes in land use and the incremental carbon resulting from the change, opportunity costs, conversion costs, annual maintenance costs, and measurement and monitoring costs were obtained and used in the analyses for two regions in the USA (west coast and south central states). The analyses are performed in a geographic information system (GIS) to include the diversity of land uses, rates of carbon sequestration, and costs over three time periods of 20 years, 40 years and 80 years. We will present the general approach that was used to identify and locate classes of land where there is potential to change the use to a higher carbon content, estimate rates of carbon accumulation for each major potential land-use change activity for each land class, and assign values to each contributing cost factor. Results indicate that at a price of less than $10/t C, about 230 million tons of carbon could be sequestered over 40 years by afforestation of 1.1 million hectares of existing grazing lands in Arkansas, Louisiana, and Mississippi. If the price of carbon was up to $20/ton, twice as much carbon could be sequestered on about 4 million ha in these southern states. In the western states (e.g. CA and OR), similar amounts of carbon could be sequestered by afforestation after 40 years for the same price points, but more land would be needed.
Burton, D. (Nova Scotia
Agricultural College, 20 Tower Road, Truro, NS, B2N 5E3, Canada; Phone:
902-893-6250; Fax: 902-893-0335; Email: dburton@nsac.ns.ca)
Utilization of Animal Manure in Potato Production: Reducing Greenhouse Gas Emissions Through Improved Nitrogen Management
D. Burton*, J.A. MacLeod, B. Thangaraj, B.J. Zebarth
The study, conducted at the Crops and Livestock Research Station, Charlottetown, examines greenhouse gas emissions from a potato-barley-sweet clover rotation. The objectives of the project were to: i) collect baseline information from the standard three-year potato rotation in Prince Edward Island; ii) determine the effect of different manure management strategies within the potato rotation on nitrous oxide emissions; and iii) identify the potential to reduce nitrous oxide emissions through improved nitrogen management practices. The experiment had four N fertility treatments, replicated three times. The treatments are: i) mineral fertilizer (NH4NO3) applied in the spring of the potato year of the rotation; ii) solid swine manure applied in the fall before the potato year; iii) solid swine manure applied in the spring of the potato year; and iv) liquid swine manure applied in the spring of the potato year. Spring and early summer periods (mid-May to end of June) were the times of greatest N2O emission. The potato year of the rotation resulted in the greatest N2O emissions. In the potato year solid manure resulted in less N2O emission than did liquid manure or NH4NO3. Differences in N2O emissions between years and treatments corresponded with treatment effects on soil NO3- concentration. Nitrate and N2O emissions in tile drainage water was monitored as part of parallel studies.
Camps Arbestain, Marta
(NEIKERNEIKER, Berreaga, 1DERIO-BIZKAIA, 48160, Spain; Phone: 34944034328; Fax:
34944034310; Email: mcamps@neiker.net)
Determination of Organic Carbon Fractions of Agricultural and Forest Soils on the Basis of Their Degree of Oxidation with Permanganate
M. Camps Arbestain*, Z. Madinabeitia, I. Martinez de Arano, A.Gonzalez
Arias, M. Pinto, A. Aizpurua, M.A. Ortuzar, F. Macias
The aim of the present study is to investigate the lability of soil organic carbon (SOC), measured on the basis of the ease of its oxidation with permanganate. For this, samples of the surface horizons of 44 soils under Fagus sylvatica L., 35 soils under Pinus radiata D. Don, 20 soils under Quercus ilex L., and 12 agricultural soils, all located in the Basque Country (N Spain), were analyzed. Most of the soils under Fagus sylvatica stands have developed from marlstones, sandstones, and limestones, and those under Pinus radiata stands from marlstones, sandstones and volcanic materials. On the other hand, most agricultural soils and those under Quercus ilex stands have developed from limestones. The soils were air-dried and passed through a 2-mm sieve prior to analysis. The oxidability of SOC by permanganate in the Fagus sylvatica forest soils was determined with 33 mM KMnO4 after different incubation times (1 h, 3 h, 6 h and 24 h), and that of the rest of the soils with the same reagent after 1 h incubation. For all soils, general soil properties (SOC, total N, pH, CEC, particle-size distribution) were determined. Analysis of SOC was carried out with (i) K2Cr2O7, following the Walkey-Black method, and (ii) a LECO C analyzer (corrected for carbonates when present). The Fourier transform infrared spectra of untreated soil samples were also obtained. The pH values of soils under Fagus sylvatica stands ranged between 4.0 and 8.2, those of under Pinus radiata stands between 4.0 and 7.5, and those under Quercus ilex stands between 4.3 and 8.5, whereas the pH range of the agricultural soils studied was narrower (7.6-8.4). The organic C data corresponding to the soil samples is currently being analyzed.
Capalbo, Susan (Montana State
University, Dept. of Agricultural Economics and Economics, Bozeman, MT,
59717-2920; Phone: 406-994-5619; Fax: 406-994-4838; Email: scapalbo@montana.edu)
Estimating the Economic Potential for Agricultural Soil Carbon Sequestration in the Central U.S. Using an Aggregate Econometric-Process Simulation Model
J. Antle, S. Capalbo*, K. Paustian
As the scientific evidence
supporting the hypothesis of anthropogenic global warming and climate change
has grown, so has the demand for viable greenhouse gas (GHG) mitigation
strategies. Research has shown that agricultural GHG mitigation could offset a
relatively small proportion of total U.S. emissions and that agricultural soil
carbon sequestration could be cost effective. Studies of economic potential for
soil carbon sequestration conducted to date have been based on either
field-scale economic simulation models covering relatively small regions where
such data are available (e.g., cites) or on sectoral models. However,
site-specific field-scale or farm-scale data are not generally available for
large regions of the U.S. and other countries; nor are the data and parameters
available to implement sectoral models for many regions of the world.
Consequently, analysis of economic potential for agricultural soil carbon
sequestration has been limited to selected regions within the U.S. and for
selected sectors. The purpose of this paper is to develop and apply a method to
assess economic potential for agricultural GHG mitigation that can be
implemented using existing secondary data, such as the agricultural census data
available in the U.S. and many other regions of the world, combined with
widely-available estimates of soil carbon stocks derived from biophysical
simulation models such as Century (cites) or from simpler estimation methods.
This economic methodology utilizes the principle of opportunity cost on which
detailed micro-economic analysis of agricultural GHG mitigation potential is
also based. However, in place of simulation models based on site-specific
field-level or farm-level data, the method proposed here is based on the
estimation of conventional econometric profit function models with agricultural
census data aggregated to the county scale for a region such as the central
U.S. We also use this model to investigate the importance of two issues that
have been identified as potentially critical in the assessment of carbon
sequestration potential, namely the impact of spatial scale at which carbon
stocks and changes are estimated, and the effects of transaction costs on
economic feasibility of soil carbon sequestration contracts. Simulations for
the central U.S. show that reduction in fallow and conservation tillage
adoption in the wheat system could generate up to about 1.7 million MgC/yr,
whereas increased adoption of conservation tillage in the corn-soy-feed system
could generate up to about 6.2 million MgC/yr at a price of $200/MgC. Due to
the relatively high price elasticity of response, at least half of this
potential could be achieved at relatively low carbon prices (less than $100 per
ton). The aggregate econometric-process model used in this analysis was found
to produce estimates of economic potential for soil carbon sequestration
potential similar to results produced by much more data-intensive, field-scale
models. This result suggests that this simpler, aggregate modeling approach can
produce credible estimates of soil carbon sequestration potential.
Carlisle, Eli (Univeristy of
California-Davis, Dept. of Viticulture, Davis, CA, 95616; Phone: 530-754-7144;
Email: ecarlisle@ucdavis.edu)
Conversion of Oak Woodlands to Vineyards Alters Physical Constraints on Soil CO2 Respiration in a Mediterranean Climate Ecosystem
E.A. Carlisle*, K.L. Steenwerth, D.R. Smart
We examined constraints on annual soil CO2 respiration at unmanaged oak woodlands and adjacent vineyards that were converted from oak woodlands approximately 30 years ago in the Oakville Region of Napa Valley, California. All sites were located on the same soil type, a Bale (variant) gravelly loam (Fine-loamy, mixed, superactive, thermic Cumulic Ultic Haploxeroll) and dominated by C3 vegetation. Seasonal soil CO2 efflux was greatest at the oak woodland sites, although during the dry summer periods the rates measured from oak sites were at times similar to those measured from vineyards. In spite of the fact that CO2 efflux rates were higher, soil profile CO2 concentrations were lower at the oak-woodland sites, except at the shallowest depth (15 cm). Soil gas diffusion coefficients for the oak sites were larger than for the vineyard sites. Long-term annual cultivation of the vineyard soils apparently increased bulk density, diminished porosity, and thus altered the effective gas diffusivities. In addition to lower CO2 production, lower diffusion coefficients may help account for the lower rates of CO2 efflux and higher CO2 concentrations in vineyard soil profiles. Vineyard soil CO2 was more depleted in 13C throughout the soil profile below 30 cm as indicated by more negative d13C ratios, and points to different respiratory C sources in vineyard soils. Annual C losses were less from the vineyard soils (7.02 ± 0.58 Mg C ha-1 yr-1) as compared to the oak soils (15.67 ± 1.44 Mg C ha-1 yr-1), and both were comparable to losses reported in previous investigations.
Chang, Chi (AAFC, Lethbridge, AlbertaLethbridge Research Centre, Agriculture and Agri-Food, Lethbridge, AB, T1J 4B1, Canada; Phone: 403 317-2220; Fax: 403 317-2187; Email: chang@agr.gc.ca)
C. Chang*, X. Hao, G. Clayton
Animal manure application to land has been shown to increase soil organic carbon content and changes in soil physical, chemical, and biological properties. Land application of animal manure, either in raw or composted form, is also considered part of strategies for C-sequestration. However, the rates of change in soil organic C content (concentration) and the rates of increase in the total amount of soil organic C accumulation in the soil profile in relation to the total cumulative amount of organic C applied through feedlot cattle manure application are not well known. A long-term cattle feedlot manure land application field study was initiated in the fall, 1973 in Lethbridge Alberta, Canada. The annual manure application rates were 0, 30, 60 and 90 Mg ha-1 for nonirrigated and 0, 60, 120 and 180 Mg ha-1 (wet weight) for irrigated land. The results showed that soil organic C content (concentration) in the surface 15 cm of soil increased curve linearly with cumulative amount of organic-C applied through manuring under both non-irrigated and irrigated conditions. The total amount of soil organic C increase in the soil profile from 0 to 60 cm depth interval also increased with cumulative organic C applied. The rate of increase in surface soil organic C content and total amount of soil organic C in the profile can be calculated. This information is useful in evaluating C sequestration through long-term manure application.
Chen, Hua (School of Forestry and
Wildlife Sciences, Auburn University, Auburn, AL 36849, Phone: 334-844-1057; Fax: 334-844-1084; Email:
chenj@geog.utoronto.ca)
Effects of Cropland Abandonment and Forest Regrowth on
Terrestrial Carbon Storage in
Hua Chen*, Hanqin
Tian, Chi Zhang, Mingliang
Liu, Shufen Pan
Southeast is thought to be the largest carbon sink across the six major bioclimatic regions of the conterminous United States. Cropland abandonment and forest regrowth are two potentially important factors to be responsible for this carbon sink. The objective of this study is to examine how land uses change, especially cropland abandonment and forest regrowth, on terrestrial carbon storage in southeastern US. We have compiled and developed the historical annual cropland gridded data set of southeastern US between 1850 and 2000 with a spatial resolution of 4 km. This data set has been used as input of the Terrestrial Ecosystem Model (TEM) to simulate land use effects on carbon fluxes and storage in the region. According to the preliminary analysis, our results indicate that, from 1850 to 2000, cropland area decreased more than 50%, most of which was converted to forests. Our preliminary analysis indicates that forest regrowth after cropland abandonment has resulted in a carbon uptake in the southeast, and the magnitude of the carbon sink varies over space and time.
Chen, Jing M. (Department of Geography, University of Toronto, 100 St. George St., Toronto, Ontario, Canada, M5S 3G3; Phone: 416-978-7085; Fax: 416-946-3886; Email: chenj@geog.utoronto.ca)
Mapping Carbon Source
and Sink Distributions in Canada’s Forests and Wetlands Resulting from Disturbance
and Non-disturbance Effects
Jing M. Chen*,
Weimin Ju,
In collaboration with several federal government agencies and universities, annual spatial distributions of carbon sources and sinks in Canada’s forests and wetlands at 1 km resolution are computed for the period from 1901 to 1998 using ecosystem models that utilize remote sensing images and gridded climate, soils, and forest inventory data. GIS-based large fire polygons for most regions of Canada are used to develop a remote sensing algorithm for mapping and dating forest burned areas in the 25 years prior to 1998. These mapped and dated burned areas are used in combination with inventory data to produce a complete image of forest stand age in 1998. Empirical NPP-age relationships were used to simulate the annual variations of forest growth and carbon balance in 1 km pixels, each treated as a homogeneous forest stand. Annual CO2 flux data from five sites were used for model validation. The Integrated Terrestrial Ecosystem Carbon Cycle Model (InTEC) was developed (Chen et al., 2000) for this carbon source and sink mapping in annual time steps. This model is supplemented by a daily model named Boreal Ecosystem Productivity Simulator (BEPS) for detailed simulations in recent years (Liu et al., 2003). InTEC is recently expanded to include aerobic and anaerobic processes in wetlands, so that the total carbon absorption and release by CO2 and CH4 gases are also included. Both disturbance (fire, insect, harvest) and non-disturbance (climate, N, CO2) factors and their interactions are included the model. The significance of these new national statistics of the carbon budgets of Canada’s forests and wetlands will be discussed in comparison with previous results.
Cherney, Jerry (Cornell University, Dept. of Crop and Soil Sciences, 503 Bradfield Hall, Ithaca, NY, 14853; Phone: 607-255-0945; Fax: 607-255-2644; Email: jhc5@cornell.edu)
J.H. Cherney*, P.B. Woodbury, S.D. DeGloria
Use of herbaceous biomass for energy production can
significantly reduce greenhouse gas emissions in the northeastern USA. Our
objective was to evaluate the potential for grass production in New York State
and to develop agronomic management strategies to improve the energy
characteristics of this feedstock. The northeastern USA has a considerable
acreage of unused or underutilized agricultural land. The estimated potential
underutilized crop area in New York State is approximately 1.5 million acres,
based on data from satellite imagery and the census of agriculture. Some of
this land is reverting back to woody growth while some of it is in government
programs. Much of this land has encountered difficulties growing row crops and
is in some type of grassland. Almost all of this land could grow grass crops
for bioenergy, regardless of how marginal the soils are for agricultural
production. Potential yield estimates of 1.25 ton/acre unimproved grassland,
and 2.5 ton/acre for managed switchgrass (Panicum
virgatum L.) and reed canarygrass (Phalaris
arundinacea L.) were selected as economic cutoff values for production of
these crops. Based on these economic cutoffs reed canarygrass could be
established on 96% of currently unused acreage, while switchgrass could be economically
established on 80% of this acreage. Without any fertilization or other inputs
approximately 81% of this unused land could be economically harvested once a
year for biomass. Based on soil-specific predicted crop yields approximately 6
million tons of reed canarygrass could be produced on these lands in New York
State. Ash content of grasses has a major impact on combustion value of the
feedstock. Six fields of mixed cool-season grasses with some legumes and weeds
were cut in August 2004 and harvested two to three weeks after cutting using
commercial hay equipment to evaluate ash reduction strategies. Primary species
were timothy (Phleum pratense L.),
tall fescue (Festuca arundinacea
Schreb.), alfalfa (Medicago sativa
L.), tall oatgrass (Arrhenatherum elatius
L.), goldenrod (Solidago canadensis
L.) and bedstraw (Galium aparine L.).
The range in ash content of these primarily grass mixtures was 3.9-5.2%. Energy
value of grass ranged from 19.6-21.2 MJ/kg, compared to 21.7 MJ/kg for premium
wood pellets. All grass samples contained 0.01% sodium, while potassium content
ranged from 0.43-0.82%. Sulfur ranged from 0.09-0.12% and chloride ranged from
0.01 to 0.04%. This compares to premium wood pellets with ash = 1%, sodium =
0.02%, potassium = 0.10%, and no detectable sulfur or chloride. Grass pellets
are currently being tested in pellet stoves, pellet boilers and gasifiers in
Europe and North America. Grass biofuel pellets emit up to 90% less greenhouse
gasses than conventional energy sources such as oil, coal and natural gas. If
approximately 5.5% of all residential buildings in New York State were heated
with pelleted grass or wood, this could offset 100% of all greenhouse gas
emissions attributed to agriculture in New York State. Perennial grass is ideal
for animal manure nutrient management, soil conservation, maintaining open
spaces, and compatible with wildlife nesting opportunities. A simple one cut
per season perennial grass biomass program has maximum sustainability for an
agricultural cropping system. Grass pellet biofuel is a very promising
sustainable, economically-viable, and environmentally-friendly alternative
energy source. It has great potential for near-term implementation and positive
impact on greenhouse gas emissions.
Choi, Suk-won (The Ohio State University, AED Economics, 2120 Fyffe Rd., Columbus, OH, 43210; Phone: 614-292-9424; Email: choi.151@osu.edu)
Economic Analysis of Soil Carbon Sequestration: Dynamic Model on Corn and Soybean in the Midwest US
S.Choi*, B.Sohngen
This study investigates the
cost and potential of carbon sequestration in agricultural soils in three
Midwestern states (Ohio-Indiana-Illinois).
Previous economic studies have ignored several important features of
soil carbon sequestration policy, such as the broad range of residue management
intensity level observed in practice, the potential for emissions when the land
is tilled, the cyclical patterns of crop rotations, and the spatial pattern of
soil carbon. To investigate the influences of these factors, this study
develops a dynamic model that maximizes the net present value of market welfare
on corn and soybean, and chooses optimal solutions for residue management
intensity, crop choices between corn and soybean. The model is implemented in
48 soil regions of a 3-state region -- Ohio, Indiana, and Illinois. Two different carbon policies are examined: a
program that rents new and additional carbon, and a program that offers a fixed
payment to maintain land in permanent conservation tillage or no-tillage. For the fixed payment scenario, we examine
two additional alternatives: one that requires only 35% residue to enter the
program (i.e. conservation tillage), and one that requires more than 75%
residue to enter the program (i.e. no-tillage). The results suggest that under
the carbon renting program it is possible to sequester 5-50 million tC (1 tC =
1000 kg C), or 0.1 to 1.9 million tC per year (annual equivalent amounts using
discounting techniques) of carbon for a marginal cost of $10 - $150 per tC. For a low carbon price of $10 per tC, the
area of cropland in conservation tillage increases about 1.5 times over the
baseline, although the average residue management is only about 43% for corn
and 56% for soybeans. Under a higher
price of $40 per tC, the area of cropland in conservation tillage rises by 2.3
times and average residue management rises to 53% for corn and 68% for
soybeans. In general, the adoption rate
of conservation practices is higher in soybean and low quality soil classes
than in corn and high quality soil classes. The fixed payment scenario is
substantially more expensive because it requires permanent adoption of
conservation tillage or no tillage. For
the fixed payment scenario that allows entrance into the program for 35%
minimum residue management, to the marginal costs of sequestering 0.2 to 1.6
million tC per year are $40-$1000 per tC.
For the fixed payment scenario that allows entrance into the program for
75% minimum residue management, to the marginal costs of sequestering 0.4 to
0.7 million tC per year are $18-$700 per tC.
These results suggest that developing policies to spur continuous
adoption of no-tillage could be fairly expensive in this region. In addition to examining potential carbon
sequestration for the region as a whole, the results show which counties within
the region have the greatest potential for sequestration under various policies
and prices. In general, the largest
gains in carbon occur in mid-productivity soils. Highly productive soils are less efficient in
no-tillage, whereas the lowest soil productivity classes have already shown
high adoption rates. The results also
suggest that leakage is not a great concern with carbon sequestration in soils.
Christy, Colin (Veris Technologies, 601 N. Broadway, Salina, KS, 67401; Phone: 785-825-1978; Fax: 785-825-6983; Email: christyc@veristech.com)
C.D. Christy*, D.A. Laird, K.A. Sudduth
This presentation discusses the measurement of soil attributes using diffuse optical reflectance in the near infrared (NIR) region. The functional groups responsible for absorption in this region of the spectrum are C-H, N-H, and O-H, allowing for the measurement of organic carbon, nitrogen, and moisture. In addition, the method is responsive to soil pH through a hydrogen bonding phenomenon that tends to shift the position of water absorption peaks. Consequently, the method can be used to measure both carbon and factors that affect the carbon cycle. Recent studies have demonstrated the utility of near infrared spectroscopy (NIRS) in a laboratory setting. This work seeks to extend the method into the field using in-situ measurement apparatus. Measurements of horizontal variations in carbon are being made with a specially designed shank while vertical changes are measured using a probe. Calibration of NIRS is performed using chemometric methods, which are based on multivariate statistics. Representative samples are analyzed using standard analytical methods to provide calibration and validation data. The calibration results of two studies using the optical shank will be presented along with preliminary results of vertical measurements using a reflectance probe. In the study where reference analysis was performed for total carbon (N=288), calibration resulted in a root mean squared error of prediction (RMSEP) of 0.35% and a correlation of 0.96 between the actual and predicted total carbon values.
Clark, Kenneth (USDA-Forest Service, P.O. Box 232, New Lisbon, NJ, 08064; Phone: 609-894-0325; Email: kennethclark@fs.fed.us)
K.L. Clark*, J. Hom, N. Skowronski, T. Wyckoff, Y. Pan, M. Patterson, J. Dighton, D. Gray
As part of a collaborative effort between the Northern Global Change Program of the USDA Forest Service, National Fire Plan-funded research, and the LANDFIRE project, we studied how fire and fuels management affects carbon dioxide (CO2) sequestration by oak- and pine-dominated forests in the Pinelands of New Jersey. We used a network of fire weather and eddy covariance towers, extensive biometric measurements, and fuel load measurements pre- and post-prescribed fire to quantify forest carbon dynamics. Despite the low nutrient status of sandy, coarse-grained soils in upland forests of the Pinelands, forest productivity was similar to other closed-canopy forests on the Atlantic coastal plain. Mean maximum net CO2 exchange during the daytime reached -20 to -25 umol CO2 m-2 s-1 during the growing season, and nighttime net CO2 exchange was a function of air and soil temperature, averaging 4 to 5 umol CO2 m-2 s-1 during the same period. Both day- and nighttime fluxes were constrained by drought, thus integrated CO2 exchange was nearly unaffected by soil moisture availability until drought stress became severe. Net CO2 exchange during the winter averaged 1.5 umol CO2 m-2 s-1 during the day and less than 1 umol CO2 m-2 s-1at night, corresponding with minimum LAI and low temperatures. Aboveground production estimated from biometric measurements indicated that ANPP was ca. 500 g m-2at all sites, and was dominated by fine litterfall production (ca. 75% of ANPP). The proportion of fine litterfall contributed by the understory increased from 7% to 43% from oak- to pine-dominated stands. Our flux tower and field-based estimates of forest productivity are consistent with FIA based estimates of NPP, but both satellite products (MODIS) and simulation models (PnET CN) overestimated forest productivity on this landscape, likely because of the difficulty in modeling soil moisture status accurately. When put in the context of annual net CO2 exchange, prescribed fire treatments released up to twice the amount of CO2 sequestered annually by these forests, equivalent to 1-3 years of fine litter production. Fire and fuels management may have longer term effects on carbon dynamics, because LAI does not recover to pre-fire levels immediately, and fires may have a “memory effect” on productivity of the understory. Our study contributes to an understanding of the environmental factors controlling forest productivity and fuel accumulation, and illustrates how fire and fuels management potentially affects carbon sequestration by forests in the Eastern US.
Coleman, Mark (USDA-Forest Service, Savannah River, PO Box 700, New Ellenton, SC, 29809; Phone: 803-725-0513; Fax: 803-725-0311; Email: coleman.m@earthlink.net)
Carbon Sequestration Through Belowground Carbon Allocation: Forest Stand Development vs. Soil Resources Availability
M. D. Coleman*
Substantial amounts of carbon can be sequestered in belowground biomass of forest plantations. However it is difficult to verify the accuracy of belowground biomass estimates on a case-by-case basis. Stand-level growth process models operating with monthly or annual time steps can be used to predict belowground carbon allocation, if they are properly validated. Many of these models assume belowground allocation is controlled by soil resource availability. Favorable soil moisture and nutrient conditions are predicted to minimize belowground allocation. As soil resource availability declines, increasing belowground allocation is predicted. Such models are scaled to regional and continental levels for carbon accounting purposes, because of limited parameter requirements and accurate predictions of aboveground production. Yet, there is strong evidence that stand development, not soil resources, predominately controls belowground allocation. Limited opportunity to validate model assumptions regarding belowground production causes concerns that errors may multiply upon scaling. To understand the relative importance of stand development and soil resource availability, we monitored above and belowground production in plots of four southern forest tree species. Biomass of stem, branch, stump, and coarse and fine roots was measured annually in control, irrigated, fertilized, and irrigated + fertilized plots. Relative root biomass consistently declined with both age and resource availability, demonstrating the need to simultaneously determine which factor predominately controls belowground allocation. When aboveground vs. belowground tissues were plotted on log-log plots to control for tree size, there were few slope differences among treatments despite more than a three-fold difference in growth. These results indicate that the relationships between above and belowground biomass is controlled mainly by development rather than soil resource availability. Furthermore, all species tended to fall on a single line. Data from literature with a variety of species, conditions and developmental stages also show very consistent relationships between above and belowground biomass. These relationships can be used to reliably predict belowground biomass as a constant fraction of aboveground biomass. Use of soil resource availability to control allocation to roots in process models introduces errors that are not consistent with a wide range of belowground data. Research that reports declining root production with increased soil resources must account for development. Prediction of belowground biomass as a proportion of stem biomass is a quantitatively accurate method of accounting for belowground carbon sequestration.
Colunga-Garcia, Manuel
(Michigan State University, 209 Manly Miles Bldg., 1405 S. Harrison Rd., East
Lansing, MI, 48824; Phone: 517-432-4463; Fax: 517-432-9415; Email:
colungag@msu.edu)
Urbanization and its Impact on the Carbon Sequestration Potential of Agroecosystems in the North Central Region
M. Colunga-Garcia*, P.R.Grace, S.H. Gage, G.P. Robertson, G.R. Safir, S. Rowshan
Current estimates of terrestrial carbon sequestration potential across the landscape are constrained by our present knowledge of land use distribution within a region. With an exponential growth in population worldwide, there is an increasing demand on rural lands to accommodate urban development. Whilst the identification of high potential regions and management strategies for sequestration of carbon in agroecosystems is an important policy objective in the mitigation of global climate change, we may be losing as much carbon in terms of productive lands as we hope to gain with conservation tillage practices. Regional and sub-regional assessments of terrestrial carbon storage over the next century which include estimates of land use change will allow us to provide policy makers with more realistic information on the impact of greenhouse gas mitigation strategies. The North Central Region (NCR) of the United States comprises the 12 states of the greater Midwest and is the major producer of corn and soybeans in the country, as well as producing half of the nation’s wheat. The potential impact of urbanization in this region was estimated using a combined analysis of urban influence buffers and urban-patch distribution for the major urbanized areas. Estimation of changes in soil organic carbon and associated greenhouse gas emissions within agricultural soils in response to management and climatic changes were conducted using a process based simulation model -- SOCRATES -- to rapidly integrate spatially explicit climate, soil and terrestrial ecosystem characterization data. The main considerations in using SOCRATES is its ability to accurately predict carbon and associated greenhouse gas emissions using non-site specific concepts of carbon cycling and biogeochemistry, its relative ease of use and minimal data input requirements. In its simplest form, SOCRATES uses annual precipitation, mean annual temperature, and soil clay content or CEC. More detailed climate inputs can be used for refining non-CO2 emissions.
Conant, Richard (Colorado State University, Natural Resource Ecology Laboratory, Fort Collins, CO, 80523-1499; Phone: 970-491-1919; Fax: 970-491-1965; Email: conant@nrel.colostate.edu)
R.T. Conant*, S. Mooney, K. Gerow
The ability of agricultural producers to compete economically against other sectors within a market for C-credits and capitalize upon soil C sequestration depends in part upon the cost of creating C-credits and our technological capability to measure the quantity of C-credits produced at low cost. Although C pools are variable and influenced by many factors, several studies have shown that field sampling and modeling procedures are effective at estimating changes in agricultural soil C sequestration at scales varying from field to nation. A few studies have tied to estimate the costs associated with measuring C-credits from agricultural soils as well as the factors that influence measurement costs. Their results suggest that a combination of modeling and field soil sampling could be a low cost method of measuring soil C-credits sold under a market based trading scheme. Modeled estimates of soil C sequestration have also been considered in programs that reward producers for changing practices rather than explicitly tying payments to the number of C credits produced. To date, little attention has been paid to the implications of the presence of uncertainty in modeled predictions of changes in soil C and their impacts on sampling and other contract costs. This paper examines the costs/benefits of reducing uncertainty associated with estimating soil C and how reducing uncertainty affects the costs of implementing agreements for soil C credits.
Conant, Richard (Colorado
State University, Natural Resource Ecology Laboratory, Fort Collins, CO,
80523-1499; Phone: 970-491-1919; Fax: 970-491-1965; Email: conant@nrel.colostate.edu)
Disturbance and
Recovery of Soil C Following Infrequent Activities
R.T. Conant*, A. Swan, K. Paustian
Short-term studies indicate
that substantial amounts of C can be lost from the soil immediately following a
tillage event. What are the implications for producers who have adopted
no-tillage, but feel that they must till to control weeds or relieve
compaction? How much of the C that has been sequestered is lost? What are the
longer-term impacts of continued infrequent no-tillage? Conversely, how does
integrating a periodic ley period into a rotation? How is C impacted by tillage
in this type of rotation? A few studies have examined the impact of occasional
tillage on soil C, but results are contradictory. If producers are to be compensated for
sequestering C in soil, the impacts of infrequent tillage should be documented
so that contracts can account for this.
We present (1) a review the literature examining the short-term impacts
of tillage on soil C, (2) review published studies documenting impacts of
infrequent tillage in predominantly no-till systems, (3) an assessment of the
impacts of ley rotations on recovery of soil C, and (4) results from a modeling
study carried out to address these questions more broadly than the published
literature allows.
Dai, Xiaoyan (Texas A&M University, Dept. of Soil & Crop Sciences, College Station, TX, 77843; Phone: 979-845-1785; Email: xdai@ag.tamu.edu)
Soil Carbon Storage and Dynamics in Response to Fire Seasonality in a Temperate Mixed-grass Savanna
X. Dai *, T.W. Boutton, M. Hailemichael, R.J. Ansley, K.E. Jessup
Prescribed fires are often utilized to manage and
manipulate the composition of plant communities. In the southern Great Plains, fire is
utilized to control woody plant encroachment into grasslands. Although these fires have the potential to
alter the quantity and quality of organic matter inputs to the soil, few
studies have evaluated the impacts of this land management technique on soil
organic carbon (SOC) storage. Therefore,
the purpose of this study was to evaluate the impact of repeated vegetation
fires and their season of occurrence on SOC storage and dynamics in temperate
mixed-grass savanna in north-central Texas.
Four fire treatments (n = 3 replicates/treatment) were
examined: summer only (SF), winter only (WF), alternate summer/winter fires
(SWF), and unburned controls. Winter
fires were conducted between January- March, and summer fires were between
August- September. Fire treatments have
been maintained for 13 yrs. In each
replicate, soil cores were taken to 1 m under three vegetation types: C3 grasses,
C4 grasses, and mesquite trees (n = 6/vegetation type). SOC and δ13C were determined
using an elemental analyzer interfaced with a continuous flow isotope ratio
mass spectrometer.
SOC storage in the 0-20 cm depth increment was
significantly greater in SF (2700 g C m-2) and SWF (2800 g C m-2)
treatments relative to the unburned controls (2400 g C m-2). In contrast, WF (2600 g C m-2) had
no significant impact on SOC compared to controls. There were no treatment effects on SOC at
depths > 20 cm. Vegetation cover type
had no significant influence on SOC storage at any depth. δ13C values of SOC increased
from approximately -21‰ at 0-10 to -15‰ at depths >20 cm. This indicates that the proportion of SOC
derived from C4 plants increased with depth, ranging from 55-60 % at
0-10 cm to 60%-90% below 10 cm. Thus,
all treatments were once strongly dominated by C4 grasses prior to
woody plant invasion during the past century.
δ13C of SOC was not affected by fire treatment implying
that fire intensity and frequency are not sufficient to significantly change
the vegetation pattern in this mixed-grass savanna.
In summary, repeated summer fires appeared to alter
ecosystem processes in a manner that increased SOC storage in the upper 20 cm
of the soil profile in this mesquite/mixed-grass savanna. Summer fire treatments (SF and SWF) increased
SOC storage by 13-17% over the past 13 yrs.
In contrast, winter fires had no effect on SOC storage. Studies of net primary productivity and soil
microbial biomass and activity are currently underway in an effort to elucidate
the mechanisms responsible for carbon sequestration in response to fire and its
season of occurrence. These results will
be of interest to scientists, policy makers, and land managers who are now
evaluating the potential for land management practices to store atmospheric
carbon and mitigate the potential for global climate change.
Das, Keshav C. (University of
Georgia, Dept of Biological and Agricultural Engineering,
Athens,
GA, 30602, Phone: 706-542-8842; Fax: 706-542-8806; Email: kdas@uga.edu)
Long-term Sequestration of Carbon in Soils using Charcoal from Renewable
Energy Production
D. Day, J. Lehmann, C. Steiner, Keshav C. Das*
Pyrolysis is the thermal treatment of biomass (e.g. peanut shells) in the absence of oxygen, which produces Charcoal, hydrocarbon vapors (BioOil), and gases (CO2, CO, H2) as primary products. It is known that Charcoal and BioOil can have beneficial properties that assist plant growth and nutrient retention in soils. The carbon in charcoal is highly recalcitrant, which allows it to persist in the environment for centuries. This makes Charcoal an easily quantifiable carbon sink. Although several biomass pyrolysis systems have been developed in the past, a complete carbon and energy balance, and related economics of this approach to carbon sequestration has not been analyzed and presented. This paper presents the energy and carbon balances in one biomass pyrolysis system for producing Charcoal and converting it to a carbon based nitrogen fertilizer (ECOSS) through an ammonia carbonation process.
Physical and chemical properties of pyrolysis Charcoal from different processes will be presented, such as charcoal carbon, volatile fraction, surface area, pore size distribution, cation exchange capacity, pH, available nutrients and total nutrients. These properties are discussed with respect to their importance to plant growth response and crop yields.
Based on the energy balance, a model is developed for computing and evaluating the potential for carbon sequestration through use of carbon-based fertilizers in commercial agriculture. The model is based on studies reported in the literature on the long-term carbon sequestration potential of Charcoal in soils.
We present here a first generation model of the energy and carbon flows in the thermochemical conversion of biomass to Charcoal and its use in agriculture. The ultimate goal is to provide a basis for comparing different Charcoal production and use technologies for agriculture and estimate the cost of sequestered carbon ($/kg-C) and the land-base required for carbon sequestration (ha/tonne-C) through this approach.
Daughtry, Craig (USDA-ARS, Hydrology and Remote Sensing Lab, Beltsville, MD, 20705; Phone: 301-504-501; Fax: 5301-504-8931; Email: cdaughtry@hydrolab.arsusda.gov)
C.S.T. Daughtry*, P.C. Doraiswamy, E.R.Hunt, J.E. McMurtrey, J.H. Prueger
Management of crop residues in agricultural fields is an important consideration for reducing soil erosion and increasing soil organic carbon. Current methods of quantifying crop residue cover are inadequate for characterizing residue cover within fields or across large regions. Our objectives were to evaluate several spectral indices for measuring crop residue cover using satellite multispectral and hyperspectral data and to categorize soil tillage intensity in agricultural fields. Landsat Thematic Mapper and EO-1 Hyperion Imaging Spectrometer data were acquired over agricultural fields in central Iowa in May and June 2004. Crop residue cover was measured in corn and soybean fields using line-point transects. Spectral residue indices using Landsat TM bands were weakly related to crop residue cover. With the Hyperion data, crop residue cover was linearly related to the Cellulose Absorption Index (CAI), which is relative depth of cellulose and lignin absorption features near 2100 nm. Three tillage intensity classes, corresponding to intensive, reduced, and conservation tillage, were correctly identified in 66-68% of fields and two classes, corresponding to conventional (intensive + reduced) and conservation tillage, were correctly identified in 80-82% of the fields. Regional surveys of soil management practices that affect soil conservation and soil carbon dynamics are possible using advanced multispectral or hyperspectral imaging systems.
Del Grosso, Stephen (USDA-ARS, Natural Resources Research Center, 2150 Centre Ave, Fort Collins, CO, 80526-8119; Phone: 970-492-7281; Fax: 970-492-7213; Email: delgro@nrel.colostate.edu)
DAYCENT National Scale Simulations of N2O
Emissions from Cropped Soils in the
S.J. Del Grosso*, W.J. Parton, A.R. Mosier, M.K. Walsh, D.S. Ojima, P.E. Thornton
Until recently, IPCC emission factor methodology, based on simple empirical relationships, has been used to estimate N and C fluxes for regional and national inventories. However, the 2005 EPA greenhouse gas inventory includes estimates of N2O emissions from cultivated soils derived from simulations using DAYCENT, a process based biogeochemical model. DAYCENT simulated direct soil N2O emissions, as well as indirect N2O emissions from NO3 leaching and N volatilization. Corn, soy, wheat, alfalfa hay, non-alfalfa hay, cotton, and sorghum were simulated at county level resolution. IPCC emission factor methodology was used to estimate emissions for the ~10% of cropped land not simulated by DAYCENT. N2O emissions from simulations of presettlement native vegetation were subtracted from cropped soil N2O to isolate anthropogenic emissions. Meteorological data required to drive DAYCENT were acquired from DAYMET, an algorithm that uses weather station data and accounts for topography to predict daily temperature and precipitation at 1 square km resolution. Soils data were acquired from STATSGO. Weather data and dominant soil texture class that lie closest to the geographical center of the largest cluster of cropped land in each county were used to drive DAYCENT. Land management information was implemented at the agricultural region level as defined by the Agricultural Sector Model. Maps of model simulated county level crop yields were compared with yields estimated by NASS for quality control. Combining results from DAYCENT simulations of major crops and IPCC methodology for remaining crop land yielded estimates of ~100 and ~70 Tg CO2 equivalents for direct and indirect, respectively, mean annual anthropogenic N2O emissions for 1990-2003.
Dell, Curtis (USDA-ARS, PSWMRU, Building 3702, Curtin Road, University Park, PA, 16802; Phone: 814-863-0984; Fax: 814-863-0935; Email: curtis.dell@ars.usda.gov)
Nitrous Oxide Emissions from Soils Rreceiving Combinations of Dairy Manure and Mineral Nitrogen Fertilizers
C.J. Dell*
The nitrification and denitrification of fertilizer and manure N applied to agricultural soils contributes substantial quantities of the greenhouse gas nitrous oxide to the atmosphere. Since manure application adds organic C as well as N, increased microbial activity in manure-amended soils could increase nitrification and denitrification activity compared to soil receiving only mineral N fertilizer. In a effort to reduce P movement to water supplies, many states now recommend or require producers to limit quantities of manure applied to the amount needed to supply crop P requirements. With lower manure application rates, the addition of inorganic N fertilizer is also needed. However, it is unclear if the use of a combination of manure and inorganic fertilizer presents a greater potential for nitrous oxide production than the use of only inorganic fertilizer. Nitrous oxide emissions were measured in 2003 and 2004 from experimental plots planted to corn. All plots received the recommended additions of N (145 kg N per hectare), but the source of the N was varied among ammonium nitrate, dairy manure, and a combination of the two. Gas samples were collected over a 30 min time span each week using small, vented chambers. Nitrous oxide concentrations were measured of by gas chromatograph equipped with an electron capture detector. Most nitrous oxide emissions occurred within two months of the spring manure or fertilizer application. By late in the growing season, emissions were near or below the minimum detection level. On several sampling dates, emissions from plots receiving some or all N as manure were significantly greater than those receiving only ammonium nitrate. Estimates of N lost as nitrous oxide during the growing seasons ranged from 1 to 6% of applied N. In 2003, total emissions were similar among N source treatments. In 2004, total emissions from plots receiving manure were significantly greater than those receiving only ammonium nitrate. However, emissions were similar between experimental plots receiving all manure compared to those where N application was split between manure and ammonium nitrate. The results suggest that manure application, even at reduced P-requirement based rates, can increase the potential for nitrous oxide production. Reducing nitrous oxide emissions following land application presents a major challenge. Additional research on the impact of manure and fertilizer application timing and techniques is needed in order to develop management practices that lead to reduced emissions.
Diamant, Adam (Electric Power Research Institute (EPRI), 1805, Arlington Blvd., El Cerrito, CA, 94530; Phone: 510-260-9105; Email: adiamant@epri.com)
Estimating and Comparing the Levelized Cost ($/ton CO2e) of Greenhouse Gas Emissions Reductions Associated with Four Different Approaches to Developing and Managing Forest Carbon Sequestration Projects
A. Diamant*
Electric utilities can implement a variety of strategies to offset their greenhouse gas emissions. One strategy that has received considerable attention is forest carbon sequestration. In recent years a number of electric utilities have invested in pilot forest carbon sequestration projects both here in the U.S. and internationally. While forest carbon sequestration appears to be a potentially low-cost way to offset GHG emissions from electric utilities, electric companies continue to wrestle with how to analyze these kinds of projects from a financial analysis perspective, and how to compare different approaches that can be used to implement these projects. The Electric Power Research Institute (EPRI) has attempted to address these issues by developing a new, “real-options”-enabled computer simulation model that is designed to estimate the levelized cost ($/ton CO2e) of GHG emissions reductions associated with four different approaches electric utilities and others can use to contract for and manage forest carbon sequestration projects. EPRI's new Greenhouse Gas Emissions Reduction Cost Analysis Model (GHG-CAM v1.1) uses an advanced discounted cash flow (DCF) analysis methodology to evaluate the revenues, costs and expected after-tax gross margins expected to flow from investments that could be made by an electric utility company in different kinds of GHG emissions reduction projects, including forest carbon sequestration. The GHG-CAM model incorporates sophisticated statistcal and economic analysis tools, including Monte Carlo simulation, real-options analysis, and decision analysis methods that make it possible to explicitly incorporate risk, statistical uncertainty and contingent decision making into the analysis of specific GHG emissions abatement strategies such as forest carbon sequestration.
Dobermann, Achim (University of Nebraska, Dept. of Agronomy and Horticulture, Lincoln, NE, 68583-0915; Phone: 402-472-1501; Email: adobermann2@unl.edu)
Changes in Soil- and Litter-C Stocks with Progressive Farming Practices in Irrigated and Rainfed Maize-Based Agroecosystems.
A. Dobermann*, J.M.H. Knops, K.G. Cassman, D.T. Walters
Litter decomposition, and changes in soil carbon stocks were quantified in three no-till cropping systems with best-management practices that produce high yields with improved input use efficiency: (a) irrigated continuous maize, (b) irrigated maize-soybean rotation, and (c) rainfed maize-soybean rotation. Measurements were conducted in production-scale fields for a period of three years. Decomposition of maize residue was similar in both irrigated and rainfed sites, but soybean residue decomposed 10 to 24% faster than maize residue. Litter-C pools increased by about 230 g m-2 during this 3-year period in the irrigated continuous corn system because of large litter-C inputs and relatively slow decomposition rates. In irrigated corn-soybean rotation, gains in litter-C during the corn phase were largely offset by losses of similar magnitude during the soybean phase. Measurements of soil organic C stocks could not detect significant changes during the first three years of no-till farming in the three cropping systems studied despite the use of a novel approach that accounted for geospatial variation in soil properties that influence soil C dynamics
Doyle, Geoffrey (USDA-ARS, Grazinglands Research Laboratory, 7207 W. Cheyenne, El Reno, OK, 73036; Phone: 4052625291; Fax: 4052620133; Email: gdoyle@grl.ars.usda.gov)
Direct Comparison of Two Systems for the Measurement of Carbon, Water and Energy Fluxes in Tallgrass Prairie
G.L.
Doyle*, W. Dugas, H. Mayeux
Micrometrological literature reflects a lack of extensive research on grassland mass and energy flux, and there remains a lacks of a standard method/measurements system. The objective of this study was to compare mass and energy fluxes of sensible heat flux density (H), latent heat flux density (LE) and carbon dioxide (CO2) from CSI-manufactured Eddy Covariance (EC) and Bowen Ratio/Energy Balance (BREB) instrumentation. The study site was a tallgrass prairie located in central Oklahoma, with above ground biomass of 8 Mg ha-1, and mean annual precipitation of 840 mm y-1. Results from co-located EC and BREB units over more than 36-month period indicated that both systems demonstrated similar seasonal patterns, yet the EC measured 30% lower values for H and LE when compared to the BREB. The sum of EC H and LE fluxes were 20-70% less than what was required to close energy balance. On days with flux greater than 0, BREB CO2 flux was 2 - 10% more positive (more loss) when compared to the EC. The tallgrass prairie site typically was a source of CO2 for up to 8 months each year, and a sink during the other 4 months -- where the uptake rates were sufficiently high enough to produce average annual uptake. Average daily CO2 flux for the entire period was approximately -0.4 g CO2 m-2 d-1 (small sink).
Dria, Karl (Purdue University, 550 Stadium Mall Dr., W. Lafayette, IN, 47907; Phone: 765-494-3274; Fax: 765-496-1210; Email: kdria@purdue.edu)
Dynamics of Biopolymer Turnover in Soil Physical Fractions Following Land-Cover Change in a Subtropical Savanna
T.R. Filley, K.J. Dria*, D.E. Gamblin, J. Liao, T. Boutton, J. Jastrow
Changes in the apportionment of organic carbon and nitrogen among soil physical fractions following land-cover shifts are of critical importance to the debate surrounding the capacity of terrestrial ecosystems to store or release greenhouse gases. For example, the difference between the mean residence times (MRTs) of light particulate organic matter (POM) vs. silts and clays is typically quite large, with silt and clay associated organic matter having the longest MRTs and the greatest likelihood to contribute to long term carbon storage. A few studies in agricultural and forest systems have demonstrated that biopolymer chemistry also varies along physical, as well as density, fractionation gradients. We quantified changes in biopolymer (lignin, suberin and cutin, and hydrolysable amino acids) chemistry of size and density fractionated soil from the Rio Grande Plains of Texas where C4 grasslands (d13C = -14 %) have undergone succession to subtropical thorn woodland dominated by C3 trees/shrubs (d13C = -27 %) over the past 150 years. This natural isotopic distinction was used to determine MRTs of free light organic matter (density less than 1.0 g/cc), macroaggregate (greater than 250 um), microaggregate (53-250 um) and silt+clay (less than 53 um) fractions which were then related to their specific biopolymer chemistries. Our results illustrate that lignin and aliphatic biopolymers (as measured by hydroxyl fatty acids) are apportioned differently among size/density fractions and along the successional chronosequence. Lignin is incorporated into all soil fractions soon after woody encroachment, whereas aliphatic components are slow to be incorporated in the silt and clay fractions. The lignin components that do become associated with silts and clays are, in general, highly oxidized. Differences in foliar chemistry among the plant sources indicate selective movement of leaf cutins into POM, macro- and microaggregate fractions, but not into free or intra-aggregate silts and clays. Selected analyses of silt and clay fractions for hydrolysable amino acids showed differences along the chronosequence, with total hydrolysable amino acids comprising 30-45% of total nitrogen. It is possible that amino and phenolic compounds are tightly bound to the silts and clays (the fractions with the longest MRT) and repel the more hydrophobic and less water soluble cutin and suberin monomers, thereby restricting turnover. These results provide new insights regarding the interactions between soil structure, chemistry, turnover, and preservation of soil organic matter.
Engel, Richard (Montana State
University, Dept. of Land Resources and Environmental Sciences, Bozeman, MT,
59717-3120; Phone: 406-994-5295; Fax: 406-994-3933;
Email: engel@montana.edu)
Nitrous Oxide Emissions from Soils under Cropping Systems
Adapted for the Semi-arid
M.P. Dusenbury, R.E. Engel*, P. Miller, R.L. Lemke
Nitrous oxide is powerful greenhouse gas and contributes to degradation of ozone in the atmosphere. Although agriculture has been identified by the Intergovernmental Panel on Climate Change (IPCC) as the major anthropogenic source of N2O emissions, field measurements of N2O are limited for agricultural systems, particularly in the Northern Great Plains. This study was undertaken to learn more about N2O seasonal emission patterns and levels from cropping systems adapted for the Northern Great Plains, and to determine if the IPCC methodology for estimating fertilizer N induced N2O losses is accurate for this region. Five cropping systems with varying N fertilizer regimes were sampled from spring thaw in March until freeze up in December. The greatest activity of N2O emissions for this sampling year occurred during a 10-week period following N fertilization (April 13). Emissions over the period averaged 73% of the sampling year total. Emission levels in the spring were influenced by soil moisture and N substrate. Nitrous oxide flux rates from fallow-wheat and pea-wheat rotations under high N fertility (200 kg ha-1 available N) were related to water-filled pore space by a quadratic relationship. The relationship showed emissions increasing rapidly after water-filled pore space exceeded 50%. Total sampling year losses of N2O-N were < 0.10 kg ha-1 for all cropping systems. Fertilizer N induced losses ranged 0.02 to 0.12%, and were greater than one order of magnitude below IPCC predicted losses using the 1.25% default value.
Esuola, Adeyemi (University of Guelph, 38-252 Stone Road West, Guelph, ON, N1G 2V7, Canada; Phone: 519- 824 4120 ext 53625; Fax: 519-767-1510; Email: aesuola@uoguelph.ca)
Economic Analysis of Efficient Risk Allocation in Contracts to Sequester Carbon in Agriculture and Forestry
A. Esuola*
Carbon that has been sequestered either in the soil or forest is reversible. The reversibility could be due to a course of action taken by the seller of the carbon or could be due to a natural hazard like a fire or pest outbreak. When the sequestered carbon is released the question that needs to be asked is, who is responsible for the loss of the carbon? Maybe if the loss of the carbon is deliberate, one could argue that the seller of the carbon should be liable for the loss. What about when the loss is due to natural causes? Who should be held responsible?
Contracts are now being negotiated between farmers or foresters and large GHG emitters that establish the conditions under which carbon is to be sequestered by the farmer or forester. The conditions include the price of carbon, the contract length, and liability period for temporary or permanent credits. Unresolved issues in the implementation of the Canadian offset system include the length of a permanent credit and what happens when a permanent credit is reversed. With a temporary credit, there are questions surrounding how long maintenance can generate credits and what happens if a large emitter defaults on replacing a temporary credit with a permanent credit. One of the more difficult conditions to be negotiated is the means by which risk associated with the release of stored carbon from a random act of nature or a deliberate act by the seller of carbon should be allocated. The different options that have been advocated in allocating this risk of carbon release include seller liability, buyer liability or shared seller-buyer liability. The applicability of any of these will depend on the compliance and enforcement environment. A seller (buyer) liability may be applicable in a strong (weak) compliance and enforcement environment. Other options of risk allocation include a rental approach or carbon banking.
The purpose of this paper is to examine the optimal allocation of risk in a contract designed to sequester carbon. The focus is on the risk of both intentional and unintentional release of stored carbon. The paper begins by reviewing how an efficient contract allocates risk theoretically. Alternative means of allocating risk between the buyer and seller of a carbon contract are then outlined followed by a discussion of the advantages and disadvantages of the approaches. The paper concludes with policy implications.
Fabrizzi, Karina (Kansas
State University, 2004 Throckmorton Plant Sciences Center, Manhattan, KS,
66502; Phone: 785-532-7106; Email: kfabrizz@ksu.edu)
K.P. Fabrizzi*, C.W. Rice, A. Schlegel, D. Sweeney, D. Peterson, C. Thompson
Management practices such as crop rotation, tillage, and fertilization can affect soil organic C levels, thus having a positive impact in the reduction of atmospheric CO2 levels. Evaluation of these practices with long-term experiments is needed to know the effect of agricultural management on soil C sequestration. The objective of this study was to study the effects of crop rotation, tillage, and fertilization on soil C sequestration in Kansas. Soil organic carbon (SOC) was measured at 0-5, 5-15, and 15-30 cm depth in four long-term experiments with different years and with different tillage systems, at four locations in Kansas: Tribune (16 yr, tillage effects)(Aridic Argiustolls), Hays (37 yr, tillage and N effects) (Typic Argiustolls), Ashland (23 yr, crop rotation and tillage effects) (Cumulic Haplustolls), and Parsons (20 yr, tillage and N effects) (Mollic Albaqualfs). Tillage treatments were: conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Nitrogen rates were 0, 22, 45 and 67 kg N ha-1in Hays (0-N, 22-N, 45-N and 67-N), and 0 and 140 kg N ha-1in Parsons (0-N and 140-N). Crop rotations evaluated at Ashland were: sorghum/sorghum, soybean/sorghum, soybean/soybean, wheat/soybean and wheat/wheat. Data from Hays showed a positive soil C sequestration rate under NT at 0-15 (0.020 Mg C ha-1 yr-1) compared to CT (-0.055 Mg C ha-1> yr-1) and RT (-0.036 Mg C ha-1 yr-1). Rates were affected by the addition of N fertilizer, being greater and positive in the 67-N treatment (0.001 Mg C ha-1 yr-1). At Parsons, NT had greater SOC contents at 0-5, 0-15 and 0-30 cm when compared with CT and RT. Soil C sequestration rates at 0-15 cm were 0.229 Mg C ha-1 yr-1 for NT, 0.166 Mg C ha-1 yr-1 for RT, and 0.1398 Mg C ha-1 yr-1 for CT. At Tribune, NT had higher SOC contents (10.5 Mg C ha-1) at 0-5 cm compared with CT (8.7 Mg C ha-1) and RT (9.8 Mg C ha-1). Rates of C sequestration calculated with respect to the native prairie sod at 0-15 cm were negative with the lowest loss of C under NT systems. Data from Ashland showed a significant effect of rotation and tillage on SOC content at 0-15 cm. Wheat/wheat rotation had the greatest SOC of 31.6 Mg C ha-1, with the lowest under soybean/soybean rotation (21.1 Mg C ha-1). Also, NT treatments (28.4 Mg C ha-1) had similar SOC than RT (27.4 Mg C ha-1) but higher than CT (24.4 Mg C ha-1).
Fabrizzi, Karina (Kansas
State University, 2004 Throckmorton Plant Sciences Center, Manhattan, KS,
66502; Phone: 785-395-6018; Email: kfabrizz@ksu.edu)
K.P. Fabrizzi*, C.W. Rice, A. Schlegel, D. Sweeney, D. Peterson, C. Thompson
Management practices such as crop rotation, tillage, and fertilization can influence soil biological activities through their effects on the quantity, structure, and distribution of soil organic matter (SOM). The effects of these management practices on soil C fractions were evaluated in this study. Soil samples were taken from four long-term experiments with different years under tillage systems, at four locations in Kansas: Tribune (16 yr, tillage effects) (Aridic Argiustolls), Hays (37 yr, tillage and N effects) (Typic Argiustolls), Ashland (23 yr, crop rotation and tillage effects) (Cumulic Haplustolls), and Parsons (20 yr, tillage and N effects) (Mollic Albaqualfs). Soil organic carbon (SOC), microbial biomass (SMB-C) and mineralizable C (MinC) were measured at 0-5 and 5-15 cm depth. Tillage treatments considered during the study were: conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). N rates were 0, and 67 kg N ha-1 in Hays (0-N and 67-N), and 0 and 140 kg N ha-1 in Parsons (0-N and 140-N). Crop rotations evaluated at Ashland were wheat/soybean and wheat/wheat. In Hays, CT and RT treatments had greater SMB-C fractions than NT at 0-N treatment at 0-15 cm. MinC was greater under NT than the other tillage systems at 67-N treatment. Tribune data showed a greater proportion of C in the labile pools (SMB-C and MinC) under NT and native prairie treatments at 0-15 cm. In Ashland, SMB-C represented between 2.2 and 2.8%, and MinC between 25-30% of the soil organic carbon in the wheat/soybean rotation. Values for wheat/wheat rotation were 1.0 to 1.3 % for SMB and 28 to 34% for wheat/ wheat rotation.
Fiedler, Jeff (NRDC, 1200 New York Avenue NW #400, WashingtonDC, 20005; Phone: 202-289-2419; Fax: 202-789-0589; Email: jfiedler@nrdc.org)
Growing Energy: How Biofuels Can Help End America's Energy
Dependence
J. Fiedler*
A coalition of researchers analyzed the technical and economic potential of cellulosic biofuels production, and the R&D and policies required to achieve this potential. The potential is significant and can be achieved in a way that achieves environmental benefits (assuming sufficient protections for air quality and other issues), provides new markets for farmers, and is complementary to existing corn ethanol operations.
Fiedler, Jeff (NRDC, 1200 New York Avenue NW #400, WashingtonDC, 20005; Phone: 202-289-2419; Fax: 202-789-0589; Email: jfiedler@nrdc.org)
J. Fiedler*
The United States and other countries are considering policies to address global warming. Countries participating in the Kyoto Protocol are limiting emissions in ways that will have at least indirect ramifications for the agriculture sector. Although the current U.S. administration is opposed to mandatory limits, most observers agree that such an approach is likely at some time in the future. The McCain-Lieberman bill (Climate Stewardship Act) provides one indication of future U.S. policy directions. It received 43 votes in the U.S. Senate in October 2003 and continues to be advocated by its sponsors. This paper surveys economic analyses of this and related proposals in order to shed light on the agriculture sector in a carbon-constrained future. Research gaps and priorities are also identified. The agriculture sector faces threats and opportunities in a carbon-constrained world. For a number of reasons, the sector is likely to be largely exempt from direct regulation under a carbon cap. Nevertheless, mandatory policies may increase the cost of natural gas, on-farm diesel, and other energy inputs for the sector, and thus have the potential to affect farm income and production decisions. Mandatory policies also may drive new energy markets for farmers, and carbon offset projects may provide additional revenue opportunities. A carbon cap will provide an incentive for lower-carbon energy sources: corn ethanol and to an even greater extent cellulosic ethanol; on-farm wind power; and methane capture and use. Offset projects may reward soil and forest carbon sequestration and reduced nitrous oxide emissions from fertilizer application. The large number of elements involved makes understanding the agriculture sector’s role in climate policy a complex undertaking. Current studies do not provide a comprehensive or sophisticated understanding of the opportunities and risks for the future.
Fiyalkovskyy, Oleksandr
(Tetiiv Institute of Agroecology and Biotechnology, 15, Stepovoy Street, Kashperivka, Tetiiv area, Kyiv region, 09812,
Ukraine; Phone:
+380 4460 26370; Fax: +380 4460 26370; Email: fiyalko_agro@ukr.net)
Balance of Carbon in Natural and Anthropogenic Ecosystems of Forest-Steppe Zone of Ukraine
O. Fiyalkovskyy*
СО2
balance in ecosystem and entrance of this greenhouse gas into the atmosphere is defined by correlation of
velocities of two global processes – СО2 emission as a result of respiration of
soil heterotrophic
microorganisms
and animals, decomposing
a fall, and СО2
flow in the form of pure initial production of plants. In the natural
ecosystems flow of the carbon predominates, or value
of СО2
balance is close to zero. Agrocenosises are traditionally considered as one of
the main sources of СО2 and the other greenhouse gases in the
atmosphere owing
to violations of carbon rotation in ecosystem leading to intensification of
mineralisation of soil organic substance. In order to correct global СО2 emission from arable soils
of Ukraine it is necessary to estimate an influence of the most frequently used farming methods in
agriculture on carbon balance in agrocenosises. Taking into consideration the
necessity of reduction of greenhouse gases concentration in atmosphere and binding them together in
stable forms of organic substance, farming methods, providing the carbon balance
with no deficit, should
be revealed. Purpose of the present research was to study the carbon balance in ecosystem and in the soil under the
cultivation of crops and also carbon accumulation under plowland grassing and
forest overgrowing of arable soils. The research was conducted on the grey
forest soils 10
km west of village Volodarka. Carbon balance in crops of
maize, spring barley and winter wheat was calculated on field experiment plots,
differing by crop rotation type, fertilizer doses and type of soil cultivation
during period from 1999 to 2003. Influence of artificial plowland grassing was
studied in 2003-2004. Compound of meadow fescue (Festuca pratensis), timothy (Phleum
pratense) and meadow clover (Trifolium
pratense) was sowed on the old-arable eroded grey forest soils in 1991. Influence of
natural forest restoration
grey forest soil was studied on the plot of secondary mixed forest measuring 10
x 10 m from 2000 to 2004. Average age of the trees 35-45 years. Contribution of
root
respiration into СО2 emission from soil was studied. It
was calculated carbon
balance in natural and agroecosystems. Estimation of carbon balance in
agroecosystems on grey forest soils revealed that even under low level of the
agrotechnics without fertilizer use negative carbon balance in agrocenosis and
in soil is observed only in black fallow under spring barley cultivation. In
all the rest of agrocenosises (winter wheat, maize, buckwheat) carbon balance
was with no
deficit. In the 13 years of plowland grassing the content of organic carbon in the 0 – 0.25 m soil
layer increased by 22-25%, and the reserves of microbial carbon increased by
two times. Thus, farming method, allowing to change carbon balance in the soil
radically toward its increase, without completely excluding the soil from
agricultural rotation,
is artificial grassing of soil. Plowland grassing of arable soils can be one of
the prospective methods of reducing СО2 concentration in the
atmosphere and carbon
accumulation in the soil, particularly in natural zones, where steppe
associations are natural vegetation. In the time of resumption of natural
forest vegetation on the old-arable eroded grey forest soils doubling of organic carbon reserves can be
expected.
Fonte, Steven (University of California-Davis, Dept. of Plant Sciences, Davis, CA, 95616; Phone: 530-754-7537; Email: sjfonte@ucdavis.edu)
Influence of Earthworm Activity and Cropping Systems on C Stabilization,
N Dynamics, and Greenhouse Gas Fluxes
S.J. Fonte*, A.Y. Kong, C. Van Kessel, P.F. Hendrix, J. Six
Earthworms are key regulators of soil structure and C turnover within many ecosystems, however, their influence on C and N fluxes in different cropping systems remains poorly understood. By manipulating population densities of the endogeic earthworm Aporrectodea rosea in the field, this study examines the influence of earthworms on greenhouse gas fluxes and the incorporation of C and N into soil aggregates. In situ microcosms were used to establish three levels of earthworm activity: no earthworms, background, and elevated (5 earthworms per microcosm). These treatments were located within three corn-tomato systems: conventional, organic, and an intermediate low-input system (with legume cover crop and mineral nutrient inputs). A 15N and 13C labeled cover crop was incorporated into the soil in the organic and low-input systems, while 15N labeled fertilizer was applied in the conventional system. For all treatments, total C, 13C, total N and 15N were quantified in three aggregate size classes: macroaggregates (greater than 250 µm), microaggregates (53 - 250 µm) and the silt and clay fraction (less than 53 µm). In addition, microaggregates were isolated from within macroaggregates to determine the relative role of this fraction in stabilizing C. Carbon dioxide and nitrous oxide were measured throughout the growing season using gas flux chambers in the field. Preliminary analyses demonstrate a significant effect of management system on CO2 and N2O fluxes. The highest flux for N2O (0.11 µMol N2O m-2 min-1) was observed in the conventional system in June of 2004, while the two cover crop systems exhibited the highest CO2 fluxes (mean flux of 803.2 µMol m-2 min-1) on the same sampling date
Franzluebbers, Alan
(USDA-ARS, Watkinsville, GA, 30677; Phone: 706-769-5631; Fax: 706-769-8962;
Email: afranz@uga.edu)
Soil Organic Carbon Sequestration in Pastures of the Southeastern USA: Knowledge and Gaps
A.J. Franzluebbers*
Agricultural land in the southeastern
USA encompasses approximately 45 Mha, of which 19 Mha is devoted to
pasture. This extensive resource has the
potential to sequester soil organic C (SOC), especially following historical
conversion of land, first from native forest to intensively cultivated cropland
and more recently from intensively cultivated cropland to pastureland. This paper reviews recent research reporting
SOC changes with pasture management and identifies significant gaps in our knowledge
of how pasture management might affect SOC and emission of greenhouse
gases. Management factors affecting SOC
include land use, forage type, fertilization, and forage utilization. Establishment of perennial grass pastures
could sequester SOC at rates of 0.2 to 1.5 Mg C/ha/yr, depending upon
management variables. Although some
information on SOC sequestration and greenhouse gas emission is available,
there is a great need to conduct more research on the diversity of pasture
systems relevant to agriculture in the southeastern USA.
Franzluebbers, Alan
(USDA-ARS, Watkinsville, GA, 30677; Phone: 706-769-5631; Fax: 706-769-8962;
Email: afranz@uga.edu)
Soil Organic Carbon Sequestration in Cotton Production
Systems of the
A.J. Franzluebbers*, H.J. Causarano, D.W. Reeves, J.N. Shaw, M.L. Norfleet
Conservation-oriented agricultural management systems have been suggested to sequester soil organic C (SOC), improve soil quality, and increase crop productivity. Our objective was to summarize and synthesize available literature related to SOC sequestration in cotton production systems of the southeastern USA. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.55 Mg C/ha/yr. Variation was large, but was expected based on the diversity of soils, cropping systems, and experimental conditions that occurred among locations. By implementing no tillage continuously for 10 years on a typical soil in the southeastern USA, SOC to a depth of 20 cm could be expected to increase from 25 Mg C/ha initially to 30 Mg C/ha (19% increase). More diverse rotations of cotton with high-residue-producing crops such as corn and small grains would sequester greater quantities of SOC than continuous cotton. Available data suggested that no-tillage cropping with a cover crop sequestered 0.67 +/- 0.63 Mg C/ha/yr, while that of no-tillage cropping without a cover crop sequestered 0.34 +/- 0.47 Mg C/ha/yr. Conservation tillage with cover cropping is an appropriate technology for SOC sequestration and complements additional benefits of reducing soil erosion, reducing fuel cost, increasing biological diversity, and improving nutrient cycling.
Franzluebbers, Alan (USDA-ARS, Watkinsville, GA, 30677; Phone: 706-769-5631; Fax: 706-769-8962; Email: afranz@uga.edu)
Greenhouse Gas Contributions and Mitigation Potential in
Agricultural Regions of
A.J. Franzluebbers*, R.F. Follett, E.G. Gregorich, J.M.F. Johnson, M.A. Liebig, D.A. Martens, S.J. Del Grosso, M.D. Jawson
Agricultural land in North America is managed with a diversity of techniques and technologies to achieve a wide range of goals. Overlaying this management diversity onto an environmentally and ecologically diverse landscape leads to a complex arrangement of how agricultural management systems might contribute to and mitigate greenhouse gas emissions. This paper reviews regionally-specific information available on soil organic C sequestration and greenhouse gas emission in agriculture systems of North America. Adoption of conservation tillage has been widely implemented and mean values of soil organic C sequestration among the five major regions ranged from -0.07 Mg C/ha/yr in the northeast to 0.48 Mg C/ha/yr in the southeast. Actual field measurements of nitrous oxide emission and methane uptake by soils have not been widely determined, and this lack of information suggests a key area requiring further research. Modeling efforts have allowed estimation of regional differences in net global warming potential of greenhouse gas emission in agricultural systems. Research and implementation needs to better describe greenhouse gas contributions and mitigation potential of agricultural systems in North America have been identified.
Friend, Alexander L. (USDA-Forest Service, North Central Research Station, Houghton, MI, 49931; Phone: 906-482-6303x22; Fax: 906-482-6355; Email: afriend@fs.fed.us)
A. L. Friend*
The Northern Institute of Applied Carbon Science (NIACS) is a partnership among the USDA Forest Service (North Central and Northeastern Research Stations), the Forest Carbon Consortium (within the National Council for Air and Stream Improvement) and Michigan Technological University. The organization seeks to advance carbon management (both bioenergy and sequestration) in northern forests of the United States and Canada by connecting end-users (land managers and policy makers, carbon credit purchasers) with the necessary research information to manage forests for carbon, and by connecting researchers with the needs of the end user. This bridging function is being accomplished by direct and active involvement of NIACS in three key output areas:
(1) enhancing research effectiveness by playing an active role in identifying research needs and developing research partnerships, (2) generating or assembling key research information to aid carbon management, and (3) improving awareness of carbon management techniques and opportunities. Current activities of NIACS in these three areas will be discussed, as will opportunities for partnering in the realm of carbon management in northern forests.
Fronning, Bradley (Michigan State University, 286A Plant and Soil Sciences Building, East Lansing, MI, 48824; Phone: 517-355-0271; Email: fronning@msu.edu)
Carbon Sequestration Practices in Silage Corn - Soybean
Cropping Systems in
B.E. Fronning*, K.D. Thelen, D.H. Min
Research was conducted over three years (2002-2004) at Michigan State University in East Lansing, MI (N 42.42, W 84.28) and at the Upper Peninsula Experiment Station near Chatham, MI (N 46.29, W 86.76) to evaluate the effectiveness of cover crops and manure systems for carbon sequestration at different latitudes. The experiment consisted of six treatments applied to soybean and silage corn at East Lansing: composted manure, fresh manure, winter rye cover crop, winter rye + composted manure, winter rye + fresh manure, and an untreated check. Treatments at Chatham were applied to silage corn and forage soybean in 2002 and 2004 and silage corn in 2003. Winter rye cover crop failed in 2002 at Chatham so treatments containing winter rye were changed to include forage soybean instead. In 2002 and 2004 treatments consisted of composted manure, fresh liquid manure, and an untreated check applied to silage corn and forage soybean. In 2003 a winter rye cover crop was established so the treatments were composted manure, fresh liquid manure, winter rye cover crop, composted manure + winter rye, fresh liquid manure + winter rye, and an untreated check. Soil samples were collected in the spring of every year plus the fall of 2004 to determine, total carbon, total nitrogen, phosphorous, particulate organic matter, bulk density, and pH. A gas chamber was placed in each plot to measure the flux of greenhouse gases in an enclosed system. Over 5400 total gas samples were collected over the three year period between both locations. Winter rye alone and the untreated check were the only treatments which failed to increase soil carbon levels at East Lansing between the springs of 2002 and 2004. Treatments containing composted manure increased soil carbon levels more than those containing fresh manure. Winter rye + fresh manure was the only treatment at Chatham which did not result in increased soil carbon levels. Similar to East Lansing, treatments containing composted manure appeared to increase soil carbon levels faster. Efficiency of these treatments in sequestering carbon was affected by latitude. Less applied carbon was required at Chatham to increase soil carbon than at East Lansing. Gas flux was affected by treatments at certain times of the growing season. Treatments had minimal affects on crop yields at both locations.
Gage, Stuart (Michigan State University, 207 Manly Miles Bldg., 1405 S. Harrison Rd., East Lansing, MI, 48824; Phone: 517-355-2135; Fax: 517-432-9415; Email: gages@msu.edu)
A Modeling Application Integrative Framework for Regional Simulation of Crop Productivity, Carbon Sequestration and Greenhouse Gas Emissions
S.H. Gage*, M.
Colunga-Garcia, P.R. Grace, H. Yang, G.R. Safir, G.P. Robertson,
A. Shortridge, A. Prasla, A. Ali, S. Del Grosso, P. Wilkins
A Modeling Applications Integrative Framework (MASIF) has been
developed to support the analysis of regional simulation models. A framework is
necessary because of the scale of the inputs to such models and the results
derived from experiments with model simulations. The essence of the framework is to enable management
and analysis of data inputs to models and resulting output from models. Our
approach is to utilize commercial applications that have flexible and scaleable
capacities to support analysis in three basic arenas: data management, mapping and statistics. Oracle was selected to support the database
management function. ESRI ArcGIS, was selected to perform geographic
manipulations. SPlus was selected as the
preferred statistical analysis utility to conduct analysis of model input and
output. Each of these software environments can operate across computational
platforms. The Microsoft OS was selected as our platform choice and the
VisualNet programming environment is utilized to knit database, mapping and
statistical analysis into the MASIF framework. During the CASMGS enterprise we
have held five workshops at Michigan State University designed to support model
developers from Colorado, Nebraska, and Alabama to integrate regional crop and
carbon simulation models into MASIF. The
following models have been linked to MASIF: Muchow-Sinclair maize, Sinclair
soybean, DSSAT, DAYCENT, and SOCRATES. The crop simulation models require daily
meteorological input and can output growth and productivity estimates, from
daily to seasonal time scales, based on analytical requirements. We have successfully linked crop models to a
daily meteorological database for the North Central Region (NCR). This database comprises 32 years (1970-2001)
of daily maximum temperature, minimum temperature, precipitation and solar
radiation from 1053 point location encompassing the NCR contains over 11
million records. Model results from a single experimental simulation can
produce a similar or larger output data stream. The DAYCENT or SOCRATES carbon
models do not require the same high temporal scale input as daily crop models
but require historical and current land use, climate and soil patterns and
simulation may require large runs at annual time steps for long time series
over large geographic regions. To accommodate carbon sequestration simulations,
the National Land Cover Data has been integrated to estimate the percentage
land use/land cover at the county level for the NCR. We have used this
information along with the NPP determinations to run the SOCRATES model to
estimate the soil carbon dynamics on a county-wide basis for the NCR region in
the past, present and future (assuming several global warming scenarios). This
comparative framework will also be used in the analysis of other models. We are
in the process of enhancing accuracy of regional simulations of carbon
sequestration through the integration of remote sensing derived variables into
crop simulation models. Remote sensing provides the capability for observing
large areas, at varying spatial and temporal scales, for attributes that can be
used to estimate aboveground biomass and the proportion of exposed soils. We
have developed a capacity to utilize MODIS data and are in the process of
integrating this data into simulation models via MASIF. Remote sensing
estimates will be used as drivers to replace simulated biomass or LAI outputs
from crop physiological growth and development models. In summary, the MASIF
environment enables a model analyst to conduct regional runs and experiments
using any of the models integrated into MASIF.
Galang, Jeff (Virginia Tech, 427 Smyth Hall, Blacksburg, VA, 24060; Phone: 540-641-2212; Email: jgalang@vt.edu)
Using Geographic Information Systems (GIS) to Assess Virginia’s Best Options for Sequestering Carbon through Improved Land-Use Management
J.S. Galang*, C.E. Zipper, S.P. Prisley, J.M. Galbraith, R.H. Wynne
Numerous process-based models exist that assess carbon fluxes over time; however, few studies have focused on assessing the potential for carbon sequestration over broad geographic areas through specific land management changes using the concept of ‘additionality.’ This study uses Geographic Information Systems (GIS) to estimate the additional CO2 that could be sequestered in the state of Virginia through alternative management of agricultural and forested lands. Three primary management changes are considered: conversion of marginal agricultural land to long-term forest cover, conversion of tillage practices for row crops, and changes in forest management. Additional considerations include afforestation of agricultural lands within riparian zones and assessment of the rate of forest loss over time. Downloadable data from public agencies were gathered to develop a spatial database of relevant factors and manipulated through a variety of raster overlay techniques to derive estimates of potential carbon sequestration within Virginia’s various ecoregions. Because the conversion from marginal agricultural lands to forest cover is long-term, this land-use change has the highest potential for sequestration. The highest amounts of potential sequestration from this practice are in the Tidewater region of Virginia (wet soils) and in the Ridge and Valley region (steep, shallow soils). Final maps of carbon sequestration potential can then be used to aid in the decision of which management changes to implement and in what region.
Gassman, Philip (Iowa State University, 560E Heady Hall, Center for Agric, Ames, IA, 50011-1070; Phone: 515-294-6313; Fax: 515-294-6336; Email: pwgassma@iastate.edu)
Climate Change Projection Impact on Soil Carbon and Other
Environmental Indicators for the
P.W. Gassman*, C.J. Anderson, G.S. Takle, M.K. Jha, R.M. Cruse
Coupled atmosphere-ocean models project future climate changes in response to changes in forcing due to greenhouse gas increases, changes in atmospheric aerosol concentrations, and land-use changes. Results of these models are used either directly or indirectly (by driving regional climate models) to project changes in hydrologic responses of watershed systems and crop growth. However, comparatively few studies have assesses impacts of climate change on soil organic carbon (SOC) sequestration and related environmental indicators. Our goal is to provide an initial assessment of a new climate change projection on SOC sequestration and other environmental impacts such as soil erosion losses for the Upper Mississippi River Basin. We use climate change projections generated by the Goddard Institute for Space Studies (GISS) 4ox3o Atmospheric-Ocean Model (AOM), which will be used as part of the 2007 IPCC climate change analysis. SRES scenarios “A1B” and “B1”, corresponding to atmospheric CO2 concentration levels 2.0 and 1.5 times as much of the 2000 level, respectively, are used for our analysis. We compare conditions for a future climate period of 2081-2100 with those of a 20th century “contemporary climate” baseline represented by the period 1961-2000. SOC sequestration, soil erosion rates, and other environmental indicators will be estimated with an enhanced version of the Environmental Policy Impact Climate (EPIC) model, which includes a carbon cycling routine based on the approach used in the Century model. The EPIC simulations will be performed within an existing modeling framework developed at the Center for Agricultural and Rural Development for over 40,000 agriculturally related points, as identified in the 1997 National Resource Inventory (NRI). Changes in SOC and other environmental indicators will be aggregated to the USGS 8-digit watershed level and will be reported as relative changes between the two future climate scenarios and the 20th century baseline.
Gehl, Ron (Kansas State University, Dept. of Agronomy, Manhattan, KS, 66506-5501; Phone: 785-532-7212; Fax: 785-532-6094; Email: rgehl@ksu.edu)
Landscape Position and Watershed Treatment Impacts on Spatial Distribution of Soil Organic Carbon
R.J. Gehl*, C.W. Rice, M.D. Ransom, R.S. Blaisdell, J.W. Stuth
Evaluating the influences of topography and watershed management of native grasslands on soil C content is an important component to improving our overall understanding of terrestrial soil C dynamics. A joint effort of Kansas State University and Texas A&M University began in 2002 to determine the effects of landscape position and watershed treatment on soil organic carbon (SOC) content at the Konza Prairie Biological Station (Manhattan, KS). Soil samples were collected at depths of 0-5, 5-15, and 15-30 cm in each of 6 watersheds. Each watershed had a distinctive treatment including a combination of grazing or no grazing and one of 3 prescribed burn sequences: annual, 4-yr interval, or 20-yr interval. Soil samples were collected at the interfluve, sideslope, footslope, and toeslope landscape positions. Samples were analyzed for %C using near infrared reflectance spectroscopy (NIRS). Initial comparisons of 4 watersheds (non-grazed, 20-yr; grazed, 20-yr; non-grazed, 4-yr; and non-grazed, 1-yr) across all slope positions indicated that only the non-grazed annually burned watershed had significantly lower (P = 0.05) C content (2.68 %C) at the surface 0-5 cm, and no differences were detected at the 5-15 or 15-30 cm depths. No significant differences in slope position were detected in the surface 0-5 cm, while the toeslope position of three non-grazed watersheds had less C in the 5-15 cm depth and the non-grazed, 20-yr burn watershed had less C at the toeslope in the 15-30 cm depth. Comparisons of slope position across the four watersheds indicated differences in SOC only in the 5-15 and 15-30 cm depths. Future research will include additional sampling at the watersheds and analysis of samples using dry combustion.
Gershenson, Alexander (University of California-Santa Cruz, UCSC Environmental Studies, 1156 High St, Santa Cruz, CA, 95064; Phone: 831-252-3514; Email: agersh@ucsc.edu)
Soil Moisture and Temperature Constraints on Fine Root Dynamics, Plant Growth, and Photosynthetic Activity in a Mediterranean Forest in the Sierra Nevada, CA
A. Gershenson*, L. Misson, J. Tang, A. Goldstein, W. Cheng
Root turnover is one of the major pathways for terrestrial carbon cycling. Although many investigations have focused on determining how various factors affect fine root dynamics, few have examined the effects of intra-seasonal variability associated with Mediterranean climates on fine root and related aboveground growth dynamics. Data collected during the 2003 growth season suggest that phenological development of Ponderosa pine-dominated ecosystems of Sierra Nevada may be highly dependent on prevailing climatic conditions. We monitored fine root development, trunk thickening, shoot and needle elongation, and shrub LAI changes throughout the season, as well as soil moisture, and soil and air temperature and canopy level photosynthesis. The site is characterized by cold, wet winters and extremely hot and dry summers. The onset of growth in this ecosystem appears to be controlled by the increase of the daily minimum temperatures above 5 degrees C in the middle of May, and the end of the growing season appears to be controlled by the decrease of available soil moisture to below 15% in the middle of July. We also monitored canopy photosynthetic activity, which dramatically increased in the beginning of Spring and decreased by the end of June. Current available climate modeling projections focused on this area of California predict significant snow accumulation decreases, and increases of springtime temperatures by as much as 4 degrees C within the next twenty years. These changes to the temperature and moisture regimes during the critical time period have the potential of radically altering the time available for ecosystem growth and carbon accumulation.
Giardina, Christian (USDA-Forest Service, North Central Research Station, Houghton, MI, 49931; Phone: 906-482-6303 Ex 20; Fax: 906-482-6355; Email: cgiardina@fs.fed.us)
Belowground Carbon
Allocation in Forests in Response to Global Change
C.P. Giardina*
Belowground carbon allocation (BCA) in forests regulates soil organic matter formation and influences biotic and abiotic properties of soil such as bulk density, cation exchange capacity, and water holding capacity. On a global scale, the total quantity of carbon allocated belowground by terrestrial plants is enormous, exceeding by an order of magnitude the quantity of carbon emitted to the atmosphere through combustion of fossil fuels. Despite the importance of BCA to the functioning of plant and soil communities, as well as the global carbon budget, controls on BCA are relatively poorly understood. Consequently, our ability to predict how BCA will respond to changes in atmospheric greenhouse gases, climate, nutrient deposition, and plant community composition remains rudimentary. In this synthesis, BCA will be examined from three perspectives: coarse-root standing stock, belowground net primary production (BNPP), and total belowground carbon allocation (TBCA). For each, methodologies and methodological constraints are described. Available data are then used to understand variation in BCA that relates to changes in species composition, mean annual temperature, or elevated CO2 in existing Free Air CO2 Exposure (FACE) experiments.
Gollany, Hero (USDA-ARS,
48037 Tubbs Ranch Roads, Adams, OR, 97810; Phone: 541-278-4410; Fax:
541-278-4372; Email: hero.gollany@oregonstate.edu)
Incorporated Source Carbon and Nitrogen Fertilizer
Influence on Sequestered Carbon and Soluble Silica in a Pacific
H.T. Gollany*, R.R. Allmaras, S.L. Albrecht, S.M. Copeland, C.L. Douglas, Jr.
Long-term experiments are
ideal for evaluating the influence of agricultural practices on soil organic
carbon (SOC) and its interaction with soil constituents. Limited research has
examined influence of organic amendments on SOC and silica (Si) interaction.
The objectives were to: i) determine the effect of residue management and
organic amendments on SOC accretion; and ii) evaluate the influence of organic
amendments on fine organic matter (FOM) distribution and interaction with
soluble Si. A long-term fallow-wheat (Triticum aestivum L.) experiment
with several residue management practices (NB, no burn; SB, spring burn; and
FB, fall burn), three N rates (0, 45, and 90 kg N ha-1), and organic
amendments (NBM, 11.2 t/ha/yr manure; and no burn pea vines, 1.12
t/ha/yr pea vines) was established on a Walla Walla silt loam (coarse-silty,
mixed, superactive, mesic Typic Haploxeroll) in 1931. The experiment is an
ordered block with 2 replications. Soil cores (2-cm depth increments) were used
to measure coarse organic matter, FOM, pH, bulk density, water-soluble C and
water-soluble Si. The SOC storage for the NBM (5.78 kg C m-2)
was 25% higher than FB0(4.62 kg C m -2) at the 0-50 cm
depth. Nitrogen fertilizer application decreased water-soluble Si by 17% while
manure or pea vines application increased water-soluble Si by 10%. Silica
solubilization and movement in response to reduced pH was greater in the
absence of organic amendments. Increased SOC and associated reduction in Si solubilization
suggest that biological SOC sequestration impacts siliceous pan formation and
enhances drainage.
Gollany, Hero (USDA-ARS,
48037 Tubbs Ranch Road, Adams, OR, 97810; Phone: 541-278-4410; Fax:
541-278-4372; Email: hero.gollany@oregonstate.edu)
Predicting Carbon Sequestration in Agricultural Soils with the Carbon Balance Model ‘CQESTR’
R.W. Rickman, H.T. Gollany*, S.L. Albrecht, W.W. Wilhelm, R.F. Follett, C.L. Douglas, Jr.
The prospect of storing carbon in soil, as organic matter, provides an opportunity for agriculture to contribute to the reduction of carbon dioxide in the atmosphere. However, a description of management effects on soil organic matter (SOM) is necessary to assess carbon storage in soil. A mathematical model, CQESTR, has been developed to evaluate the changes in SOM at the field scale. It computes the rate of biological decomposition of crop residue or organic amendments as they convert to SOM. It is a Microsoft Windows based program that was recently modified to include the effects of soil texture and drainage classes on decomposition rate. The program uses Revised Universal Soil Loss Equation (version 1) c-factor files for crop rotation, yield, tillage and weather data. Additional required data include the number and thickness of soil layers, starting organic matter content and bulk density of each layer, and nitrogen content of the organic residues. Residue nitrogen content can be estimated from tables provided in the program if actual analyses are not available. CQESTR provides tabular or graphic trends in residue and soil organic matter content for the duration of any rotation. The program was calibrated using information from 60-year old long-term wheat-fallow rotation experiments conducted near Pendleton, OR and validated with long-term organic matter databases from various parts of North America. However, recent modifications have not been compared with field data. Initial simulations predict that management practices that remove crop biomass or promote microbial decomposition, inversion tillage and fallow, consume existing SOM. Practices that increase contributions to biomass, limit inversion tillage and provide annual root and shoot biomass return to the soil promote carbon storage. Projected trends of SOM content at two sites for the GRACEnet (Greenhouse Gas Reduction through Agricultural Carbon Enhancement network) study are provided for illustration and discussion.
Grace, Peter (Michigan State
University, W.K. Kellogg Biological Station, Hickory Corners, MI, 49060-9516;
Phone: 269-671-2359; Email: gracep@msu.edu)
Maximizing Net Carbon Sequestration in Agroecosystems of the North Central Region
P.R. Grace*, S.H. Gage, M. Colunga-Garcia, G.P. Robertson, G.R. Safir
The identification of high potential regions and management strategies for sequestration of carbon in agroecosystems is an important policy objective in the mitigation of global climate change. Regional and sub-regional assessments on the impact of climate change on terrestrial carbon storage allow us to deal with a greater level of detail and spatial resolution than would be feasible for a continental approach whilst still incorporating large, diverse, and economically important regions. The North Central Region (NCR) of the United States comprises the 12 states of the greater Midwest and is the major producer of corn and soybeans in the country, as well as producing half of the nation’s wheat. The major Land Resource Region in the NCR is the Central Feed Grains and Livestock Region, more commonly known as the Corn Belt. We demonstrate the use of a simple process based simulation model, SOCRATES, within a generic data handling environment, MASIF, to rapidly integrate spatially explicit climate, soil and terrestrial ecosystem characterization data to estimate changes in soil organic carbon and associated greenhouse gas emissions within agricultural soils the NCR in response to management and projected changes in climate over the next century. The main considerations in using SOCRATES is its ability to accurately predict carbon and associated greenhouse gas emissions using non-site specific concepts of carbon cycling and biogeochemistry, its relative ease of use and minimal data input requirements. In its purest form, SOCRATES uses a weekly time step, only requires mean annual precipitation and temperature data, soil clay content or cation exchange capacity. Utilizing extensive non-CO2 emissions data from the Long-Term Ecological Research experiment at the Kellogg Biological Station, we can also provide initial estimates of Global Warming Potential of management strategies across the NCR.
Grandy, A. Stuart (Michigan
State University, W.K. Kellogg Biological Station, 3700 E. Gull Lake Drive,
Hickory Corners, MI, 49060; Phone: 269-671-2336; Email: grandya1@kbs.msu.edu)
Is Carbon Sequestration Following No-till Conversion Associated with Changes in Crop Yields and Nitrogen Cycling?
A.S. Grandy*, T.D. Loecke, G.P. Robertson
Soil carbon sequestration and greenhouse gas abatement in agriculture are two of a limited number of rapidly-deployable, high impact CO2 stabilization options now available to policy makers. No-till cropping generally increases soil C stocks but its deployment has been limited by the perception that accelerated rates of N leaching and immobilization may limit N availability and decrease yields. We studied the effects of no-till conversion on C sequestration and annual patterns of nitrous oxide flux, soil moisture, soil physical properties, and crop yields in a corn-soybean-wheat cropping system in southwestern Michigan. Our measurements were initiated six years after no-till conversion in order to target long-term changes in yields and associated environmental processes and continued for six to eight years. No-till increased organic C concentrations from 0.94 to 1.24 kg m-2 (30.0 g C m-2 y-1) but had little effect on total N2O emissions. Although no-till management modified soil inorganic N concentrations during the growing season (e.g. in 1996 average soil NO3-N concentrations were ca. 16 µg g-1soil in conventional till and 13 µg g-1 in no-till ) average yields of all three rotation crops were unaffected by tillage management suggesting that altered N availability did not limit plant productivity. In 2001, 15 years after conversion, no-till increased soil aggregate mean weight diameter from 1.3 to 2.1 mm but did not significantly alter bulk density to 5 cm. Our results suggest that crop yields potentially remain stable long after no-till conversion and that increased C sequestration and aggregation and decreased global warming potential (GWP) are not necessarily accompanied by meaningful declines in N availability.
Grandy, A. Stuart (Michigan State University, W.K. Kellogg Biological Station, 3700 E, Gull Lake Drive, Hickory Corners, MI, 49060; Phone: 269-671-2336; Email: grandyal@kbs.msu.edu)
Physical and Microbial Controls over Trace Gas Fluxes Following Initial Cultivation
A.S.
Grandy*, T.D. Loecke, G.P. Robertson
Tillage reduction can contribute to soil carbon sequestration and greenhouse gas abatement in agriculture by slowing the turnover of organic C and N. An unanswered question, however, regards the stability of stored C and N following subsequent tillage of soils at maximum soil organic matter equilibrium. We investigated the responses of CO2 and N2O fluxes, nitrifier and denitrifier enzyme dynamics, and soil C and N pools for two years immediately following initial cultivation of a previously uncultivated midsuccessional community in Southwest Michigan. Carbon dioxide fluxes increased immediately after cultivation and remained at levels greater than 150% of those in reference sites. Increased CO2 fluxes were associated with the release of particulate organic matter from protected anaerobic microsites within aggregates, which declined between 30 and 50%. Nitrous oxide fluxes increased from an average of about 0.8 to 3 g N2O-N ha-1 d-1 following cultivation and were related to substantial soil nitrate increases. The distribution and activity of nitrifier and denitrifier enzymes were additionally altered by cultivation and may indicate a microbial-level control over trace gas flux changes. These results suggest that soil carbon and nitrogen change following the onset of cultivation are faster than commonly assumed and suggest further that recently sequestered soil carbon may be at significant risk for loss upon the resumption of tillage or other soil disturbance.
Halvorson, Ardell (USDA-ARS, Centre Ave, Bldg. D, Ste 100, Ft. Collins, CO, 80526; Phone: 970-492-7230; Fax: 970-492-7213; Email: ardell.halvorson@ars.usda.gov)
Tillage and Nitrogen Effects on Soil Carbon and Greenhouse Gas Emissions Under Irrigated Continuous Corn
A.D. Halvorson*, A.R. Mosier, C.A. Reule, X.J. Liu
Tillage system and N fertilization effects on soil organic C (SOC) sequestration and greenhouse gas emissions in irrigated continuous corn production are not well documented. A study was initiated in 1999 to investigate the potential of no-till (NT) management to sequester SOC while maintaining continuous corn yields at levels similar to conventional-till (CT) practices. In April 2002, measurement of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes from three of the N rates (0, 134, and 224 kg N/ha) were initiated in the NT and CT systems. Fluxes of CO2, CH4, and N2O were measured, using vented chambers, one to three times per week, year round, from April 2002 through October 2004. CH4 fluxes were small and did not differ between tillage treatments, but varied with year. CO2 efflux was higher in CT compared to NT in 2002, but was not different by tillage treatment in 2003 and 2004. N2O fluxes increased linearly with increasing N-fertilizer rate each year with emission rates varying with year but not by tillage treatment. Trends were for SOC to be increasing in the NT system but remaining fairly constant in the CT system. Grain yields and crop residue increased with increasing N rate in both tillage systems, but grain yields were slightly higher in CT than in NT system. NT soils were greater net sinks for global warming potential when adequate fertilizer was added to maintain crop production than CT soils. The results suggest that economic viability and environmental conservation can be achieved by minimizing tillage and utilizing appropriate levels of fertilizer
Ham, Jay (Kansas State
University, Dept. of Agronomy, Throckmorton Hall, Manhattan, KS, 66506; Phone:
785-532-6119; Email: jayham@ksu.edu)
Automated Chambers for Measuring Soil and Canopy Respiration From Rangeland
J.M. Ham*, E.J. Benson, F.W. Caldwell, C.E. Owensby
A multiplexed automated chamber system was developed to monitor ecosystem respiration (R) from tallgrass prairie near Manhattan, Kansas. Chambers were deployed for one year in the source areas of eddy covariance towers in grazed and ungrazed pastures. The main purpose of the chambers was to improve long-term estimates of nocturnal and dormant season CO2 losses. Chamber data were used to evaluate the performance of the eddy covariance systems at night when tower-based net carbon exchange measurements should be equal to R. Rectangular opaque chambers (0.85 m x 0.85 m x 0.25 m) were automatically deployed at 1 or 2 hourly intervals using four-arm linkage and 12V-winch. Flux was determined from CO2 vs. time curves using a non-steady-state measurement. When idle, the chambers rested on a parking platform north of the sample plot; thus, the plot microclimate was not affected. Surface fluxes followed strong diurnal patterns that were correlated with air temperature. Predawn fluxes were often 45% less than daytime maximums. During June 2004, the peak of the growing season, daily CO2 fluxes were 33.6 and 28.9 g/m2/d from the ungrazed and grazed plots, respectively. Grazing caused a 12 to 16% reduction in respiration. Results also will address the best ways to calculate chamber-based fluxes from the CO2 vs. time curves and (2) optimal methods for sampling gap filling.
Hamilton, Stephen (Michigan State University, Kellogg Biological Station, 3700 E. Gull Lake Drive, Hickory Corners, MI, 49060; Phone: 269-671-2231; Fax: 269/671-2104; Email: hamilton@kbs.msu.edu)
The Fate of Agricultural “Lime” Amendments: Implications for Terrestrial Carbon Sequestration
S.K. Hamilton*, G.P. Robertson, A.L. Kurzman
A foundation of intensive agriculture in humid regions is the periodic addition of lime, usually carbonate minerals, to neutralize acidity that would otherwise render soils infertile. Agricultural lime use is a massive anthropogenic flux of carbon that is amenable to management. A whole-system global warming potential (GWP) analysis of agricultural systems by Robertson et al. (2000; Science 289: 1922) showed agricultural liming to be the second most important source of GWP in conventional annual crop systems (after nitrous oxide release), under the assumption that inorganic carbon in these minerals eventually becomes a source of carbon dioxide as the lime is consumed. Current IPCC guidelines follow that assumption as well. However, that is not necessarily true because it depends on the weathering reactions, which in turn are pH-dependent. At pH >5, most of the dissolution of carbonate minerals can be ascribed to carbonic acid weathering, which acts as a sink for soil carbon dioxide because for every mole of lime-derived C that dissolves, 2 moles of bicarbonate ion are produced. If the lime or bicarbonate ions derived from it come into contact with a strong mineral acid, carbon dioxide will be produced, creating a carbon dioxide source. Measurements of the ionic composition of soil solutions from beneath various row crops and natural vegetation in Michigan, together with analysis of tile-field drainage and small streams in agricultural areas of Michigan, Illinois, and Iowa, reveal the variable fate of carbon added as lime. The agricultural soils, to which dolomitic lime was added, span the range from nearly complete conversion of the lime carbon to free carbon dioxide to sequestration of additional carbon dioxide in an amount nearly equivalent to the lime carbon that has dissolved. Drainage waters from diverse agricultural fields show a similar range. Differences among agricultural soils in the fate of the carbon in lime are likely explained primarily by the variable importance of acidifying reactions, and particularly by differences in rates of nitrification associated with fertilization or nitrogen fixation. An increase in the availability of lime in the soil will shift the net carbon balance associated with liming from a carbon dioxide source to a carbon dioxide sink, as will a decrease in acidifying reactions. If we can learn the circumstances under which one reaction pathway dominates the other in these soils, and if these circumstances could be manipulated (by, for example, inhibiting nitrifying bacteria or adjusting the source, amount, or placement of nitrogen fertilizers), then we could explore new management options for sequestering inorganic carbon in agricultural soils and underlying aquifers.
Hao, Xinmei (Michigan State University, Dept. of Crop and Soil Sciences, East Lansing, MI, 48823; Phone: 517-3550271-245; Email: haox@msu.edu)
Sensitivity of the CENTURY Model in Predicting Change of Soil Carbon with Different Agricultural Practices
A. Kravchenko, X. Hao*
The CENTURY model has been widely applied to predict change of soil organic matter in agricultural systems. We studied the sensitivity of the CENTURY model to several factors, including soil texture, size of soil carbon pools, precipitation, and temperature. Four management practices, differing in tillage and fertilizer input, were applied. Then statistic method was used to study the interrelationships among these factors.
Harris, Ronny (Los Alamos National Laboratory, Earth and Environmental Sciences Division, Los Alamos, NM, 87545; Phone: 505-665-9773; Fax: 505-667-7460; Email: rdharris@lanl.gov)
Measuring Total Carbon And Nitrogen In Soils Using Laser-Induced Breakdown Spectroscopy (LIBS)
R.D. Harris*, M.H. Ebinger, C.W. Meyer, R.J. Gehl
Laser-induced breakdown spectroscopy (LIBS) has been used to measure a variety of elements in soil such as carbon, nitrogen, potassium, sulfur and phosphorus. Recent technological advances have enabled soil carbon distribution measurements to be conducted at 1 mm intervals from intact soil cores. This new application preserves information on the spatial variation of soil carbon in heterogeneous soils. The high resolution data provide new ways to estimate carbon inventories while decreasing costs. The ability to measure nitrogen in soil is also important for maintaining soil quality and maximizing productivity. Quantification of soil nitrogen with LIBS is complicated by the fact that ambient air is 78% nitrogen. This problem can be solved by performing the analysis in a partial vacuum or by using an argon purge.
Hatfield, Jerry (USDA-ARS Ames, Iowa, National Soil Tilth Laboratory, 2150 Pammel Drive, Ames, IA, 50011; Phone: 515-294-5723; Fax: 515-294-8125; Email: hatfield@nstl.gov)
Spatial Variation of Carbon Dioxide and Energy Balance
Fluxes among Corn and Soybean Fields in
J.L. Hatfield*, J.H. Prueger, W.P. Kustas
Estimates of fluxes from cropped surfaces are generally conducted in fields that are assumed to be under uniform management and similar soil types. There is little information available on the spatial or temporal variation of carbon dioxide or energy balance fluxes across production-sized fields of corn (Zea mays L.) or soybean (Glycine max (L.) Merr.). This study was conducted in 2002 as part of a larger scale experiment on surface energy balances across central Iowa. Twelve eddy covariance/energy balance stations (6 in corn, 6 in soybean) included measurements of water vapor, carbon dioxide, sensible heat, net radiation and soil heat fluxes, air temperature, surface temperature, wind speed and precipitation. The stations were placed in the fields shortly after planting and remained until near harvest. Diurnal variations in CO2 and H2O vapor fluxes revealed that the magnitude of the fluxes is large and that variation of the fluxes among fields was consistent throughout the season. Integration of the daily fluxes into seasonal totals showed considerable differences among crops and fields. Flux differences were the result of the effect of varying soil types on water holding capacity. Seasonal integrated values were lower than estimates derived from biomass samples collected within the fields and the measurement of the C content of the biomass. Understanding patterns of spatial variability of carbon dioxide and energy balance fluxes enhances our ability to characterize regional scale fluxes.
Heath, Linda (USDA-Forest Service, PO Box 640, Durham, NH, 03824; Phone: 603-868-7612; Fax: 603-868-7604; Lheath@fs.fed.us)
Annualized Forest Carbon
Estimates for U.S. National Greenhouse Gas Reporting
L.S. Heath*, J.E. Smith
With the ratification of the United Nations Framework Convention on Climate Change in the 1990’s, like many nations, the United States agreed to develop and make available a national inventory of sources and sinks of all greenhouse gases not controlled by the Montreal Process. The U.S. Environmental Protection Agency (EPA) prepares this inventory. We describe methods used to calculate the annual forest carbon stocks and stock changes used in the 2005 inventory, and present results. Reported results begin in 1990. This method also produces consistent estimates at the state- and regional-level. Our estimates are based on surveys conducted on forests of the U.S. by the USDA Forest Service, Forest Inventory and Analysis (FIA) Program. The surveys are conducted by state, using remote sensing to determine forest area, and field measurements traditionally focused on merchantable timber volumes. We developed a number of techniques to augment the data to estimate carbon stocks. Carbon stock changes are calculated by subtracting consecutive carbon stocks. Discontinuities in past surveys, incomplete data, and changes in evolving survey protocols contribute to complications to this approach. We discuss methods used to overcome these issues. To annualize the data, we assigned carbon stocks to the year data was collected by state and occasionally by owner, using basic interpolation. Results indicate that forests in the coterminous US are sequestering 163 Tg C per year, not including carbon removed from the forest by harvesting.
Heaton, Emily (University of Illinois, 1201 W. Gregory Drive, 379 Madigan Lab., Urbana, IL, 61801; Phone: 217 244-6317; Email: ecaveny@uiuc.edu)
Miscanthus: Climate Change
Mitigation Potential of a High Yielding Energy Crop in
E.A. Heaton*, T.B. Voigt, S.P. Long
Energy crops can provide an economical, renewable energy source and a profitable alternative to surplus grain crops. US researchers have focused on switchgrass (Panicum virgatum) as a means to this end, while European investigators have concentrated on Miscanthus (Miscanthus x giganteus). To date, side-by-side comparisons of mature stands (established at least 3 years) of these crops have not been reported in the peer-reviewed literature. We examined all peer-reviewed articles describing productivity of these species and extracted dry matter yields, nitrogen fertilization (N) and precipitation/irrigation data. Statistical analysis revealed that the species differ in their response to water and N. Miscanthus yields averaged 22 Mg/ha (97 observations) compared to average switchgrass yields of 10 Mg/ha (77 observations). The first field trials of Miscanthus and switchgrass in the U.S. were planted in Illinois in June 2002. Here we report that 2nd year yields have already reached the average yields in the literature review. Both crops reached maximum biomass in August with yields of 22.55 Mg/ha and 12.55 Mg/ha for Miscanthus and switchgrass, respectively. By winter, when energy crops are often harvested, Miscanthus yields had decreased to 19.30 Mg/ha and switchgrass yields to 8.40 Mg/ha, representing a 14% and 33% loss in biomass, respectively.
Hom, John L. (USDA-Forest Service, Northeastern Research Station, 11
Campus Blvd., Ste 200, Newtown Square, PA, 19087; Phone: 610-557-4097; Fax:
610-557-4095; Email: jhom@fs.fed.us)
Studies on Carbon Dioxide Concentration and Carbon Flux in
a Forested Region in Suburban
J. Hom*, M. Patterson, S. Grimmond,
B. Crawford, Q. Holifield, I. Yesilonis,
D. Golub,
B. Offerle , D.
Nowak, G. Heisler, R. Pouyat,
W. Zipperer
The purpose of this
study is to characterize carbon dioxide concentrations and the carbon fluxes
from a highly vegetated residential area of Baltimore, and to provide annual estimates of carbon
sequestration for this forested suburban ecosystem. The Cub Hill site
is located 14 km from the Baltimore city center. It is the first permanent
urban carbon flux tower to measure carbon flux in an urban/suburban
environment. The site is in a yellow
poplar-oak-hickory stand with a canopy height of 65-80 feet. Immediately south
is a residential area, and large areas of forest and vegetation are to the
north and west. The ten level profile system for CO2 and H2O concentration was initiated in
2001. An eddy correlation system for
carbon, water, and energy fluxes was added later.
The average
concentration in this Baltimore suburban environment is slightly higher than
the global background, averaging 385 ppm at the top
of the Cub Hill tower. Monitoring stations in Baltimore city center, where
there is less tree cover and more automobile traffic, is much higher -
averaging 511 ppm.
The influence of the workweek showed a weekly
cycle with lower overall CO2 emissions for the weekends than
that of the weekdays during the winter, possibly due to higher energy use for
the workweek. However, this was less obvious in the spring and summer with the
influence of the deciduous vegetation.
Metropolitan areas
have an average tree cover of 33.4 percent (urban counties) and support 25
percent of the USA’s total tree canopy cover.
Estimates of suburban forest area and the amount of carbon stored are
not well known, as they fall between the inventories of rural and urban
forests. This study will improve our
understanding for carbon flux and carbon sequestration in areas traditionally
classified as non-forest lands.
Hoover, Coeli (USDA-Forest Service, Forestry Sciences Lab, PO Box 640, Durham, NH, 03824; Phone: 603-749-1477; Email: choover@fs.fed.us)
Thinning and Carbon Sequestration in Allegheny Hardwoods: Results from One Thinning Cycle
C.M. Hoover*
Ongoing climate change negotiations have focused attention on the role of forests in the global carbon cycle; this role is also important in international sustainability agreements such as the Montreal Process. Consequently, understanding the effects of management on forest carbon cycles is a high priority. Thinning forest stands is a commonly employed silvicultural technique that is used to achieve a variety of objectives: concentrating resources on selected stems, improving stand structure, and improving species composition, among others. This analysis uses data from one thinning cycle of a large study in Northwestern PA. Fourteen plots in five blocks of the study were used: seven unthinned control plots, and seven plots thinned to 60% relative density. Twelve plots were in the Allegheny hardwood forest type (cherry-maple), while two plots were in stands dominated by sugar maple. Age at thinning ranged from 50-80 years since establishment; all plots are located in even aged stands. Different blocks of the study were established in different years; this study presents the results from the first fifteen years since thinning in each block, regardless of date of establishment. Carbon stocks were estimated for each five year period for the following pools: aboveground biomass of woody stems (greater than 2.5 cm dbh), coarse root biomass, dead aboveground biomass, logging slash, and products. From the carbon stock estimates, average annual change over the fifteen year study period was also computed for each stand. Carbon stocks in thinned plots were less variable across study blocks than carbon in control plots and less biomass was lost to mortality in thinned plots, indicating that the treatments were achieving their primary objectives. All plots had positive values for average annual change in carbon stocks, demonstrating that carbon was sequestered. However, the average increase in carbon stocks was lower in thinned stands than control stands, indicating lower carbon sequestration rates. The plots will continue to be inventoried as stand age increases and the second thinning cycle is entered, providing a more detailed picture of the effects of thinning treatments on carbon sequestration in Allegheny hardwood stands.
Huggins, David (USDA-ARS, 215 Johnson Hall, Washington State University, Pullman, WA, 99164; Phone: 509-335-3379; Fax: 509-335-3842; Email: dhuggins@wsu.edu)
Tillage and Corn-Soybean Sequence Effects on Carbon Dynamics Estimated from Natural C-13 Abundance
D.R. Huggins*, R.R. Allmaras, C.E. Clapp, J.A. Lamb
Tillage and crop rotation are
major regulators of soil organic carbon (SOC).
Our objectives were to assess tillage and crop sequence effects on SOC
storage and dynamics using natural 13C abundance. A randomized, split-plot design (four
replications) with main plots consisting of tillage treatment: moldboard plow
(MP), chisel plow (CP) and no-tillage (NT) and subplots of crop sequence:
continuous corn (CC), continuous soybean (SS) and alternating corn-soybean (CS)
was established in 1981. Soil samples
were collected in each treatment after 14 years and analyzed for bulk density,
pH, delta 13C values and SOC.
Crop sequence effects on total SOC (0 to 45 cm) occurred in CP and
NT. The CP treatment had 20% greater SOC
in CC than SS, while NT had 15% greater SOC in CC than SS. Tillage effects on SOC were greatest in CC
where CP had 30% and NT 20% more SOC than MP.
Continuous soybean was the only crop sequence where tillage had no
influence on SOC. Interaction between
tillage and crop sequence on SOC resulted in CP treatments with corn and NT
continuous corn to have the most SOC (averaging 165 Mg ha-1), while
all MP and SS treatments and NT treatments with soybean, the least SOC
(averaging 137 Mg ha-1).
These results underscore the importance of both crop sequence and
tillage in controlling SOC storage and dynamics.
Huggins, David (USDA-ARS, 215
Johnson Hall, Washington State University, Pullman, WA, 99164; Phone:
509-335-3379; Fax: 509-335-3842; Email: dhuggins@wsu.edu)
D.R. Huggins*, R.E. Rossi, A.R. Kemanian, W.L. Pan
Improving N use efficiency has been identified as the primary agricultural means for decreasing nitrous oxide emissions. Quantifying field-scale variability in nitrogen use efficiency (NUE) is essential for developing management strategies that increase NUE. Our objectives were to assess field-scale variation in hard red spring wheat (HRS) NUE, yield-protein relationships and unit N requirements; and to evaluate the crop physiologic and environmental suitability of HRS production. Data from two plot-scale studies with tillage and N rate treatments were combined with one field-scale (13 ha) study to evaluate HRS performance. Measurements of grain yield, grain N, aboveground plant N, applied N, and pre- and post-harvest root-zone soil N were used to assess components of NUE including N retention, uptake and utilization efficiency. Plot-scale HRS data displayed characteristic yield-protein relations with increasing N supply and expressed a curvilinear relationship between NUE and grain protein concentration (GPC). Field application of plot-derived unit N requirements gave highly variable within-field responses of grain yield (1.3 to 3.8 Mg ha-1), GPC (106 to 179 g kg-1) and N uptake efficiency (12 to 48%). We concluded that: (1) N requirements and management strategies based on small-scale plot data cannot be extrapolated to more diverse field-scale conditions; (2) uniform field-scale applications of N are not likely to achieve field-scale goals of grain yield, GPC and NUE; (3) a large proportion of the field may not be suitable for HRS production unless site-specific N management strategies that improve NUE are devised; (4) NUE components and indices can be used to evaluate crop grain yield-GPC relations and to diagnose field areas with over or under application of N, poor N utilization or uptake efficiencies, and areas with significant N loss; and (5) devising N requirements and management strategies for HRS should use a combination of plot- and field-scale data.
Hunt, E. Raymond (USDA-ARS,
Hydrology and Remote Sensing, Beltsville, MD, 20705; Phone: 301-504-5278; Fax:
301-504-8931; Email: erhunt@hydrolab.arsusda.gov)
Simulation of Erosion and Soil Carbon Sequestration Over
an Agricultural Landscape in
E.R. Hunt*, P.C. Doraiswamy, C.S.T. Daughtry, G.W. McCarty, J.L. Hatfield, R.C. Izaurralde
Agricultural soils can be a source or a sink of CO2
depending on management. The impacts of
erosion depend on topography, hence landscape position affects the amount of
soil carbon sequestration. We used a
site in central Iowa (50 km by 100 km, 41.69460 to 42.73230 N and 93.84160 to 93.16100 W), which was the site of the
Soil Moisture Experiment 2002. The soils
are recently derived from calcareous glacial tills from the Des Moine Lobe
landform, and are dominated by the fine-loamy Clarion-Nicollet-Canisteo series,
which are dependent on landscape position.
This study examines the interaction of landscape and management on soil
carbon sesquestration. The EPIC-CENTURY biogeochemical model was used to
simulate the baseline level of soil carbon from soil survey data and project
changes in soil organic carbon (SOC) under different tillage practices for corn
and soybean crops. Areas that were not
agriculture (cities, towns and lakes) were masked out for the computer
simulations. There were two periods of
model simulations. First, a 26-year period (1970-1995) was simulated using
conventional tillage practices. Fertilizer inputs used the state-wide average
as recorded by the USDA NASS. Actual
weather data from NOAA NWS were used to drive the model. Initial SOC were obtained from the average
soil organic matter concentration and average soil bulk density from the
STATSGO and SSURGO geographic databases.
Then, four different modeling scenarios were applied to the region for
the next 25 years (1996-2020): A, conventional tillage; B, mulch tillage; C,
no-till method; and D, no-till with a rye cover crop. Weather data were generated by the model
using statistics from the climate record (1970 to 2000); the same weather file
was used for each simulation. After 26
years of conventional tillage in a two-year maize-soybean rotation, the average
carbon content was 60 Mg C/ha, which is a reduction of 22 Mg C/ha from the
initial conditions. In 2020, conventional tillage is predicted to reduce the
average SOC another 10 Mg C/ha to establish an expected baseline. With erosion
turned off in the model, simulated SOC in 2020 under continuous conventional
tillage was 27% higher than the baseline. SOC simulated using mulch till is 59
Mg C/ha in 2020, which is not significantly different from the starting
conditions in 1995. However, when compared to the expected baseline loss of
carbon over time, mulch till sequestered 9 Mg/ha of carbon in the simulations,
which is 300 kg C ha-1year-1.
No-tillage practices with and without a winter cover crop averaged 76
and 78 Mg C/ha, respectively, which represents an absolute gain in soil carbon
over the 1996-2020 time period, almost up to the original amounts in the
STATSGO and SSURGO databases. The extra operations of planting the winter cover
crop is the reason for the EPIC-Century model predicting slightly lower carbon
gain. The amount of soil carbon sequestered in these simulations is from both
increased inputs of residue and reduced loses from erosion. The residue amount on
the ground can be determined using remote sensing, which will show the overall
change and type of conservation tillage practices adopted by farmers. A more
important fact is that the location of these practices has a strong interaction
with other landscape variables, such as erosion, so area-wide averages will not
give a reliable indication on the yearly rate of carbon sequestration.
Ideris, Alan J. (Atmospheric Science, University of California-Davis, One Shields Ave., Davis, CA, 95616; Phone: 530-752-1868; Fax: 530-752-1793; Email: ajideris@ucdavis.edu)
Pressure Pumping
Effects on Soil Efflux Measurements of CO2
A.J. Ideris*, K. T. Paw U, J. Kochendorfer, L. Xu
Carbon dioxide is the major trace gas responsible for predicted global climate change. Anthropogenic CO2 is believed to be the major constituent to the steady rise in the mean CO2, which has been rising more rapidly than the biometeorological system has experienced in recent geological history. The approach of measuring the soil CO2 efflux due to pressure pumping will give us a better understanding of the soil-atmosphere interfacial, which will consequently allow for better development of instrumentation, measurement techniques, and adequate theoretical equations. In our study, we measured the barometric pressure (10 Hz) at depths of 40 cm, 20 cm, 10 cm, and the surface by use of fast response pressure transducers, and examined a possible relationship with the amount of soil CO2 efflux from the total net ecosystem exchange. The soil CO2 efflux was measured by use of an eddy-covariance system composed of a sonic anemometer and Licor-7500 infrared CO2 and H2O gas analyzer. In addition, coefficients for pressure attenuation with depth have been determined. We report on the relationship between pressure measurements and soil CO2 efflux, which could have several implications. Such implications include improving measurement techniques and instrumentation by accounting for some of the errors associated with using soil chambers to measure CO2 efflux.
Islam, K. Rafik. (The Ohio
State University, 1864 Shyville Road, Piketon, OH, 45661; Phone: 740-289-2071;
Fax: 740-289-4591; Email: islam.27@osu.edu)
Biological, Chemical and Physical Sequestration of Soil Carbon in Response to Tillage
K.R. Islam*, A. Sundermeier
Increasing soil carbon
sequestration through conservation management practices can improve
environmental quality. To evaluate the impact of no-till (NT) continuous corn
system on carbon sequestration, composite soil core samples at 0-7.5, 7.5-15,
15-22.5 and 22.5-30 cm depth were collected from 2, 8, and 40 yr no-till and
their adjoining conventionally-tilled (CT) replicated plots at the Northwest
Branch of the Ohio Agricultural Research and Development Center in Wood County,
Ohio in fall of 2004. The soil at the experimental location is Hoytville clay
loam (Fine, illitic, mesic Mollic Epiaqualfs), which is a deep very poorly
drained soil with moderately slow permeability. Soil samples were processed and
analyzed for concentration and masses of biologically (e.g. microbial biomass
and active C), chemically (e.g. passive, extractable, and total organic C) and
physically defined (e.g. particulate organic C) C pools and basic soil
properties. The concentration and mass of microbial biomass, active,
extractable, particulate and total organic carbon pools increased significantly
in NT soil over time compared to CT soil. Temporal effect tillage had more
pronounced on active, microbial biomass and particulate organic carbon than
total organic content. Variations in C pools under different tillage systems
were more pronounced at surface depth (0-7.5 cm) of soil. Combined over depth
0-30 cm, the profile wise storage of microbial biomass, active, particulate and
total organic C pools varied significantly in response to the length of NT
operation. Among the C pools, microbial biomass and active C changed
consistently in response to tillage operations. Significantly greater
concentration and mass of various C pools in NT soils compared to CT soils are
possibly due to surface deposition of crop residues, less disturbance, greater
physical protection over time.
Islam, K. Rafik. (The Ohio State University, 1864 Shyville Road, Piketon, OH, 45661; Phone: 740-289-2071; Fax: 740-289-4591; Email: islam.27@osu.edu)
Sequestration of Soil Carbon on Ohio Mine Sites After Reclamation and Reforestation
D.K. Apsley*, K.R. Islam, P.S. Perry
US agricultural soils and forests sequester about 700 million tones of CO2 equivalent per year (EPA 2004), over 90% of which is from forest carbon sequestration. Although this amount alone only offsets about one tenth of national greenhouse gas emissions, various actions can be taken to enhance carbon sequestration in forest soils especially mine sites. To evaluate the impact of reforestation activities on carbon sequestration in degraded lands, soil core samples at 0-15 cm depth were collected from various reclaimed striped mine sites and an unreclaimed spoil site within the Wayne National Forest, Ohio. Soil samples were composited, processed and analyzed for concentration and masses of active, passive, extractable, organic, inorganic and total C pools. Averaged across forest species, the concentration and mass of active, organic and total carbon pools were significantly higher in reclaimed strip mined soil than unreclaimed mine spoil. Reclaimed mine soils under white (Pinus strobus) and Virginia pine (P. virginiana) sequestered more carbon than mixed stands of Virginia pine and hardwood species, and mixed hardwood species, respectively. Carbon sequestration was more pronounced in the active fraction of soil organic matter. Reclaimed striped mine soils under Virginia and white pine sequestered 35% more active carbon content within the first 10 to 18 years following reclamation than unreclaimed mine spoil under native stands of hardwood species after 30 years. Likewise, reclaimed mine soils under Virginia and white pine sequestered 30% more total organic carbon than in unreclaimed spoil over the same time periods.
Izaurralde, R. Cesar (Joint
Global Change Research Institute, 8400 Baltimore Ave., Suite 201, College Park,
MD, 20740; Phone: 301-314-6751; Fax: 301-314 –6760;
Email: cesar.izaurralde@pnl.gov)
Modeling Long-Term Soil Organic Carbon Dynamics as Affected by Management and Water Erosion
R.C. Izaurralde*, W.M. Post, J.R. Williams, P. Puget, A.M. Thomson, W.B. McGill, R.Lal, L.B.Owens
The soil C balance is determined by the difference between inputs (e.g. litter, crop residues, decaying roots, organic amendments, depositional C) and outputs (e.g. soil respiration, dissolved organic C leaching and eroded C). Two competing hypotheses suggest erosion may either increase or decrease output. One hypothesis states that C from eroded fields becomes “sequestered” in depressional areas and thus is rendered unavailable for decomposition. An alternative hypothesis argues that due to aggregate breakdown during erosion events, physically-protected C becomes accessible, thereby increasing oxidation of C and emission of CO2. The objectives of this paper are to: (a) review literature to determine the extent to which empirical evidence supports either the sequestration or increased accessibility hypothesis in managed ecosystems, and (b) present modeling results of two 60-year experiments documenting changes in soil C as affected by management and water erosion. The treatments were established in 1939 on two ~1 ha watersheds (W128 and W188) at the USDA North Appalachian Experimental Watershed facility north of Coshocton, OH. Soils in these watersheds were developed from loess-like deposits over residual bedrock and are silt loam in texture. Soil and crop management changed over time in both watersheds. Until the early 1970s both watersheds were under a corn-wheat-meadow-meadow rotation. Watershed 128 has been under continuous plow till corn since 1984. Watershed 188 has been under continuous no till corn since 1970. The EPIC model (v. 3060) was used for the simulations. It is capable of simulating wind and water erosion and contains subroutines to simulate C and N dynamics. Simulated C stocks were lower than observed values but reproduced the trend of higher soil C content under no till management. Eroded C under no till (W188) was about one fourth that under plow till (W128). The annual simulated rates of C erosion under plow till was 0.333 Mg C ha-1 y-1 while under no till it was 0.084 Mg C ha-1y-1. These rates were higher than those estimated with 137Cs (0.041 Mg C ha-1 y-1) and measured with sediment collectors (0.026 Mg C ha-1 y-1) in a nearby watershed. It is possible that some of the discrepancy between predicted erosion and sediment collected may be explained by the occurrence of soil deposition within the watershed. These results clearly demonstrate the significance of C erosion on the C balance. However, they do not answer directly either of the two hypotheses. Further research using landscape models will be conducted to elucidate the effects of depositional C on the C balance.
Jachowski, Kathleen (Solutions, 217 Road 6EH, Cody, WY, 82414; Phone: 307-587-3723; Email: solution@180com.net)
K. Jachowski*
The Wyoming Legislature passed legislation in 2001 establishing the Wyoming Carbon Sequestration Advisory Committee. The responsibilities of the advisory committee are to: a) recommend policies or programs to encourage Wyoming agricultural and forest landowners to participate in developed C trading programs, b) encourage production of educational materials and organize outreach workshops/conferences about C sequestration, c) identify and recommend areas of research needed to understand and quantify C sequestration on agricultural and forest lands, and d) advise and assist the Director of the Department of Agriculture in the preparation of technical reports on the subject. The legislation mandated the committee be comprised of the following entities: Director of the Department of Agriculture, Director of the Department of Environmental Quality, livestock producer, crop producer, private forest landowner, forest products manufacturer, conservation districts, transportation industry, USDA-Agricultural Research Service, USDA-Natural Resources Conservation Service, oil and gas industry, ethanol industry, College of Agriculture at University of Wyoming, and the electrical generation industry. The Advisory Committee is seeking resources to employ a program coordinator, has established rangeland and forestry research/demonstration studies for educational outreach as well as to improve quantification of potential carbon sequestration rates, and held a C sequestration outreach workshop. In addition, the Advisory Committee is partnering with other states in the development of grant proposals for regional programs related to C sequestration. A 5-year work plan has been developed outlining the vision and scope of work by the committee and identifies research/demonstration projects, workshops/conferences and other educational outreach efforts planned to educate the citizens of Wyoming on the subject of C sequestration and mitigation of global climate change, development of a best management practices guide for C sequestration, and develop an economic assessment of C sequestration potential for Wyoming.
Jacob, James (Rubber Research
Institute of India, Rubber Board, Kottayam, Kerala, 686009, India; Phone:
91-481-235-3311; Email: pappan@scientist.com)
Implications of the Clean Development Mechanism (CDM) to Indian Forestry and Commercial Plantations
J. Jacob*
With the 10th Conference of Parties to United Nations
Framework Convention on Climate Change (UNFCCC) adopting the modalities and
procedures for operationalising Clean Development Mechanism (CDM) under the
Land Use, Land Use Change and Forestry (LULUCF) activities such as
afforestation/reforestation, sink projects such as commercial plantations are
now included under the CDM. This article briefly reviews the history of
international climate change negotiations and the current status of the Kyoto
Protocol with special focus on CDM-Sink projects under LULUCF. The article is
organized into four sections. The first
part briefly discusses the science behind global climate change that convinced
the international political community to enter into serious negotiations that
lead to the genesis of the UNFCCC and the evolution of the Kyoto Protocol. The
politics of climate change negotiations, the US withdrawal from the Kyoto
mechanism, the recent Russian ratification of the Protocol and its timing to
coincide with the US Presidential election are discussed in the second section.
The three market mechanisms established under the Kyoto Protocol to help the
Annex I countries meet their Kyoto targets cost effectively are discussed in
the third section. The clean development mechanism (CDM) is one of the three
market mechanisms established under the Protocol and this has potential
benefits for the developing and the least developed countries. Through this, an
Annex I country can invest in a non Annex I country in a climate-friendly
project that is in tune with the sustainable developmental needs of the host
country and in return obtain certified emission reduction (CER) credits for the
amounts of GHGs that have been prevented from emitted into the atmosphere or
sequestered from the atmosphere as a result of the project. The CERs can be
used in part by the investing Annex I country to offset its QELRCs compliance
under the Kyoto Protocol. Thus CDM is an innovative mechanism addressing GHG
concentrations in the atmosphere through the marketplace. In the last section, the implications of the
CDM for the Indian forestry and commercial plantation sectors are discussed in
the light of the decision taken at the ninth Conference of Parties to UNFCCC
held at Milan during 2003 to include afforestation and reforestation activities
under the CDM and adoption of the modalities and procedures for
afforestation/reforestation projects at CoP 10 at Buenos Aires. Apart from the
carbon sequestered in the biomass, there are several activities associated with
the forestry/plantation sectors that result in a reduction in GHG emission and
hence qualify for CDM investment. These include production of biogas from
processing effluents from plantations like coffee, rubber etc., use of rubber
seed oil as bio-diesel, use of biomass gasifiers and solar thermal system for
drying forestry and plantation produces, technology innovations that improve
the energy use efficiency at any stage of a product manufacturing etc. Growing
energy plantations in the wastelands of the country for the purpose of
generating energy through biomass gasification is a particularly
climate-friendly technology that is eligible for CDM funding. Using species
that have a high carbon sequestration rate and water use efficiency for growing
energy plantations for rural energy needs has great social, economic and
environmental significance in a country like ours that has vast areas of
wastelands available in the remote and rural areas where people do not have
access to adequate and steady supply of energy.
Jagadamma,
Sindhu (Department of Soil Science, School of Natural
Resources, 210 Kottman Hall, The Ohio State
University, 2021 Coffey Road, Columbus, Ohio, 43210; Phone: 614-291-8902
(Res.); Fax: 614 -292-7432; Email: jagadamma.1@osu.edu)
Nitrogen
Fertilization and Cover Cropping Impacts on Soil Carbon Sequestration on a Silt
Loam Soil in West
Soil
carbon sequestration, important to enhancing soil quality and mitigating the climate
change, depends on the amount of crop residue returned to the soil and the
attendant soil and crop management practices. Nitrogen (N) management plays an
important role in soil carbon dynamics. Thus, this study was conducted with the
objective of evaluating the effect of N fertilizer application and cover
cropping on soil organic carbon (SOC) pool and other properties, which affects
soil quality. Replicated soil samples were collected from a long-term
experiment (20 years) at the North Western Experimental Center, Monmouth,
Illinois. The experimental design is split-split plot within a randomized
complete block and the soil type is Mascatine silt loam. There were three main
plot treatments: continuous corn (Zea mays), and two rotation plots with
corn and soybean (Glycine max) grown in alternate years. These main
plots were divided into two subplots: with and without oats (Avena sativa)
grown as cover crops. The split-split plot treatments were five N rates (0 (N0),
70 (N1), 140 (N2), 210 (N3) and 280 (N4)
kg N ha-1). Core samples were collected from each plot up to 90 cm
depth and analyzed for total C, total N, bulk density, aggregate stability,
soil texture and pH. Corn grain yield increased with increasing N rates. The
maximum grain yield of 12.7 Mg ha-1 was obtained for N4
compared to the lowest yield of 8.3 Mg ha-1 from the unfertilized
plots (N0). Soil bulk density decreased with increasing N level and
ranged from 1.21-1.33 Mg m-3 in continuous corn and 1.25-1.37 Mg m-3
in rotation corn. Water stability of aggregates increased with increasing rates
of N from 45.3% (N0) to 53.8% (N4). Mean weight diameter
of the aggregates decreased with increasing rates of N fertilizer application,
ranging from 0.75 mm for N0 to 0.51 mm for N4. There was
an increasing trend in SOC pool with the addition of N fertilizers, ranging
from 68 Mg ha-1 (N0) to 80 Mg ha-1 (N3)
for continuous corn and from 65 kg ha-1 (N0) to 74 Mg ha-1
(N4) for rotation corn in 0-30 cm depth. The rate of soil
carbon sequestration for high rate of N application is 600 kg ha-1yr-1
for continuous corn and 450 kg
ha-1yr-1 for rotation corn. This study shows the critical role of N and crop rotation in building-up of soil organic carbon stock and mitigating global climate change.
Jenkins, Jennifer (University of Vermont, 590 Main St., Burlington, VT 05405; Phone: 802-656-2953; Fax: 802-656-2995; Email: jennifer.c.jenkins@uvm.edu)
Carbon Stocks and Fluxes
in Urban and Suburban Residential Landscapes
J.C. Jenkins*, M.L. Cadenasso, P.M. Groffman, S.T.A. Pickett, J.M. Grove, M.L. Cox
Substantial carbon (C) sequestration occurs in residential systems, though the residential land base is largely excluded from national greenhouse gas inventories. In fact, EPA’s 2002 inventory of US Greenhouse Gas Emissions and Sinks reports that, of the 188 Tg C sequestered in the US, 87% (164 Tg C) was sequestered in forests (including wood products and soils), while 3% (6 Tg C) was sequestered in agricultural soils. Fully 8% of the C sequestered nationwide in 2002 (16 Tg C) was stored in urban trees (both above- and below-ground) and the remaining 1% (3 Tg C) was stored in landfills as yard trimmings and food scraps. Despite the large land area occupied by residential systems, the importance of these areas for the human population, the aesthetic similarity of residential land all across the country, and the rapid conversion of land to these residential uses, very little is currently known about the biogeochemical processes occurring in urban and suburban residential areas. Our work will begin to fill this knowledge gap by quantifying C stocks and fluxes, and the factors that drive them, in residential neighborhoods of metropolitan Baltimore, Maryland. We are in the early stages of a project designed to: a) quantify key C stocks and fluxes in the vegetated component of the residential landscape; and b) identify the relative importance of urban ecosystem structure, soil functional properties, historical land use, and land management practices as drivers of C stocks and fluxes in residential systems. Though this work is taking place as part of the Baltimore Ecosystem Study (BES), an NSF-supported Long Term Ecological Research (LTER) site, it will test methods that can be used in assessments of C cycling in residential areas in other regions, laying the groundwork for future cross-city analyses. In addition, this study will contribute to the ongoing effort to characterize the Northern Hemisphere C budget by providing data on components of the C budget that have largely been ignored.
Jenkins, Jennifer (University of Vermont, 590 Main Street, Burlington, VT, 05405; Phone: 802-656-2953; Email: jennifer.c.jenkins@uvm.edu)
A Comprehensive Database of Diameter-Based Biomass Regressions for North American Tree Species
J.C. Jenkins, D.C. Chojnacky, L.S. Heath, R.A. Birdsey
Estimates of national-scale
forest carbon (C) stocks and fluxes are typically based on allometric
regression equations developed using dimensional analysis techniques. However, the published literature can be
inconsistent and incomplete with respect to large-scale forest C estimation and
few off-the-shelf resources have been available for allometric estimation of
tree biomass. In this project, we used
primary sources whenever possible to compile all available (2600+)
diameter-based allometric regression equations for estimating total aboveground
and component biomass, defined in dry weight terms, for tree species found in
the United States. The database includes
information on the numbers of trees sampled to develop each equation, the
maximum and minimum dbh values over which the equation is valid, regression
statistics as published by the original authors, and other information valuable
for users of the equations. The
compilation is published as a database and is available in both paper and
electronic format (Jenkins, J.C., D.C. Chojnacky, L.S. Heath, and R.A. Birdsey.
2004. Comprehensive Database of Diameter-based Biomass Regressions for Untied
States Tree Species. Gen. Tech. Rep. NE-319. Newtown Square, PA: U.S.
Department of Agriculture, Forest Service, Northeastern Research Station). It is also available at
http://www.fs.fed.us/ne/global/. This
database is the underlying source of material for our 2003 paper entitled
“Consistent National-Scale Biomass Estimators for United States Tree Species”
(Forest Science 49(1): 12-35). In
addition to its value as a source for our generalized national-scale equations,
we envision this database as a user-friendly and comprehensive resource for
researchers and practitioners interested in quantifying standing stocks of
biomass based on forest mensuration data.
Jenkins, Jennifer (University
of Vermont, 590 Main St., Burlington, VT, 05405; Phone: 802-656-2953; Fax:
802-656-2995; Email: jennifer.c.jenkins@uvm.edu)
Linking Extensive Monitoring Systems for Complete C Balance Estimation: A Pilot Test in the Catskill Mountains, NY (USA)
J.C. Jenkins*, P.S. Murdoch, R.A. Birdsey
Methods are fairly well-developed for estimating terrestrial carbon (C) cycling rates at the plot scale for small-scale ecosystem science research. Techniques also exist to estimate terrestrial and aquatic C cycling rates at large scales, using stream monitoring data, inventory datasets, and/or modeling approaches. Still undeveloped, though, are techniques for linking the two types of monitoring datasets (terrestrial and aquatic) for complete C cycle estimation at both intensive and extensive study sites. These techniques are critical to a comprehensive understanding of net C exchange between terrestrial and atmospheric systems. We report results of a pilot test conducted as part of the interagency Collaborative Environmental Monitoring and Research Initiative (CEMRI) to link terrestrial and aquatic monitoring data for estimation of all components of the C cycle in a forested watershed in the Neversink Basin, in the Catskill Mountains of New York. Despite the homogeneity of soil conditions and forest types in the watershed, we found substantial differences in soil C stocks, aboveground biomass, annual wood biomass increment, annual litterfall, and modeled soil respiration among stands of similar forest type and similar age. We also found that downstream export of dissolved and suspended C in streamwater is directly related to the concentration of total suspended solids (TSS) in streamwater, and accounts for a substantial proportion of the C fixed aboveground. The methods tested here will provide a template for similar efforts to integrate monitoring systems for complete C cycle estimation in regions where extensive monitoring systems exist.
Johansson, Maj-Britt (Swedish University of Agricultural Sciences (SLU),Uppsala, SE 750 07, Sweden; Phone: +46(0)18-672232; Fax: +46(0)18-673470; Email: Maj-Britt.Johansson@sml.slu.se)
M.B. Johansson*, A. Nilsson
Site data from the National Forest Inventory (NFI) and the National Survey of Forest Soils and Vegetation (NSFSV) in Sweden were used to investigate the impact of tree species on soil carbon content. From the NFI, data on tree species composition were utilized. Soil characteristics such as soil texture, soil type, moisture conditions and chemical characteristics, e.g. carbon and nitrogen content in different horizons, were obtained from the NSFSV for the same sites. The amount of soil carbon to 1 m depth was calculated for pure middle-aged stands of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), silver birch (Betula verrucosa Ehrh.) and downy birch (Betula pubescens Ehrh.), the commonest Swedish forest trees. Only sites were selected where the site demands of all four tree species were fulfilled, viz. sandy and finer-textured soils, iron podzols, iron-humic podzols and mesic to mesic-moist soils. The soil carbon content was positively and linearly related to the effective temperature sum P less than 0.001, R2 = 0.38, n = 323). Norway spruce and birch forests had significantly more soil carbon (36 t ha-1) than Scots pine forests, but did not differ mutually. To discover whether changed species composition, i.e. a spruce/birch admixture in pine forests, would affect the soil carbon content, relationships between total soil carbon (to 1 m depth) and tree species composition were examined. The sites were selected according to the criteria above. Differences among sites in climate and fertility probably contributed to the absence of a strong relationship between the proportion of (spruce + birch) in pine forests, and soil carbon content. Tree-species composition alone explained only 11% of the variation (P less than 0.0001). When other site variables were included in a multiple regression analysis, a four-factor relationship which included (proportion spruce + birch), (temperature sum), (nitrogen concentration in the B-horizon) and (proportion spruce + birch)2, the relationship was highly significant (P less than 0.0001, n = 794) and explained 48% of the variation. Data on tree-species composition and the other site variables above were used to estimate the average soil carbon content in individual cells in a grid covering the forests of the country by means of the relationship. Maps were produced by weighted interpolation, to show the soil carbon pool in Swedish forests with the current tree-species composition. Soil carbon increased from an average of less than 80 ton C ha-1 in the north to greater than 140 ton C ha-1 in the south. These figures agree with other estimates. Maps were also produced to show soil carbon content in Swedish forests after a 10% increase in the spruce/birch fraction above the present level. Regions were identified in which a changed species composition significantly increased the soil carbon content.
Johnson, Jane (USDA-ARS, 803 Iowa Ave, Morris, MN, 56267; Phone: 320-589-3411 ext 131; Email: jjohnson@morris.ars.usda.gov)
Preliminary Observations of Greenhouse Gas Emission from
Contrasting Management Scenarios in the
J.M.F. Johnson*, D. Archer, N.W. Barbour, J. Eklund
To identify and develop economically viable and environmentally sustainable farming systems, the risks and benefits associated with various management strategies need to be characterized. It is hypothesized that minimized tillage and diversified crop rotation can improve soil quality and enhance sustainability. Long-term cropping systems field plots were established in 2002 in central MN, to compare tillage, rotation and fertilizer treatments. Greenhouse gas emission was monitored in a subset of treatments selected to represent three different scenarios: “business as usual,” “maximum C sequestration,” and “optimum greenhouse gas benefits.” The “business as usual” scenario has conventional tillage (chisel or moldboard plow), and receives high fertilizer inputs in a corn-soybean rotation. The “maximum C sequestration” scenario is strip tilled with a mole-knife, and receives high fertilizer inputs in a corn-soybean-wheat/alfalfa-alfalfa rotation. The “optimum greenhouse gas benefits” scenario is strip tilled with a mole-knife but receives no fertilizer inputs in a corn-soybean-wheat/alfalfa-alfalfa rotation. Nitrous oxide and carbon dioxide emission were monitored using vented static chambers, from early April through late November 2004. Collateral information collected included weather data, soil temperature and volumetric soil moisture at time of sampling. Two collars were installed in each plot sampled: for row crops, one collar was positioned adjacent to the row and the second collar was in the inter-row; in wheat and alfalfa, collars were positioned randomly in regards to plants. A total of 40 plots (80 collars) were sampled biweekly. The largest instantaneous and cumulative nitrous oxide flux occurred from alfalfa plots. The pattern of nitrous oxide emission from corn plots varied by tillage treatment, with peak flux occurring in April from the strip tilled plots and mid-July from the conventional tillage corn plots (corresponding to a significant rainfall event). Large episodic nitrous oxide fluxes were not observed from soybean or wheat.
Johnson, Jon D. (Washington State University - Puyallup Research & Extension Center, 7612 Pioneer Way E., Puyallup, WA, 98371; Phone: 253-445-4522; Fax: 253-445-4569; Email: poplar@wsu.edu)
J.D. Johnson*
The burning of fossil fuels for energy generation has resulted in the steady increase in atmospheric carbon dioxide concentration over the last century and may have profound effects on the global environment and economy, resulting from the global warming brought on by the greenhouse effect. Above- and below-ground carbon sequestration rates were determined from destructive harvests of poplar stands ranging from 2 to 8 years old representing four commercial varieties of hybrid poplar growing on the west and east side of the Cascade Mountain range. Prior to sampling, each tree was characterized by above ground tree dimensions (height and diameter) that were then used to develop algorithms to predict standing carbon. In addition, soil carbon sequestration was determined from soil cores collected to a depth of 1 m from around each harvest tree and compared to cores collected from adjacent agricultural fields. An estimate of both labile and non-labile soil carbon was determined using a boiling water extract.
Johnson, Patrick (Zimmerman Associates, Inc., 4404 Holter Court, Jefferson, MD, 21755; Phone: 301-371-3584; Fax: 301-371-3709; Email: pjohns@erols.com)
BioSAR: A VHF Radar for the Airborne Measurement of Terrestrial Biomass and Carbon
P.W. Johnson*
A new airborne radar has been developed for NASA and DOE to remotely measure above ground terrestrial biomass and embedded carbon. BioSAR operates at 80-120 MHz and can measure biomass and carbon in stands of 100 to over 300 tons of biomass per hectare. Operational flights over STRI ground truthed areas in Panama demonstrated an accuracy of +/- 10%. The system is very small, light weight and low power and can fit easily into a single engine aircraft. The system has been installed and surveys conducted on three different aircraft including a Piper Aztec and the NASA C-130. The system is currently installed and operational in a Twin Otter. A DOE mission with BioSAR and the NASA PALS laser radar system is planned for February 2005 over forested areas in North Carolina to measure biomass, embedded carbon, and canopy structure. The results of the February mission will be discussed.
Kadam, Kiran (PureVision Technology, Inc., 511 McKinley Ave., Fort Lupton, CO, 80621; Phone: 303-857-4530; Fax: 303-857-0323; Email: Carl@PureVisionTechnology.com)
Greenhouse Gas Reduction Opportunities Via Processing Agricultural Residues in Rural Biorefineries
K.L. Kadam*, E.R. Lehrburger, C.H. Lehrburger
A new biorefining process referred to as “reactive
fractionation” is presented in the context of greenhouse gas (GHG) reduction
using corn stover and wheat straw as feedstocks. This closed-loop process is
under development and is being optimized using a continuous 10-kg/hr process
development unit. The novel biomass fractionation technology relies on an
extruder apparatus that minimizes reagent and water use and accomplishes
biomass fractionation in a relatively short time compared to traditional
biomass pretreatment or pulping processes. This two-stage approach dissolves
and separates hemicellulose and lignin from biomass in sequential stages,
leaving relatively pure cellulose. Enzymatic hydrolysis of this cellulose
stream requires significantly lower enzyme loadings for hydrolysis with a
corresponding reduction in production costs. The hemicellulose sugars captured
in the hydrolyzate liquor and cellulose-derived glucose are used to produce
ethanol. Ethanol produced from lignocellulosic feedstocks can be used as a
renewable fuel or fuel oxygenate. The non-sulfur lignin is highly reactive and
can be used for value-added products or for on-site co-generation of steam and
electricity. This paper quantifies the GHG reduction potential in such a process
using agricultural residues. The offset credits attributable to the
bio-products and bio-energy generated in the proposed biorefinery configuration
are computed by comparing, on an energy-equivalent basis, ethanol vs. gasoline
combustion, electricity generation from lignin vs. coal, and biogas vs. natural
gas combustion. Environmental impacts will be discussed in terms of net CO2
emissions and the total greenhouse gas potential from major GHGs, i.e., CO2,
CH4, and N2O. Greenhouse gas reduction would stem from
the following attributes of the biorefinery scenario: proposed process is a net
producer of energy, a portion of the total energy consumption is from renewable
sources, and the fossil-derived CO2 emissions are
lower because the carbon dioxide released from ethanol, methane and lignin
combustion is eventually recycled via photosynthesis. Potential monetization of
CO2 offset credits will be reported based on current clearing prices
at the Chicago Climate Exchange. The results for criteria pollutants such as
carbon monoxide, non-methane hydrocarbons, SOx, NOx, and particulates will also
be generally discussed. Besides affecting global issues of climate change and
conservation of natural resources, e.g., fossil reserves, the proposed
biorefinery scenario also impinges positively on local air quality. Results
will be presented for a commercial scenario based on a single biorefinery
configuration, which will be extrapolated to full market penetration defined by
corn stover and wheat straw availability on a sustainable and economic basis in
the Central Great Plains (U.S.). The projected impacts for utilizing a portion
of these abundant feedstocks will be reported to emphasize the potential impact
of the proposed technology in reducing GHG emisions. Although specific for the
agricultural states in the American Midwest, such information should also be
generically applicable to other regions of North America and elsewhere in
processing of waste/excess biomass via the biorefinery scenario. Successful
commercialization of such projects will result in similar positive
environmental impact.
Kaye, Jason (Penn State
University, Dept. of Crop and Soil Sciences, 116, ASI Building, University
Park, PA, 16802; Phone: 814-863-1614; Fax: 814-863-7043;
Email: jpk12@psu.edu)
J.
Kaye*, J. Romanya, R. Vallejo
Fire regimes constrain carbon (C) accumulation in forests and recent research suggests that forest fires play an important role in C budgets for countries with expansive dry temperate forests. In Spain, dry, fire prone Mediterranean woodlands cover much of the country, including the northeast portion of Cataluna, where we used a chronosequence to estimate changes in ecosystem C storage following stand-replacing fires. In 2001, we sampled eight sites that ranged from 1 to 30 years post-fire. Several of these sites had been sampled for C storage in 1985 and 1989, so we were able to compare the chronosequence approach with repeated sampling of individual sites. Post-fire C accumulation in plants was low (less than 400 g C/m2) when shrubs dominated early in succession, but became substantial (about 5000 g C/m2) later in succession when pines became dominant. Soil C sequestration varied by layer. The surface organic horizons (Oi plus Oe) accumulated C rapidly early in succession and reached a maximum storage of 600 g C/m2. In contrast, the lower organic horizon (the Oa horizon) lost 200 to 300 g C/m2 within 15 years of the fire. Surface mineral soils (0 to 5 cm) lost as much as 2000 g C/m2 within the first 15 years following fire, but sites were highly variable in mineral soil C loss. To fully understand post-fire C storage in these woodlands, future research should focus on controls on pine regeneration and C losses from surface mineral soils.
Kemanian, Armen R. (Washington State University, Biological Systems Engineering Dept., Smith Hall, Pullman, WA, 99164-6120; Phone: 509-335-3661; Fax: 509-335-2722; Email: armen@wsunix.wsu.edu)
Assessing the Usefulness of Simple Mathematical Models to Describe the Soil Carbon Dynamics
A.R. Kemanian*, V.S. Manoranjan, D.R. Huggins, S.O. Stockle
The rate of C storage in the soil (Cs) depends on the balance between the inputs of C from organic residues (Ci) and the outputs due to microbial oxidation of organic matter. Due to the complexity of the processes affecting the input and output rates, analytical solutions to Cs dynamics are not feasible. Partial information regarding particular processes like residue decomposition and Cs turnover, together with the effect of environmental factors on microbial activity, have been compiled and encapsulated in so-called mechanistic models of soil organic matter dynamics. The use of these models has been promoted under the assumption that complex interactions among several factors are accounted for quantitatively. It must be noted, however, that the structure of these mechanistic models is relatively simple. We hypothesize that simple mathematical models could be equally or more effective at representing soil carbon dynamics. We present empirical models of soil C dynamics of the general form dCs/dt = h(Cs)Ci + k(Cs)Cs, where h and k are the residue humification and apparent soil C decomposition coefficients. The simplest solution to this equation results from assuming that h and k are constant, which implies that under steady state Cs = hCi/k. This implies that the storage capacity of the soil is linearly dependent on Ci. There is evidence, however, that soils have a finite capacity to store C. In addition, the Cs constituents have different turnover rates i.e. k is a weighted average of the individual k’s of each soil C fraction. We know that as Cs changes k does not remain constant, as each individual C constituent changes at different rates. We explore the behavior of models in which h and k are functions of Cs. The general behavior of these models in response to changes in Ci and Cs is presented. When possible, some models were parameterized based on observed values of soils at steady state and a small set of assumptions. The analysis indicates that making h a function of Cs provides a simple way of representing a “Cs carrying capacity”. Making k a function of Cs provides a means for accelerating the turnover rate as Cs increases, with the underlying assumption that the higher the Cs content the lower the soil recalcitrant C fraction. As a result, if properly parameterized, a single mathematical function can be used for different soil layers provided that the texture does not change dramatically and that the inputs from roots at different depth are known. The effect of residue composition such as variations in lignin content on h can also be accommodated. The analysis of these models suggest that the set of rules usually used in mechanistic simulation models to allocate carbon to different C pools (i.e. humification rules) should depend not only on soil texture but on the C level of each pool. These simple models could, therefore, not only be useful to predict Cs dynamics but also provide feedback information to improve existing mechanistic models.
Kemanian, Armen (Washington State University, Biological Systems Engineering Dept., Smith Hall, Pullman, WA, 99164-6120; Phone: 509-335-3661; Fax: 509-335-2722; Email: armen@wsunix.wsu.edu)
Modeling Carbon and Nitrogen Cycling and Greenhouse Gas Emissions from Agricultural Systems
C.O. Stockle, A.R. Kemanian*, D.R. Huggins, H.P. Collins
A model of carbon and nitrogen cycling (CNC) was developed
and integrated into the CropSyst cropping systems model. The main reason for
developing our own model was to build upon the strength of CropSyst in
simulating the soil water balance and temperature, and to take advantage of the
already validated robustness of CropSyst in simulating crop biomass production
and therefore the input of C to the soil under a variety of climates and
management scenarios. The criteria to develop the CNC model were functionality
and that the definition of pools and transfer rates among pools were measurable
or inferable from field or laboratory measurements. The structure of the soil
carbon subroutine has a resemblance with the model presented by Verberne et al.
(1990), but includes several modifications. The CNC model runs on an hourly
time step. The soil is divided in a user-defined number of layers of varying
thickness. Inputs of carbon are from crop residues, senescent leaves, and dead
roots. No explicit allowance was made for root C deposition, but in practice it
can be integrated into the root turnover. Each time there is an input of
residue or dead roots in a given soil layer, a new carbon residue pool is
generated. Similarly, tillage events result in new incorporated pools. Carbon
inputs such as crop residues, roots, and manure are divided in three fractions:
lignin, structural fraction, and non-structural fraction, the latter having the
smallest turnover rate. Soil carbon is divided in four pools of decreasing
turnover rates: microbial biomass, labile, metastable, and stable pools. Carbon
decomposition from the residue and the soil C pools is mediated by the biomass
pool, except for lignin. Each microbial attack renders carbon dioxide and
microbial biomass. The products of microbial decomposition are allocated to the
different soil C pools following rules dependent on the clay content, similar
to those presented by Parton et al. (1994). The microbial biomass pool plays a
functional role and no separation between active and dormant microbial biomass
was attempted. All decomposition processes are simulated using first order
kinetics. Rates of microbial-mediated processes are adjusted by temperature and
moisture factors operating multiplicatively. Soil temperature is modeled
following an energy balance approach, and soil moisture using a finite
difference method. Nitrogen cycling is linked to the flow of carbon, except for
the ammonium and nitrate pools that are independently modeled. Total
denitrification and the fraction of N lost as nitrous oxide are modeled as a
function of nitrate concentration, soil respiration rate, and soil moisture.
Tillage effects on the decomposition rate are incorporated into the model. Each
tillage event determines a transfer of carbon and nitrogen from the stable and
metastable pools to the labile pool. The transferred carbon slowly returns to
the metastable pool unless there are more tillage events. These transfers
represent in a simple manner aggregate break-up due to mechanical disturbance
and the subsequent aggregation. Parameterization of the CNC model was performed
by interpretation of information in the literature and by interpretation of our
own data on soil carbon dynamics. Simulations for different cropping systems in
the Pacific Northwest and a sensitivity analysis of some of the model
parameters are presented.
Kempka, Richard G. (Ducks Unlimited, Inc., National Headquarters, One Waterfowl Way, Memphis, TN, 38120-2351; Phone: 901-758-3795; Fax: 901-758-3850; Email: dkempka@ducks.org)
R.G. Kempka*
Most energy companies have reviewed present and
future greenhouse gas liabilities as part of corporate strategic planning and
are actively analyzing options to reduce their greenhouse gas emissions profiles
either by reducing company-generated emissions or by offsetting company
emissions. Companies that are proactive in addressing greenhouse gas emissions
are positioning themselves as leaders in the market place. Well-designed
terrestrial carbon sequestration projects – such as reforestation and grassland
restoration - offer cost-effective carbon offsets, as well as benefits to local
communities, wildlife habitat, and associated biodiversity. In addition,
properly designed projects can provide other vital eco-assets such as cleaner
water and flood control. Corporate
investment in terrestrial carbon sequestration offsets today will yield
significant carbon benefits in future years.
This presentation will discuss credible, cost-effective, high-quality terrestrial
carbon sequestration offset opportunities.
Wetlands are collectively a large global carbon reservoir, storing nearly 33% of all soil organic carbon even though they represent only about 4% of the landmass. Prairie potholes and forested wetlands represent over 50% of the wetlands in the conterminous U.S. Forested wetlands are known to be significant carbon sinks, but less information exists regarding carbon sequestration value of prairie wetlands. Prairie soils, in general, are significant reservoirs of terrestrial carbon. Two key regions for wetlands are the Prairie Pothole Region in the north central U.S., and the lower Mississippi Alluvial Valley extending from the southern tip of Illinois to southern Louisiana. Both regions have experienced millions of acres of land clearing, agricultural conversion and wetland and associated upland habitat loss that have directly contributed to several important local and regional environmental issues (i.e., non-point source water quality, increased flooding, Gulf of Mexico hypoxia, etc.). The emerging carbon market could provide significant conservation opportunities with positive impacts for these regions if appropriately planned, targeted and delivered. A significant proportion of the marginal agricultural lands could be restored to the former prairie grassland and bottomland hardwood systems with funding from carbon investors, thereby providing environmental benefits to society and an economic return to the farmers. However, these kinds of projects must abide by important scientific and policy guidelines to attract investors and have ecological merit. This presentation will discuss Ducks Unlimited, Inc., and partners’ efforts to develop quality carbon offset projects and promote collateral-benefits of terrestrial sequestration via wetland and upland restoration. It will discuss the potential role of wetlands in this emerging market and how they may fit into corporate strategic planning that is actively analyzing options to reduce their greenhouse gas emissions in advance of a potential regulatory environment.
Kinsman, John (Edison Electric Institute, 701 Pennsylvania Avenue, NW, Washington DC, 20004, Phone: 202-508-5711; Fax: 202-508-5150; Email: jkinsman@eei.org)
Overview of Electric Power Industry UtiliTree Carbon Company and PowerTree Carbon Company Programs
J. Kinsman*
The electric power industry has a long history of involvement with traditional forest management and tree-planting programs, through preserving forest lands for both recreational use and wildlife habitat, tree maintenance around power lines, education of homeowners on tree placement around power lines, and commercial forestry on electric company-owned lands. Many companies have also initiated forestry projects specifically to conserve energy and to offset CO2 emissions. Since the Energy Policy Act established the "Section 1605(b)" voluntary data base system, electric power companies have reported a large number of forestry projects to address CO2.
In 1995, the non-profit UtiliTree Carbon Company was established in 1995 by 41 utilities to sponsor a collection of projects that manage greenhouse gases, especially CO2 . The projects consist of a diverse mix of rural tree planting, forest preservation, forest management, and research efforts at both domestic (Louisiana, Mississippi, Arkansas and Oregon) and international (Belize and Malaysia) sites. The UtiliTree Carbon Company has committed slightly over $2.5 million to fund these projects.
In addition, several collaborative programs among different companies in the industry have been initiated. In 2003, 25 companies established the PowerTree Carbon Company, LLC, a voluntary consortium of 25 leading U.S. electric power companies that have committed $3 million to establish six bottomland hardwood reforestation projects in the Lower Mississippi Alluvial Valley (LMAV).
Based on our experience, we will discuss the benefits of such efforts plus key policy issues of monitoring, verification, permanence and leakage.
Kissel, David (University of Georgia, Dept. of Crop and Soil Sciences, Athens, GA, 30602; Phone: 706-542-5350; Email: fchen@uga.edu)
Similarity Analysis for Mapping Soil Organic Carbon with Remotely Sensed Imagery
F. Chen, D.E. Kissel*, L.T. West, D. Rickman, J.C. Luvall, W. Adkins
High-resolution, remotely sensed imagery of bare soil has been successfully used to quantitatively map the spatial variation of the organic-C concentrations (SOC) of surface soil (Chen et al., 2000; Chen et al., 2005). This method requires each field to be sampled and mapped separately. Upon examination of remotely sensed images that consist of several fields, some fields look similar with regard to image properties such as the color histogram. By using similarity analysis, it may be possible to group similar fields, analyzing and mapping them together, thereby reducing costs further. The objective of this study was to examine image similarity of agricultural fields, relate image similarity to soil properties, and map SOC for a group of fields at one time. Three types of features (feature vectors), including color histograms, color slope magnitudes, and Haar wavelets, were extracted to analyze field similarity with computer programming. Two methods, similarity clustering with Euclidean distance and similarity matching with the Ward neural networks were used for matching between extracted features. Dissimilarity distance (for the clustering method) and coefficient of determination (for the neural network method) were used for similarity ranking of images (fields). Based on the similarity result, soil organic carbon maps of two crop fields were created with a single processing.
Klik, Andreas (BOKU-University of Natural Resources and Applied Life Sciences, Vienna, A-1190, Austria, Phone: 00431-360065472; Fax: 00431-360065499; Email: andreas.klik@boku.ac.at)
A. Klik*, T. Fruhmann, A. Mentler
Carbon dioxide is an important greenhouse gas (GHG) accounting for 60% of the total GHG effect. Soil is a major source for atmospheric CO2. In the event of growing threats of global warming due to GHG emissions, reducing CO2 emissions by sequestering C in the soil is a prime importance. Soil management practices like increasing soil organic carbon content, reduced tillage and mulching can play an important role in sequestering C in soil. Some data about CO2 emissions from agricultural used soils are already available for South (Resck et al., 2002) and North America (Jacinthe et al., 2002; Reicosky, 1997) as well as for Asia but nearly no data exist for Europe. In summer 2004 a study was performed on an agricultural field in Austria. The objective of this study was to investigate and evaluate effects of tillage practices on CO2 emission rates. Following tillage practices were compared: 1) conventional tillage (CT), 2) conservation tillage with cover crop (CS), and 3) direct seeding with cover crop (DS). Crops were removed in spring and soil was kept bare throughout the measuring period. Precipitation and air temperature were measured continuously in 5-min intervals. From June to August CO2 emissions were measured in 15 day intervals by closed chamber method (PVC chamber, diameter 27.8 cm). CO2 accumulation was monitored over 120 min and air samples then analyzed with a GC-TCD. Four times during the measuring period, soil samples were taken from 0-5, 5-10 and 10-30 cm depth. Soil water content, soil organic carbon content, soil respiration, ß-glucosedase and dehydrogenase were measured and determined, respectively. Preliminary results show calculated C losses between 365 kg (CT) and 440 kg (DS) per hectare from June to August. No significant differences were observed between treatments. This can be explained by the fact that the spring period where tillage operations are performed was not covered by measurements
Kong, Angela (University of California-Davis, Dept. of Plant Sciences, PES Bldg., One Shields Ave., Davis, CA, 95616; Phone: 530-754-7537; Fax: 530-752-4361; Email: aykong@ucdavis.edu)
Effect of Organic and Mineral Nutrient Sources and the Role of Aggregate Dynamics on Carbon Sequestration Across Conservation and Standard Tillage Farming Systems
A.Y. Kong*, S.J.
Fonte, J. Six, D.C. Bryant, C. Van Kessel
Developing sustainable cropping system management practices that enhance agricultural sustainability, reduce negative environmental impacts, and attenuate anthropogenic greenhouse gas (GHG) emissions rests to a large extent on our understanding of C turnover, N synchrony, and C and N storage in soils. This study focused on: 1) elucidating the linkage between organic resources (OR), mineral fertilizer (MF) additions, tillage and aggregate dynamics, and 2) how this linkage controls the cycling of N and the sequestration of C in Mediterranean cropping systems. Soil and GHG (CO2 and N2O) samples were collected from standard (ST) and minimum tillage (MT) treatments within organic (OMT), conventional (CMT), and low-input (LMT) maize-tomato cropping systems. Soil samples were separated into three aggregate size classes (macroaggregates: greater than 0.25mm, microaggregates: 0.053-0.25mm, and silt&clay: less than 0.053 mm) and into three SOM fractions within the macroaggregate fraction (cPOM: greater than 0.25mm, mM: 0.053-0.25mm, and silt&clayM: less than 0.053mm). We calculated turnover of 13C- and 15N-labeled legume residues (OMT and LMT systems) and mineral fertilizer (CMT system) among the fractions and found faster turnover of 15N in the CMT systems than the OMT and LMT systems. Higher SOC, SON, and aggregate stability were observed in the OMT than the CMT and LMT systems, regardless of tillage practices. However, faster turnover of 15N was measured in the CMT systems than the OMT and LMT systems. Preliminary measurements indicated significant crop treatment effects on N2O fluxes. Our results suggested that the LMT systems under CT led to an optimal rate of C and N cycling.
Kong, Angela (University of California-Davis, Dept. of Plant Sciences, PES Bldg., One Shields Ave., Davis, CA, 95616; Phone: 530-754-7537; Fax: 530-752-436; Email: 1aykong@ucdavis.edu)
Carbon Input, Aggregate Stability, and Carbon Stabilization in Mediterranean Cropping Systems
A.Y. Kong*, J. Six, R.F. Denison, C. Van Kessel
One of our current challenges is to provide credible evidence that agricultural practices can sequester significant amounts of C and to quantify the underlying mechanisms, capacity, and longevity of agricultural lands to serve as C sinks. The objectives of this study were to (1) quantify the relationship between C input and SOC sequestration in whole soil and SOM fractions and (2) evaluate mechanisms of long-term SOC stabilization across a gradient of C input levels. Soil samples from 10 cropping systems at the Long-Term Research on Agricultural Systems (Davis, CA) were separated into four aggregate size classes (large macroaggregates: greater than 2mm, small macroaggregates: 0.25-2mm, microaggregates: 0.053-0.25mm, and silt&clay: less than 0.053mm) and into three SOM fractions within large and small macroaggregates (cPOM: greater than 0.25mm, mM: 0.053-0.25mm, and silt&clayM: less than 0.053mm). Estimates of C input from corn, wheat, and tomato residues were empirically derived from relationships between yield and biomass-C (above- and belowground), while C input from legume cover crops and compost was estimated from annual application rates. We found a positive correlation between cumulative C input and SOC (r2=0.70, p less than 0.003), while aggregate stability increased linearly with greater C input (r2=0.75, p=0.001) and SOC (r2=0.63, p =0.006), respectively. We observed that aggregate-C shifted from the less than 0.053mm fraction in low C input systems to the large and small macroaggregate fractions in high C input systems, with a majority of the increase in C input-derived SOC preferentially stabilized in the mM fraction. Hence, the mM fraction an ideal indicator for C sequestration potential in sustainable agroecosystems.
Kunda, Maithilee (MIT, 320 Memorial Drive, Cambridge, MA, 02139-4307; Phone: 617-225-8550; Email: gum@ornl.gov)
M. Kunda*, G. Marland, B. Schlamadinger, L. Canella
Many studies have suggested that carbon sequestration in terrestrial ecosystems can be an effective strategy for mitigating climate change. An increase in the carbon stocks of the biosphere results in a decrease in atmospheric CO2. However, changes in the terrestrial biosphere have climatic impacts beyond affecting the atmospheric concentration of CO2. In particular, changes in the surface albedo can have a significant impact on the Earth’s climate. Several recent studies suggest that the effect on mean Earth surface temperature due to changes in albedo, for instance from increasing biosphere carbon stocks, may be of comparable magnitude but opposite in sign to the temperature effect of removing the CO2 from the atmosphere. This is particularly true if, for example, forests are established in areas where there is extensive snow cover and hence the albedo difference between forest and non-forest is large. We use simple examples to demonstrate the relative magnitudes of the carbon and albedo effects on mean Earth-surface temperature and how these can be expected to evolve with time. These illustrations suggest that, in terms of climate protection, we re-examine the relative merits of: 1) protecting existing forests vs planting forests where forests did not previously exist, and 2) managing forests to replace alternate fuels or energy-intensive products vs. managing forests to accumulate and store carbon.
Kurkalova, Lyubov (Iowa State University, 560A Heady Hall, Ames, IA, 50011-1070; Phone: 515-294-7695; Fax: 515-294-6336; Email: lyubov@iastate.edu)
Carbon Sequestration in the Upper Mississippi River Basin: Implications for Geographical Distribution of Economic Benefits
H. Feng, L.A. Kurkalova*, C.L. Kling, P.W. Gassman
This study investigates the carbon sequestration potential and co-benefits from policies aimed at retiring agricultural land in the Upper Mississippi River Basin, a large, heavily agricultural area. We extend the empirical measurement of co-benefits from the previous focus on environmental benefits to also include economic transfers, which have often been mentioned as a co-benefit, but little empirical work measuring the potential magnitude of these transfers has previously been undertaken. We compare and contrast five targeting schemes, each based on maximizing different physical environmental measures, including carbon sequestration, soil erosion, nitrogen runoff, nitrogen leaching, as well as the area enrolled in the program. In each case, the other environmental benefits and economic transfers are computed. We find that the geographic distribution of co-benefits (including economic transfers) varies significantly with the benefit targeted, implying that policy design related to targeting can have very important implications for both environmental conditions and income distributions in sub regions.
Kustas, William (USDA-ARS, HRSL, Bldg. 007, BARC-WEST, Beltsville, MD, 20705; Phone: 301-504-8498; Fax: 301-504-8931; Email: bkustas@hydrolab.arsusda.gov)
Monitoring Net Carbon Exchange Over Agricultural Landscapes with a Remote Sensing-Based Model
M.C. Anderson, W.P. Kustas*, J.M. Norman
New generation carbon-flux-monitoring campaigns are recognizing the need to establish connectivity between intensive surface observations, typically collected at a point or a distributed set of points, by placing them within a regional context using modeling supported by remote sensing. Large-scale carbon flux networks, such as AmeriFlux and EuroFlux, will require robust methodologies for upscaling and integrating observations made at individual towers to be able to draw regional inferences regarding terrestrial carbon cycles. An existing nested remote sensing scheme, designed for mapping surface water and energy flux distributions at spatial resolutions from 10 m to 5 km, has recently been modified to incorporate an analytical light-use efficiency (LUE) submodule for modeling bulk canopy conductance and carbon uptake. This analytical LUE technique was distilled out of a more detailed soil-plant-atmosphere model for purposes of practical application, and has been demonstrated to provide good predictions of coupled transpiration and carbon assimilation fluxes using only a modest amount of input data. This modeling system is applied to remote sensing imagery over Oklahoma and the output is compared to carbon flux measurements collected during the intensive field experiment. Results illustrate the utility of the technique for large scale monitoring of net carbon exchange for agricultural landscapes.
Laird, David (USDA-ARS, NSTL, 2150 Pammel Drive, Ames, IA, 50011; Phone: 515-294-1581; Fax: 515-294-8125; Email: laird@nstl.gov)
Impact of Nitrogen Fertilization and Crop Rotations on Soil Organic Carbon Sequestration and Soil Quality
D.E. Russell, D.A. Laird*
We analyzed the impact on soil organic C (SOC) of four N fertilization rates (0–270 kg N ha-1) and four cropping systems: continuous corn (CC); corn-soybean (CS); corn-corn-oat-alfalfa (CCOA), and corn-oat-alfalfa-alfalfa (COAA). Soils were sampled in 2002, years 23 and 48 of the experiments located in northeast (Nashua) and north-central (Kanawha) Iowa, respectively. The experiments were conducted using a replicated split-plot design under conventional tillage. A native prairie was sampled to provide a reference. Although corn yields increased with N additions, N fertilization increased SOC stocks (0-15 cm) only in the CC system at one site. Evaluated over the whole profile (0-100 cm) the effect was not significant. Considering the C cost for N fertilizer production, N fertilization generally had a net negative effect on C sequestration. Soil pH and available P tended to decrease with increasing levels of N fertilization in the surface soils (0-15 cm) for both sites. Crop rotations that included alfalfa had the highest SOC stocks, whereas the CS system generally had the lowest SOC stocks. Concentrations of SOC increased significantly from 1990 to 2002 in only two (fertilized CC and COAA at Kanawha) of the nine systems for which historical data were available. Indices of soil quality such as total N, particulate organic carbon, and microbial biomass were influenced by cropping system, with CS less than CC less than CCOA. The results support carbon credits for rotations that include alfalfa but not for high levels of N fertilization.
Lee, Juhwan (University of
California-Davis, Dept. of Plant Sciences, Davis, CA, 95616; Phone:
530-754-7537; Email: ecolee@ucdavis.edu)
Spatial Variability of Greenhouse Gas Emissions and Their Controlling Factors in an Agricultural Landscape
J. Lee*, C. Van Kessel, D.E. Rolston, J. Six, A.P. King
We determined the singular and interactive effects of soil texture, soil moisture and tillage on the flux of CO2, N2O, and CH4 in order to understand differences in greenhouse gas (GHG) emissions between minimum and standard tillage systems (MT versus ST) at 28 ha field scale. We also quantified the spatial variability of controlling factors on GHG emissions across a farmer’s fields. In 2004, 40 soil cores were taken to a depth of 0-15 cm at regular spatial intervals along two 360-m transects which represented a range of variation in soil texture and moisture. The cores were incubated at 25°C at field moist state for 10 days, and then were wetted to 60% of water holding capacity (WHC) and incubated again for additional 10 days. At field moist state, the global warming potential (GWP) was, on average, greater in the ST than MT soil cores, and CO2 production rates were greatest contributor to the GWP of both the ST and MT soils. However, spatial variability of GHG emissions was large at the field scale, masking tillage-induced differences in the emissions. Upon wetting the soil cores to 60% WHC, both CO2 production rates and N2O emission rates drastically increased, but more in the MT than ST cores. Compared to the ST soils, the MT soils with low clay content lost more C and N in the form of GHG as moisture content increased. Most of the spatial variability is primarily explained by differences in tillage and soil texture (e.g., clay content) and to a lesser degree by differences in soil C and N content as well as moisture, indicating an interaction between tillage, soil texture, and moisture content in determining GHG emissions. Microbial biomass, mineral N, and dissolved organic C were also key controlling factors for N2O emission rates.
Lehmann, Johannes (Cornell University, 909 Bradfield Hall, Ithaca, NY, 14853, Phone: 607-254-1236; Fax: 607-254-1236; Email: CL273@cornell.edu)
J. Lehmann*, J. Gaunt, M. Rondon
Options to increase C stores in soil are limited under natural vegetation and virtually absent in agricultural systems, although soil C represents an important pool of C on a global scale. This study explores the potential to increase soil C stocks through management of bio-char (biomass-derived black C). Inspired by remnants of anthropogenic soil manipulation in Amazonia originating from pre-Colombian times, bio-char management was found to significantly increase crop productivity and decrease leaching losses of nutrients in an otherwise infertile soilscape. Bio-char sequestration provides an opportunity to exploit natural C stabilization mechanisms since bio-char is a highly stable form of organic matter that has shown to exhibit greater radiocarbon ages than the oldest organic matter fractions in soil. At the same time, bio-char is present in most soils in measurable quantities of up to 40% of organic C and therefore does not constitute an alien substance. Its primary incentive for application is increasing crop yields by up to 220% and decreasing nutrient losses by leaching. The production of bio-char can be integrated in various land-based production systems but must not compromise ecosystem services. Changing slash-and-burn to slash-and-char systems have the potential to sequester 0.2 Pg C yr-1 globally, and agricultural wastes add an additional 0.2 Pg C yr-1. Renewable fuels are becoming a viable alternative to fossil fuel and gasification of biomass and its partial use for bio-char production have proven to yield 48% bio-char of the added C while still producing 68% of the energy that would be produced under complete combustion. With an estimate of 180-310 EJ yr-1 of renewable energy in 2100, 9.5 Pg C yr-1 can be stored in soils annually. A combination of feasible approaches could sequester 0.6 Pg C yr-1 already today. At the end of this century, up to 10 Pg C yr-1 could be drawn from the atmosphere, helping to offset anthropogenic emissions that today amount to 5.4 Pg C yr-1.
Li, Changsheng (University of New Hampshire, Complex Systems Research Center, Durham, NH, 03824; Phone: 603-862-1771; Fax: 603-862-0188; Email: changsheng.li@unh.edu)
Assessing Alternatives for Mitigating Net Greenhouse Gas Emissions and Increasing Yields from Rice Production in China Over the Next 20 Years
C.
Li*, W. Salas, B. DeAngelo, S. Rose
Mitigation assessment of
greenhouse gas (GHG) emissions from rice paddy production has typically been
based on a limited series of field studies. However, extrapolating the GHG
mitigation potential to watershed, province and national scales, while
capturing heterogeneous conditions, requires the use of spatially explicit
process models, like the DeNitrification and DeComposition (DNDC) model. DNDC is a unique soil biogeochemical model
that simulates aerobic and anaerobic soil conditions, estimates crop yields
based on a crop physiology-phenology model, and assesses the net effect of
alternative management (mitigation strategies) on short- and long-term soil
organic carbon (SOC) dynamics and emissions of N2O, NO, CH4,
and NH3 from both upland and wetland agricultural ecosystems. This paper quantifies the effect on net GHG
emissions and rice yields for several mitigation alternatives, including
changing water management, fertilizer practices, and utilization of rice
straw. For each mitigation scenario, we
ran DNDC for rice-involved cropping systems in China’s ~2500 counties over a
21-year period. Besides mid-season
drainage, which has been widely adopted in China and was incorporated to
various degrees in the baseline, shallow flooding (also known as marginal
flooding) and upland rice scenarios significantly reduced national CH4
emissions since the two practices universally depressed CH4 fluxes
across climate zones, soil types and crop rotation regimes. Applications of
ammonium sulfate and off-season straw only slightly decreased national CH4
emissions, although there were significant impacts under certain
climate/soil/management conditions. All of the alternative practices except
off-season straw amendment reduced national N2O emissions. The N2O
reductions were caused by elevation of soil redox potential due to the
practices of shallow flooding and upland rice as well as by alteration of soil
N dynamics by applying sulfate fertilizer. The rice paddies in China will be a
carbon sink in the coming 20 years, although the sequestration rates vary
inter-annually due to the variation of predicted crop residue incorporation
rate and soil organic matter storage level.
Based on the net effects on CH4, N2O and CO2,
the order of GHG mitigation effectiveness is upland rice greater than shallow
flooding greater than ammonium sulfate greater than off-season straw
amendment. The order is not the same if
only individual GHGs are considered.
However, use of upland rice decreases yields relative to the baseline;
the other mitigation options increase yields.
DNDC’s GHG and yield results can be used as inputs for other analyses
and models to assess the costs, potential market effects and adoption
feasibility of the mitigation options.
Liebig, Mark (USDA-ARS, PO Box 459, Mandan, ND, 58554; Phone: 701-667-3079; Fax: 701-667-3054; Email: liebigm@mandan.ars.usda.gov)
M. A. Liebig*, S. L. Kronberg, J. R. Gross, J. D. Hanson, A. B. Frank, R. L. Phillips
Grazing management systems affect agroecosystem sustainability through impacts on soil condition. We investigated the effects of long-term (over 70 yr) grazing on soil properties and N2O emission within a moderately-grazed pasture (MGP), heavily-grazed pasture (HGP), and a fertilized crested wheatgrass (Agropyron desertorum (Fisch. ex. Link) Schult.) pasture (FCWGP) near Mandan, ND. Grazing-induced changes in species composition and N fertilizer application contributed to differences in soil properties and N2O emission among pastures. Soil organic C (SOC) was 5.7 Mg ha-1 greater in FCWGP and HGP than MGP at 0 to 5 cm, whereas HGP had 2.4 Mg ha-1 more SOC than FCWGP and MGP at 5 to 10 cm. At 30 to 60 cm, SOC in FCWGP was 4.0 and 7.5 Mg ha-1 greater than in HGP and MGP, respectively. Particulate organic matter (POM) C and N in the surface 5 cm of FCWGP were three- and five-fold greater, respectively, than in HGP and MGP. Acidification from N fertilization in FCWGP decreased soil pH and exchangeable Ca and Mg compared to HGP and MGP in the surface 5 cm. Annual nitrous oxide emission was over three-fold greater in FCWGP compared to HGP and MGP, and was positively associated with POM-C across all pastures (r=0.92; P=0.0001). Results from this study suggest fertilized crested wheatgrass enhances deep storage of SOC, but contributes to surface acidification and greater N2O emission relative to native vegetation pastures in the northern Great Plains.
Lilleskov, Erik (USDA-FS-NCRS, Forestry Sciences Laboratory, 410 MacInnes Dr., Houghton, MI, 49931; Phone: 906-482-6303 ext 18; Fax: 906-482-6355; Email: elilleskov@fs.fed.us)
The “Carbon Cascade” into Forest Soils: BioticControl Points, With a Focus on Mycorrhizal Fungi
E.A. Lilleskov*, E.A. Hobbie, A.L. Friend
Carbon (C) fixed by plants travels through complex biogeochemical pathways that determine whether it will be rapidly respired or stored in more long-lived pools. We review known and hypothetical biotic control points along the belowground portion of this “carbon cascade” that might be regulated by human activities, focusing in particular on the role of mycorrhizal fungi. Mycorrhizal fungi are important belowground sinks for net primary production. By manipulating tree species and genotypes, altering site fertility, and changing atmospheric chemistry, humans are almost certainly affecting mycorrhizal biomass, production and inputs to soil C in most of the world’s forests, yet our understanding of these effects are at present rudimentary. Numerous challenges exist in characterizing pools and fluxes of mycorrhizal C in the field. Current methods being used to overcome some of these challenges include in-growth cores, stable and radioisotope analyses, and minirhizotron observations. Estimates of mycorrhizal fungal biomass in soil range widely, with larger biomass estimates for ectomycorrhizal fungi than arbuscular mycorrhizal fungi. Estimates of the portion of net primary production allocated to mycorrhizal fungi range from 3 to 20%, and may scale with belowground carbon allocation. However, the importance of mycorrhizal fungal production to soil C formation is poorly understood. Glomalin (a glycoprotein produced by arbuscular mycorrhizal fungi) and chitin (a fungal cell wall constituent) are two mycorrhizal fungal products whose contribution to soil organic C is being explored, with a particular emphasis on the importance of glomalin. Many other compounds produced by fungi could be important contributors to soil C, including other glycoproteins, mannoproteins, extracellular enzymes, glucans, hydrophobins, and melanins. Further characterization of the production and fate of mycorrhizal fungal biomass is necessary before we can fully assess the role that different fungal associations have in the soil “carbon cascade.”
Lippke, Bruce (University of Washington, 2600 Fairview Ave. E. #7, Seattle, WA, 98102; Phone: 206-543-8684; Fax: 206-685-0790; Email: blippke@u.washington.edu)
B.R. Lippke*, J. Comnick
The Consortium for Research on Renewable Industrial Materials (CORRIM) released a Life Cycle Inventory and Assessment study on wood demonstrating that for the Pacific Northwest, while longer forest management rotations increase the carbon stored in the forest, the corresponding reduction in carbon stored in long-lived products and the displacement of wood by fossil intensive products like steel or concrete, results in an overall reduction in carbon as rotation ages are increased. As a consequence, policies that give credit only to carbon stored in the forest may be counterproductive to their intent. It also raises interesting questions for the overly dense stands in the Inland-west that are threatened by fire but for which the product uses may be short lived. Management treatments are shown to reduce the fire risk and store more carbon when compared to a fire but uncertainty on the timing of fire must be considered in estimating total carbon storage. Methods are developed to demonstrate a likely path for carbon stored by incorporating both the probability of fire and the useful life of the products produced. The probability of fire on high risk stands would appear to be sufficient to justify thinning treatments while also contributing to carbon storage so long as a substantial portion of the product is allocated to long lived uses like housing construction
Litynski. John (U.S. DOE, National Energy Technology Laboratory, PO Box 88, Morgantown, WV, 26505, Phone: 304-285-1339; Fax: 304-285-4638; Email: John.Litynski@netl.doe.gov)
DOE’s Regional Carbon Sequestration Partnerships Initiative: Developing Infrastructure and Validating Carbon Sequestration Technologies
J. Litynski*, S. Klara
Phase I of the Department of Energy's (DOE) Regional Carbon
Sequestration Partnership (RCSP) program began in September of 2003. The
partnerships consist of 216 organizations in 40 States, 4 Canadian Provinces,
and 3 Indian Nations. Six of the Seven
Phase I Partnerships are assessing the potential of terrestrial sequestration
to mitigate carbon dioxide emissions emitted in their regions. Since the programs inception, the
partnerships have been working on several activities designed to create the
knowledge base and infrastructure for the selection of, and potential
small-scale field validation tests during Phase II. During the first year of
the program, the partnerships primary activities have focused on data
collection and analysis. Partnerships are researching emissions data on point,
industrial, and agricultural sources of C02 and other greenhouse
gases; potential geologic and terrestrial sinks; and existing and necessary
transportation infrastructure in their regions. The data is being stored in
regional databases and geographic information systems (GIS). Analysis of this
data is being conducted with decision support tools that will be used to
identify the most promising opportunities for sequestration in each region.
They are identifying modeling and measurement technologies to for future
accounting and monitoring networks for sequestration projects. Partnerships
have also been conducting public outreach and education activities. DOE
recognizes that terrestrial sequestration will play an important role in each
regions portfolio to mitigate CO2 emissions. The DOE's intent has
been to leverage terrestrial sequestration R&D funded by other federal
agencies to implement small-scale field demonstration projects. After assessing
the regions sinks and implementing several validation projects, the
partnerships will have rigorous project implementation protocols that could
satisfy future carbon markets and the DOE EIA 1605B voluntary guidelines. For
terrestrial sequestration activities, the first year has been dedicated to
collecting data and developing regional GIS that will determine the regions
potential to sequester carbon in various sinks as well as identify promising
opportunities for small-scale validation tests. The partnerships geographic
area includes 96% of the total land mass and 98.5% of the agricultural land in
the United States. The regional
partnership are collecting data from national data bases such as the 1978
National Resources Inventory (NRI); Major Land Resource Areas (MLRA); State
Soil Geographic (STATSGO) Data Base for the Conterminous United States; 1992
Land Use Land Cover data (LULC); MODIS Net Primary Production data; and
regional meteorological data from the National Climatic Data Center. The
partnerships are also working with state and county offices to add to and
refine these data sets to assess the sequestration potential for forests,
agricultural lands, wetlands, and grazing lands. The solicitation for Phase II
of the Regional Carbon Sequestration Partnerships initiative was released on
December 14, 2004. The solicitation will
provide up to $100 million over 4 years in federal funds for partnerships of
state agencies, universities, private companies, and national laboratories that
will field test and validate promising carbon sequestration technologies, both
geologic and terrestrial.
Liu, Shuguang (SAIC, USGS
National Center for EROS, Sioux Falls, SD, 57198; Phone: 605-594-6168; Email:
sliu@usgs.gov)
Spatial and Temporal Patterns of the Contemporary Carbon
Sources and Sinks in the Ridge and Valley Ecoregion of the
S. Liu*, T.R. Loveland
Quantification of the magnitude, geographic locations, and identifying the major driving forces of the terrestrial carbon sources and sinks are among the major goals of the North American Carbon Program. As part of a project that is designed to quantify the spatial and temporal distributions of the terrestrial carbon sources and sinks in the conterminous United States since 1973, we simulated the carbon dynamics in vegetation and soils in the Ridge and Valley ecoregion of the United States using the General Ensemble Biogeochemical Modeling System (GEMS). Land cover change information was derived from Landsat data acquired in 1973, 1980, 1986, 1992, and 2000 within 40 randomly located 10-km by 10-km sample blocks. Results indicate that urban and forest areas have been increasing, whereas agricultural land has been decreasing since 1973. Forest clear-cutting activity has intensified from 1973 to 2000. Overall, the Ridge and Valley ecoregion has been acting as a carbon sink since 1973. However, the sink strength has declined continuously during the study period owing to forest aging in the northern part of the ecoregion and increased forest clear-cutting activities in the south. Land cover and land use change and climate interannual variability were the primary drivers that determined the spatial and temporal variability of carbon sources and sinks. The relative contributions to the sink from soil organic carbon and harvested materials have increased over time, implying that these components deserve more study in the future
Liu, Xue (George Mason University, MS 5C3, Center for Earth Observing and Space Research, Fairfax, VA, 22030-4444; Phone: 703-993-4045; Email: xliu4@gmu.edu)
Changes of Carbon Sink in Terrestrial Vegetation?
X. Liu*, M. Kafatos
It has been evidenced that the Earth’s terrestrial biosphere, particularly the forests in the Northern Hemisphere, is responsible at least partially for the “missing” carbon sink in the global carbon cycle system. However, how this terrestrial sink will change over time with changing climate and atmospheric CO2 concentrations is unsolved. Undoubtedly, understanding the dynamics of this terrestrial sink is of critical importance to global carbon cycle modeling, future projections of atmospheric CO2 concentration in turn climate change, and decision-making regarding terrestrial carbon sequestration. While in situ flux measurements can provide high temporal resolution analysis and insights to involving processes, it is difficult to extrapolate to large spatial scales. At the continental to global scales, usage of satellite remote sensing data is inevitable. We, in this paper, present results from our preliminary study on this problem using satellite remote sensing data. Based on the 20 years time series of normalized difference vegetation index (NDVI) produced by NOAA AVHRR system during its continuous land observing missions from 1981 to 2001, global land cover classification, and the strong correlation between NDVI and NPP, the changes of carbon sink in the terrestrial vegetation have been analyzed, including the trends and strengths. In addition, the causes to these changes have also been analyzed with regarding to climate and atmospheric CO2 concentration variations.
Liu, Yongqiang (USDA Forest Service, 320 Green Street, Athens, GA, 30602; Phone: 706-559-4240; Email: yliu@fs.fed.us)
Y. Liu*, J. Stanturf, H. Tian, J. Qu
Wildfires can contribute to regional carbon cycle and climate change by releasing a large amount of CO2 into the atmosphere. Climate change, on the other hand, can affect fire emissions by modifying the environmental conditions for fire ignition and spread. This study seeks to understand the role of wildfires in the United States in atmospheric carbon cycle and the possible disturbance due to global warming. Total emissions of CO2 from wildfires are first estimated using a set of historical fire data from the USDA Forest Service and other federal agencies. The impacts of the global warming on fire emissions are then assessed based on their relationships with temperature and precipitation, and the projected climate change. The results show an average of annual CO2 emissions on the order of 10-1 petagrams of carbon from wildfires. Large interannual variability is found in the fire emissions during the past two decades. High temperature is the most conducive atmospheric condition for strong wildfire emissions in most U.S. regions. Dry weather also contributes to strong emissions. The model-projected U.S. climate change in response to the greenhouse effect is expected to have a major impact on wildland fires and, therefore, the related CO2 emissions. The changes in temperature and rainfall would play opposite roles by increasing and decreasing the emissions, respectively. The change in temperature, however, is much more important during the wildfire season in the western U.S. It is estimated that the magnitude of the nationwide emissions would be nearly doubled by the mid-21st century.
Lokupitiya, Erandathie
(Colorado State University, Natural Resource Ecology Laboratory, Fort Collins,
CO, 80523; Phone: 970-491-1604; Fax: 970-491-1965; Email: elokupit@nrel.colostate.edu)
Inventorying Agricultural Soil Greenhouse Gas Emissions: Methods Used by Annex 1 Countries
E. Lokupitiya*, K. Paustian
Under the UN Framework Convention on Climate Change, member countries are required to prepare and submit national greenhouse gas (GHG) inventories, together with information on the methods used in estimating GHG emissions. Agricultural soils have been identified as a major source category under the Agriculture sector. With regard to the methodology, inventory methods for soils are relatively more complex than for many other emission sources, and inventory estimates for soils have been implemented only to varying degrees among member countries. Currently, the default methodology formulated by IPCC has been used by majority of the member countries, but several Annex1 countries have developed more advanced, country-specific methods. This analysis summarizes and evaluates the methods used by Annex 1 countries in estimating CO2 and N2O emissions in agricultural soils.
Lynne, Gary (University of
Nebraska, Dept. of Agricultural Economics, Lincoln, NE, 68583-0922; Phone:
402-472-8281; Email: glynne@neb.rr.com)
C.
Kruse, J. Sautter, G. Lynne*
Farmers who use technologies and practices to enhance the amount of carbon sequestered in the soil could help to reduce the threat posed by global warming. Environmentally conscious crop production focused on sequestering more carbon, however, may not be motivated by profit maximizing goals alone. It is plausible to posit that farmers may also identify with, and possibly be in conflict with, the shared interest in reducing the effects of global warming. If reducing these effects is a shared interest, sequestration technologies and practices may be adopted even if some profit has to be sacrificed in the process. If not, the financial incentive may have to be even greater than normally expected. This paper contends that the act of using technologies and farming practices that sequester more carbon directly contributes to satisfying joint and non-separable private (self) and public (other) interest tendencies in the farmer decision making process. It is suggest these two interests may inherently be in conflict within each individual, and between farmers and others within the larger community of interests. The metaeconomic, behavioral-economics approach (Lynne, 1999, 2002; Hayes and Lynne, 2004) of this study suggests that farmers have a kind of non-separable, joint preference structure that includes both the egoistic-hedonistic pursuit of profit and the empathetic-altruistic pursuit of a shared public (other) interest, with both interests arising within the self. Results of tobit regression modeling show that farmers’ decisions concerning how much of the carbon sequestering technology and practices to use are based on an interaction and resolution of the conflict between self-interest and other-interest. This effect is ameliorated through preferences for control and the influence of others over how the interests are integrated and balanced. The other-interest and control/influence variables add substantive and robust explanatory power to the standard economic model that would seek to explain this behavior only with financial variables (e.g., price, technology cost, debt-load). The results suggest, instead, that it is quite likely that farmers seek both interests, jointly, and perhaps two kinds of utility rather than the mono-utility based pursuit of only a self-interested profit. Substantive contributions by farmers to solving the global warming problem depend on such a joint pursuit, as the conflict in interests is resolved. Agricultural policy, and carbon sequestration related policy in particular, needs to recognize this joint pursuit of interests, and focus on finding ways to bring about the complementarity that is possible across these interests. Hayes, W.M. and G. D. Lynne. “Towards a Centerpiece for Ecological Economics.” Ecol. Econ. 49,3 (July, 2004): 287-301. Lynne, G. D. “Divided Self Models of the Socioeconomic Person: The Metaeconomics Approach.” J. Socio-Economics 28, 3 (1999): 267-288. Lynne, G.D. “Agricultural Industrialization: A Metaeconomics Look at the Metaphors by Which We Live.” Rev. Agri. Econ. 24,2 (2002): 410-427.
Machado, Stephen (Oregon
State University, CBARC, Box 370, Pendleton, OR, 97801; Phone: 541-278-4416;
Fax: 541-278-4188; Email: stephen.machado@oregonstate.edu)
S. Machado*, S. Petrie, K. Rhinhart
Soil carbon (C) is essential for sustaining crop productivity. In agricultural lands, carbon (C) sequestration is directly influenced by cropping systems. Tillage, crop rotations, and cropping intensity influence the rate at which C is added and removed. Cropping systems that result in the C gain and sustained soil productivity should be developed. Determinations of sustainability, however, take many years and require long term experimentation. The Columbia Basin Agricultural Research Center (CBARC), near Pendleton, Oregon, is home to the oldest agricultural experiments in the Pacific Northwest (PNW) with some of the experiments dating back to 1931. These experiments have different tillage, cropping intensity, and crop rotation treatments that can shed light on soil productivity and sustainability. To determine the effect of these cropping systems on sustainability, soil samples were taken at 0-10, 10-20, 20-30, and 30-40-cm soil depth profile from the grass pasture (GP) that has not been cultivated since 1931, fertilized (100 kg N ha-1) and unfertilized plots of the continuous conventional tillage winter wheat (CTWW) monoculture initiated in 1931, the conventional tillage wheat/fallow (CTWF) experiment initiated before 1984, and from the fertilized (112 kg N ha-1) and unfertilized plots of continuous no-till winter wheat (NTWW) experiment initiated in 1997. The samples were analyzed for soil organic matter (SOM) at AgriCheck (Umatilla, OR), a commercial soil testing laboratory. Soil organic C (SOC) was estimated by dividing % soil organic matter by 1.724. In the 0-10 cm soil depth profile, uncultivated plots had higher SOC than tilled plots. The highest level of SOC (3.0%) was observed in GP, followed by fertilized NTWW (2.0%), unfertilized NTWW (1.93%), fertilized CTWW (1.86%), unfertilized CTWW (1.78%), and CTF (1.47%) in the 0-10-cm soil depth profile. Fertilized CTWW had the highest SOC (2.07%) followed by GP (1.80%), unfertilized CTWW (1.73%), the NT plots (1.36-1.41%) and lastly the CTF (1.09%) in the 10-20-cm soil depth profile. The trend was similar for the 30- and 40-cm depth profiles. Results indicate that NT cropping systems sequestered more C in the top soil than tillage treatments. More C was stored at lower depths in continuous cropping systems under tillage. Fertilization increased SOC by an average of 0.34%. Among tillage systems, continuous cropping significantly increased SOC compared to fallow at all soil depths. To sustain soil productivity, therefore, fallow should be replaced by continuous cropping and NT. Practicing NT for only 6 years resulted in significantly higher SOC at all soil depths than CTF for more than 24 years. Based on these results, it is recommended to intensify crop production and practice NT to sustain soil productivity.
Magrini, Kim (National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO, 80401; Phone: 303-384-7706; Fax: 303-384-6363; Email: kim_magrini@nrel.gov)
Rapid Identification and Quantification of Soil Organic Carbon Forms Using Pyrolysis Molecular Beam Mass Spectrometry
K.A. Magrini*
A critical need exists to better understand both the amount of soil organic matter (SOM) as a result of land use and management practices and its chemical (and structural/molecular) composition. Rapid quantitative analysis of soil carbon and SOM is required for assessing and monitoring managed agricultural and forest soils to establish carbon sequestration baselines, uptake, and retention. This need is not currently being met in carbon sequestration studies and instrumentation and methodologies must be developed so that SOM inventories can be measured and quantitated in the terrestrial biosphere. We are using analytical pyrolysis coupled with molecular beam mass spectrometry (py-MBMS) and multivariate statistical analysis to rapidly analyze (5-minutes) and quantify SOM in well-characterized agricultural soils (from eleven Midwestern states) provided by the United States Department of Agriculture (USDA) National Soils Laboratory in Lincoln, NE. Multivariate statistical analysis of the mass spectral and characterization data demonstrate that carbon contained in the particulate organic matter (POM), mineral (Cmin), and microbial biomass (SMBC) soil fractions can be measured as a metric expressed as mg-g fraction/g soil. Figure 1 shows principal component analysis of mass spectra from the 0-5 cm depth increment of prairie soils under varied management practice. We have used this technique to assess impacts on SOM accumulation in agricultural soils under the USDA’s Conservation Reserve Program (CRP) management and unambiguously show that eighteen-year old CRP soils have not yet reached native SOM or total carbon content. Additional work with forest soils subjected to periodic disturbance shows that soil chemistry, depths, and location can easily be distinguished based on mass spectral signatures. We are using these results to develop data based models to predict soil carbon content in SMBC, POM, and Cmin soil fractions that can then be used in assessing carbon sequestration pathways and progress
Majdi, Hooshang (Swedish University of Agricultural Sciences, P. O. Box 7072, Uppsala, SE-75007, SWEDEN; Phone: 004618672428; Fax: 004618673430; Email: Hooshang.Majdi@eom.slu.se)
Carbon Pools and Dynamics in Mineral Soil Horizons of
Boreal Forests Along a Climatic Gradient in
H. Majdi*, D. Berggren, M. Olsson, G. Agren
The carbon stocks as a function of carbon fluxes in mineral soil horizons (A, E and B) of three Spodosols were studied along a S-N climatic gradient in Norway spruce stands in Sweden (Asa, Knottåsen and Flakaliden) during 2001-2003. Fine root litter production and dissolved organic carbon (DOC) were measured to investigate carbon fluxes. Minirhizotrons were used to estimate fine root longevity (yr) and soil cores to estimate standing biomass. Annual fine root litter production (g m-2 yr -1) was calculated by dividing fine root standing biomass by fine root turnover (the inverse of root longevity). DOC concentrations were measured weekly in bulk deposition, throughfall and soil solutions in polyethylene funnels. Annual DOC fluxes (g m-2 ; bulk deposition and throughfall) was calculated by multiplying measured DOC concentrations with measured water volumes and DOC for soil solutions by multiplying measured DOC concentrations with simulated water fluxes using the COUP model. The steady state carbon stocks were assessed with the Q model based on the C influx data and a continuous description of soil fine-root carbon and DOC qualities during the decomposition process Annual fine root litter production in mineral soil horizons (0-40 cm) was 65, 50 and 47 g m-2 in the Asa, Knottåsen and Flakaliden stands, respectively. The corresponding values for DOC retention in the mineral soil was 24, 9.4 and 11 g m-2. The steady state stocks predicted by Q model were reasonable consistent with measured data, thus explaining larger carbon stocks in a warmer climate as a function of more root litter and DOC. It is concluded that root litter production and DOC retention are contributing about equally to the C build-up in the mineral soil, when accounting for the higher recalcitrance of DOC compared to root litter.
Martens, Dean (USDA-ARS, Southwest Watershed Research Center, 2000 E. Allen, Tucson, AZ, 85719; Phone: 520 670-6380 x156; Fax: 520 670-5550; Email: dmartens@tucson.ars.ag.gov)
D. Martens*, J.E.T. McLain
In semiarid soils, variability in seasonal soil moisture (SM) and temperature (T) can alter ecosystem/atmosphere exchange of CO2 and the trace gases N2O and CH4 potentially acting as a negative or a positive feedback to global warming. The impact of SM inputs (warm summer monsoon vs. cool winter rain) on fluxes of these gases was monitored in three vegetation zones from July 2002 – September 2003 in southeastern Arizona. The soil C content (0-5 cm) in the vegetation zones ranged from 5.2 g C in the bare site, 13.4 g C in the sacaton (Sporobolus wrightii) site to 30 g organic C kg-1 soil under established mesquite (Prosopis velutina). Carbon dioxide and N2O emissions during the 15 month study were highly dependent on available SM and T. During heavy rains of the 2002 monsoon (81% of 2002 rainfall), large differences in soil C content did not correlate with variations in CO2 production, as efflux from the three sites averaged 124.4 ± 1.9 g CO2 m-2. During the fall through spring period, CO2 production efflux for the three sites averaged 93.5 ± 14.7 g m-2. In 2003, limited monsoon rain (59% of 2003 rainfall) CO2 emissions were reduced (compared with 2002) by 19%, 40% and 30% in the mesquite, open, and sacaton sites, respectively to 88.4± 16.3 g m-2 (average 29% reduction). Isotopic analysis of CO2 respired showed that the majority of C respired (50 to 98%) reflected the isotopic signal of the site vegetation. Nitrous oxide emissions during the 2002 monsoon season averaged 21.1 ± 13.4, 2.1 ± 4.4, and 3.9 ± 5.2 ug N2O m-2 h-1 in the mesquite, open, and sacaton sites for an average N2O monsoon flux of 16.2 mg m-2. During the fall through spring period, N2O production efflux for the three sites averaged 33.7 ± 18.6 mg m-2. Limited rainfall during the 2003 monsoon reduced N2O emissions by 47% in the mesquite, but N2O fluxes increased in the sacaton (5%) and open (55%) compared with 2002 for an average monsoon emission of 12.3 ± 6.7 mg m-1> (24% reduction). Following a dry winter and spring 2002 (15 mm rain), premonsoon CH4 consumption in the three vegetation zones was close to zero, but following monsoon precipitation (238 mm rain), the CH4 sink averaged 45.4 ± 15.8 mg m-2. From October through April 2003 across all sites the CH4 sink averaged 146.1 ± 23.6 mg m-2. Methane oxidation was a subsurface process as oxidation rates were measured at the 5-50 cm depth in laboratory incubations suggesting that as the soil surface dried, CH4 oxidation activity shifted deeper in the sandy soils, thus allowing for high net oxidation flux rates while the surface soil was extremely dry. This study measured ecosystem greenhouse gas potential (GHGP) that averaged 128.5 ± 23.6 g m-2 with the 2002 monsoon with a post monsoon GHGP of 100.1 ± 19.1 g m-2. A 60% reduction in monsoon precipitation in 2003 reduced GHGP to 91.0 ± 18.1 g m-2 (29% reduction) that suggest predicted shifts in annual precipitation patterns from a majority as summer rain to greater winter precipitation may reduce soil CO2 and N2O emissions while promoting CH4 oxidation rates in semiarid zones of the Southwest, potentially acting as a negative feedback for future global warming.
Martens, Dean (USDA-ARS,
Southwest Watershed Research Center, Tucson, AZ, 85719; Phone: 520-670-6380
x156; Fax: 520-670-5550; Email: dmartens@tucson.ars.ag.gov)
Rapid Loss of Soil Active C Pools Fuel Depletion of Soil C Following Mesquite Removal in Semiarid Grasslands
D.A. Martens*, M. McClaran
Grasslands or savannas are one of the most widespread biomes
on earth, covering about 40% of the terrestrial land surface. The proliferation
of woody plants on grasslands has prompted the deployment of brush management
techniques in attempts to improve grasslands. Recent evidence suggests that
enhanced woody growth results in a major biomass and soil C sink and may
provide financial incentives to promote C sequestration. In semiarid
grasslands, soil C contents are typically greater beneath mesquite trees than
open grasslands, but little is known about the rates of accumulation during
tree growth or depletion following removal. We estimated these rates by
comparing C content of soil and physical fractions (light, POM, MOM, silt and
clay) among three settings: beneath old trees (100 yr, n = 4), 40 yr skeletons
of herbicide-treated old trees (n = 2), and open grasslands (n = 6). All areas had sandy loam soils, and were
between 950-1100 m elevation on the Santa Rita Experimental Range, Tucson AZ. To determine a soil profile C composition
under the different treatments, soil and bulk density samples were taken in
2002 from 0-5, 5-10, 10-30, 30-50 cm depths. From the 0-10 cm soil depth, C
accumulation was greater under the old trees (0.91 kg m-2) compared to the skeletons (0.62
kg m-2) and the
grass sites (0.55 kg m-2). Physical
fractionation with density separation (1.85 g cm-2) found that the active/passive C
ratio was greater under the mesquite (0.86) compared with skeletons (0.64) and
grass (0.69) sites. From the 10-30 cm depth, C accumulation was similar under
the old trees (0.81 kg m-2) compared
to the skeletons (0.81 kg m-2), but
greater than the grass sites (0.73 kg m-2). Determination of active and passive C pools found that the
active/passive ratio was greater under the mesquite (0.29) compared with
skeletons (0.16) and grass (0.26). From the 30-50 cm depth, C content was
similar under the old trees (0.78 kg m-2) compared to the skeletons (0.75 kg m-2) and the grass sites (0.77 kg m-2).
The active/passive ratio was greater under the mesquite (0.18) compared
with stumps (0.09) and grass (0.10). The mesquite sites had a greater soil C
content of 0.31 kg C m-2>
compared with the skeletons and 0.45 kg C m-2 more C than the grass sites in the 50 cm profile, but the
majority of the “sequestered” C was in the litter, light and POM fractions.
Average rates of C accumulation under the mesquite trees were 5 g C m-2 yr-2 (50 cm depth) while average rates
of C loss following removal were 8 g C m-2 yr-2 (50 cm
depth). This rapid rate of decomposition is fueled by the relatively high
proportion of active fraction C in the accumulated C beneath old mesquite
compared to open grasslands. The results suggest that large-scale removal of
mesquite from this ecosystem will result in rapid mineralization of the active
C pools. Thus, potential financial incentives for maintaining woody plants
would provide an alternative to limit large-scale clearing and the rapid C
mineralization, which could act as a positive feedback to climate warming.
Massey, Joseph.H. (Mississippi State University, 117 Dorman Hall, Mail Stop 9555, Mississippi State, MS, 39762; Phone: 662-325-4725; Fax: 662-325-8742; Email: jmassey@pss.msstate.edu)
Reduced Water Use and Methane Emissions from Rice Grown Using Multiple Inlet Plus Intermittent Irrigation
J.H. Massey*, M.C. Smith
By 2020, global rice (Oryza sativa) production must increase ca. 30% above current levels to
meet the increased demands of a growing, more affluent population. Many
rice-producing countries consume all of their rice in-country. In contrast, the
U.S. currently exports ca. 40% of its rice crop. Thus, one might expect that
increased production in the U.S. will play a key role in meeting increased
global demand for rice. To meet this need, however, U.S. rice producers must
address several issues that threaten the long-term sustainability of current
production practices. First among these issues is groundwater depletion, as
current rice production methods require seasonal use of ca. 2.5 acre-feet of
water or >five times that used in producing corn, cotton, or soybeans. The use of groundwater for irrigation
purposes has contributed to aquifer declines averaging ca. 1 ft (Mississippi)
to 3 ft (Arkansas) per year in the Mississippi River delta where >80% of
U.S. rice is grown. Beginning in the mid-1980’s, rice-growing regions in Asia,
particularly China, developed water conservation practices to balance
agricultural, urban, and industrial demands for limited water resources. Water
savings of up to 50% over that of continuously-flooded rice paddies have
occurred in fields using intermittent irrigation where floodwaters are allowed
to naturally subside prior to each flood reestablishment. It is not certain, however, that this same
approach would transfer to much the larger U.S. rice production fields that can
be up to 300 A in size. Concerns surrounding the use of intermittent rice
irrigation in the U.S. include potential negative impacts on pest control,
fertility management, grain quality, and yield. Our on-going project is determining
the feasibility of growing rice using intermittent irrigation in
production-scale fields. We have coupled intermittent flood management with
multiple-inlet flood distribution using plastic poly-pipe so that the cyclical
floods can be quickly reestablished across large rice fields typical of the
Mississippi River delta. Results to date from six field sites (typical size ~
40 A) indicate that water use may be reduced by ca. 30% with no decrease in
rice yield; greater savings are expected as producers become more comfortable
with this approach. If intermittent rice flooding proves to be agronomically
viable, its adoption could also impact another issue facing rice production: Globally, flooded rice culture is a
significant source of methane. As a result, practices that reduce methane
emissions have been sought. Wide-spread adoption of intermittent rice
irrigation has reportedly reduced methane emissions in Asia. Although methane
produced by U.S. rice represents <0.5% anthropogenic sources, reductions in
methane as an indirect benefit of water-saving rice irrigation practices would
still be welcomed. Our preliminary, static-chamber results agree with those of
others that indicate that significant reductions in methane flux (up to 70%)
may occur when rice is grown using intermittent flooding rather than continuous
flooding currently practiced in the U.S.
McCarl, Bruce (Texas A&M University, Department of Agricultural Economics, College Station, TX, 77843; Phone: 979-845-1706; Email: mccarl@tamu.edu)
M. Kim, B.C. McCarl*, B.C.
One major concern regarding land-based carbon sequestration involves the issue of permanence. Sequestration may not last forever and may either be released in the future or require expenditure to maintain the practices that keep it sequestered. In this paper, we investigate the differential value of offsets in the face of impermanent characteristics by forming a price discount that equalizes the effect price per ton between a "perfect offsets" and one possessing some or all of these characteristics. We find this discount to be a function of the future needs to replace offsets (in the face of lease expiration quantity or volatilization (upon activities such as timber harvest) and the magnitude of any needed maintenance costs. We investigate the magnitude of the discounts under alternative agricultural tillage and forest management cases. In those studies we find that permanence discounts in the range of 50% are not uncommon. This means that in the market place an impermanent sequestration offset may only receive payments amounting to 50% of the market carbon price. Furthermore we find that in the face of escalating carbon prices that offsets may prove to be worthless.
McCarty, Gregory (USDA-ARS,
Building 007, Rm 202, BARC-West, Beltsville, MD, 20705; Phone: 301-504-7401;
Fax: 301-504-5048; Email: mccartyg@ba.ars.usda.gov)
G.W. McCarty*, P.C. Doraiswamy, E.R. Hunt, R.S.Yost, M. Doumbia, A.J. Franzluebbers
Agriculture in sub-Saharan Africa is a low-input low-output system for subsistence. Some of these areas are becoming less able to feed the people, because of land degradation and erosion. The aims of this study are to characterize the potential for increasing levels of soil carbon for improving soil quality and carbon sequestration. A combination of high- and low- resolution imagery were used to develop a landuse classification for an area of 64 km2 near Omarobougou, Mali. Field sizes were generally small (less than 1 ha), and the primary cultivation systems are conventional tillage and ridge tillage. Based on land-use classification, climate variables, soil texture, in-situ soil carbon concentrations, and crop growth characteristics, the EPIC-Century model was used to map the current and projected amounts of soil carbon sequestered for the region. The range of yields for maize for the past 6 years (1997-2002) was between 2-6 Mg/ha, millet yields ranged between 0.6-1.1 Mg/ha, and sorghum yields ranged between 2–6 Mg/ha. Year-to-year variations can be attributed to primarily rainfall and availability of fertilizer. Under continuous conventional cultivation with minimal fertilization and no residue management, the soil top layer was continuously lost due to erosion, losing between 1.1 to 1.7 Mg C/ha over 25 years. The model projections suggest that soil erosion is controlled and that soil carbon sequestration is enhanced with a ridge tillage system, because of increased water infiltration which increases production. The combination of modeling with the land use classification was used to calculate that between 40 to 104 Mg C /year may be sequestered for the study area with ridge tillage, increased application of fertilizers, and improved residue management.
McSwiney, Claire (Michigan State University, W.K. Kellogg Biological Station, 3700 East Gull Lane, Hickory Corners, MI, 49060; Phone: 269- 671-2212; Email: cmcswiney@kbs.msu.edu)
Global Warming Impact of Irrigated Continuous Corn Fertilized at Different N Rates
C.P. McSwiney*, G.P. Robertson
In past studies at the W.K. Kellogg Biological Station in southwest Michigan we determined that N2O fluxes measured across a high-resolution N gradient were moderately low (less than 50 g N2O-N ha-1 day-1) up to 101 kg N ha-1 additions (grain yield maximum), after which fluxes increased sharply. In 2003, N, as granular urea, was applied at nine levels from 0-292 kg N ha-1 yr-1 to 8 replicate fields in continuous corn and then incorporated. Four replicates were irrigated to alleviate water stress in the corn crop. From these results we calculated the N rate at which we gained the greatest mitigation potential for the global warming impact (GWI) of these cropping systems by including contributions from all sources of radiative forcing in these systems – fertilizer, fuel, lime, pesticides, soil C change, and trace gas fluxes. We found that by fertilizing at the N level required to maintain maximal yields, we gained a 34% reduction in GWI compared to the N level that is considered best management practice. When crops were grown in a corn-soybean-wheat rotation, there was an additional 66% reduction in GWI. The GWI increases precipitously at N rates that are higher than required to maintain yields, primarily driven by N2O fluxes from the farm field and CO2 produced during N fertilizer manufacture. By using less N fertilizer and maintaining fields in rotation, growers can significantly reduce the GWI of their farming operations.
Michitsch, R. (Soil & Crop Improvement Association of Nova Scotia, 20 Tower Road, Truro, NS, B2N 5E3, Canada; Phone: 902-896-7092; Fax: 902-893-0335 Email: michitrc@gov.ns.ca)
Greenhouse Gas Mitigation Practices and Activities in the Eastern Canadian Agri-Food Sector
R. Michitsch*, D. Burton, R. Gordon, S. Ellsworth
In Eastern Canada, the agri-food sector plays a particular role in the production of greenhouse gases (GHGs) through its varied activities. The reduction of these emissions (as CO2, CH4 and N2O) is actively being investigated by Atlantic Canadian researchers, given Canada’s commitment to reduce such emissions as mandated by adoption of the Kyoto Protocol. The potential to mitigate GHGs from the agri-food sector is achievable through increased farm-level awareness and the adoption of beneficial management practices (BMPs) related to soil, nutrient-management, animal and cropping practices. Sustaining the economic viability of the farm and other environmental benefits beyond GHG mitigation are priorities, to both foster adoption of BMPs and create a sustainable relationship with nature. In 2003, the Canadian federal government established the Greenhouse Gas Mitigation Program (GHGMP). This program is co-ordinate in parts of Eastern Canada by the Soil & Crop Improvement Association of Nova Scotia (SCIANS) under the supervision of the Soil Conservation Council of Canada (SCCC). A producer-based organization, SCIANS functions to support the improvement of soils and crops through the adoption of BMPs, to ensure the competitiveness of the Nova Scotia agri-food industry and to conduct farm-level research for the betterment of the Nova Scotia farming community. Areas of focus for on-farm demonstrations cover the following areas: management of nitrogen fertilization and soil nitrogen testing; reduced tillage systems and technologies; timing of manure application; and manure application techniques. Additional topics encompass manure storage techniques, bio-gas production through the anaerobic digestion of manure, feeding strategies, constructed wetlands and composting systems. Education and outreach are priorities of this demonstration program. Several projects have been in co-operation with other organizations, such as Horticulture Nova Scotia (HortNS), the Atlantic Swine Research Partnership (ASRP), the Eastern Canada Soil and Water Conservation Centre (ECSWCC) and Agriculture and Agri-Food Canada (AAFC). Overall, a network of information sharing has been established, which benefits all stakeholders. This allows for the convenient and timely dissemination of knowledge to Atlantic Canadian producers for both short and long-term mitigation of greenhouse gases.
Mikha, Maysoon (USDA-ARS, 40335 County Road GG, Akron, CO, 80720; Phone: 970-345-2259; Fax: 970-345-2088; Email: maysoon.mikha@ars.usda.gov)
M.M. Mikha*, M.F. Vigil
The predominant cropping system in the Central Great Plains winter wheat summer fallow (W-F) is not sustainable. Losses of soil organic matter (SOM) in the Great Plains are associated with tillage and summer fallow management. Intensive cropping systems with reduced tillage and fallow frequency are management practices that provide more residues and may increase soil C and N content. This study investigated the effect of five different crop rotations on soil total C (TC), total N (TN), and yield. Various cropping intensities comprised of winter wheat (Triticum aestivum L.), corn (Zea mays L.), proso millet (Panicum miliaceum L.), seed pea (Profi pea), and fallow were evaluated and to compared to W-F. The experiment was established in 1990 on a Weld loam (fine, smectitic, mesic aridic Paleustolls). In 2004, soil samples were collected (0-5 and 0-15 cm depths) from the field treatments and evaluated for soil C and N. Fourteen years of continuous cropping improved soil TC compared with NT and CT W-F rotation at 0-15 depth. Soil TC and TN significantly (p less than 0.05) increased with NT W-F compared to CT W-F especially at 0- to 5 cm depth. Continuous cropping such as W-C-M significantly (p less than 0.1) increased soil TC (0-5 cm) compared with NT W-F and W-C-F cropping systems. There was a trend for increased TC for W-C-M-F and W-C-M-P compared with W-F but the increase was not statically significant (p less than 0.1). More than 40% of TC and TN was associated with 0-5 cm depth except for CT W-F were TC and TN represent 35 and 33% of 015 cm, respectively. Wheat grain yield was significantly affected by rotations. Grain yields were significantly greater in NT W-F, W-C-F, and W-C-M-F than in CT W-F and W-C-M. Generally, NT and continuous cropping with reduced fallow improved soil TC at the soil surface (0-5 cm).
Mikhailova, Elena (Clemson University, 261 Lehotsky Hall, Clemson, SC, 29634; Phone: 864-656-3535; Fax: 864-656-3304; Email: eleanam@clemson.edu)
Soil Organic and Inorganic
Carbon Dynamics in Grassland Ecosystems
E.A. Mikhailova*, C.J. Post
Grassland soils play an important role in the global carbon cycle, but their contribution to the soil carbon storage is often underestimated. The objective of this study was to evaluate the soil organic and inorganic carbon storage at depth in the Russian Chernozem (fine-silty, mixed, frigid Pachic Hapludoll) under different management regimes: a native grassland field (not cultivated for at least 300 years), an adjacent 50-year continuous-fallow field, a yearly cut hay field in the V.V. Alekhin Central-Chernozem Biosphere State Reserve in the Kursk region of Russia, and a continuously cropped field in the Experimental Station of the Kursk Institute of Agronomy and Soil Erosion control. Implications of these findings are discussed in terms of global and regional soil organic and inorganic carbon estimates. Soil organic and inorganic carbon dynamics in grassland ecosystems are described in relation to their potential for soil carbon sequestration
Min, Doo-Hong (Michigan State University, Upper Peninsula Experiment Station, PO Box 168, Chatham,, MI, 49816; Phone: 906-439-5114; Email: mind@msu.edu)
Dairy Forage Cropping Best Management Practices: A Comparison of Soil Carbon Sequestration and Greenhouse Gas Fluxes
J.D. DeYoung, R.H. Leep, D.H.Min*, T.S. Dietz
A study was initiated in 2002 located at the Kellogg Biological Station (KBS, Hickory Corners, MI) and the Upper Peninsula Experiment Station (UPES, Chatham, MI). The objective of this study was to provide forage crop producers with information regarding the results of cropping system management decisions on the basis of soil carbon sequestration and greenhouse gas production potentials of different no-till dairy forage production systems. The study was a replicated, randomized complete block design, with no-till dairy-forage cropping system treatments. These include continuous corn, continuous alfalfa, corn-alfalfa rotation, and an alfalfa-orchardgrass mixture. Each cropping system was subjected to two levels of organic matter inputs, either no organic matter input, or organic matter input in the form of composed manure (KBS location), or dairy manure slurry (UPES location). Both forms of organic matter were applied at a rate of 3,360 kg of carbon per hectare. Data collection included forage dry matter yield, forage quality, soil greenhouse gas emissions (carbon dioxide, methane, and nitrous oxide), total soil carbon and nitrogen, particulate organic matter carbon, soil bulk density, and soil nitrate and ammonium nitrogen. Results after 3 years of cropping and organic matter treatments indicate differences in greenhouse gas emissions measured in this experiment were mainly due to soil moisture and temperature changes and only secondarily related to cropping or organic matter treatments. Soil carbon sequestration, was measured as the differences in soil particulate organic matter (POM) levels between cropping and organic matter treatments. At KBS, plots that had compost applied tended to have higher levels of POM in the top 5 cm of soil. However, these differences were not significant. At UPES, the high background levels of soil carbon made detecting any differences in POM difficult, therefore, no differences between treatments were found. There were no measured differences between the cropping or organic matter treatments and soil nitrate, ammonium, or soil bulk density.
Miner, Reid (NCASI, PO Box 13318, Durham, NC, 27709; Phone: 919-941-6407; Fax: 919-941-6401; Email: rminer@ncasi.org)
The 100-Year Method for Corporate Accounting of Carbon Stored in Products-In-Use
R. Miner*
A large amount of carbon removed from the atmosphere by trees is stored in wood and paper products. In 2003, IPCC experts estimated that carbon stocks in products-in-use were growing globally at a rate of 40 Tg/year (million metric tons per year). The U.S. government has estimated that, in 2002, carbon stocks in products-in-use in the United States were increasing at a rate of 16 Tg C/year. With global population and standards of living growing, the amounts of carbon stored in forest products will continue to increase. Clearly, if one wants to correctly characterize the carbon profile of the forest products industry, it is critical to estimate the amounts of carbon stored in products. Methods are available for characterizing carbon storage in products for national greenhouse gas inventories. The methods used for national accounting, however, are not suitable for corporate or value chain accounting. This is partly due to the practical difficulties that companies face in assembling the historical production data and other information required by the methods. In addition, national accounting methods generate results that are heavily influenced by historical data and past practices. As a result, these methods provide little insight into opportunities for improvement. In this presentation, a method is described for corporate and value chain accounting of carbon in forest products that avoids many of the difficulties associated with national accounting methods. The method, which is gaining acceptance by the global forest products industry (as represented by the International Council of Forest and Paper Associations), focuses on the long-term effects of current production on future stocks of carbon sequestered in forest products. It estimates the amount of carbon in products expected to remain in use for at least 100 years and, therefore, the method is called the 100-year method. This presentation will examine the need for the 100-year method and will include a demonstration of the method on a hypothetical but representative forest Products Company. The demonstration will illustrate the use of the method and the importance of carbon in products to the overall carbon profile of a forest products company.
Molodovskaya, Marina (Cornell
University, BEE Department, 76 Riley-Robb, Ithaca, NY, 14853; Phone:
607-339-8644; Email: mm433@cornell.edu)
M.S. Molodovskaya*, O. Singurindy, S.K. Giri, B.K. Richards, T.S. Steehuis
Nitrous oxide emissions from agriculture substantially contribute to the greenhouse effect and total available nitrogen loss. Though many previous studies have investigated N2O emissions from agricultural soils and manure storage facilities, very little is known about the potential for N2O formation and emissions from fresh land-applied dairy manure. Since nitrous oxide is formed as a subproduct of microbial nitrification/denitrification processes, the rate of emissions from fresh manure can be very high due to high total N and C initial content. N2O formation also strongly depends on oxygen availability. The objective of this study was to estimate nitrous oxide emission from fresh dairy manure under different aeration rates. Samples of fresh manure (1.35g dry matter) mixed with distilled water (100 ml) were incubated at 25° C for 15 days and aerated continuously with air at flow rates varied from 5, 45, and 90 mL g-1 min-1. The results have shown significant difference in N2O emissions, with the greatest emission of N2O-N correlating with the greatest airflow rate. The concentrations of other mineralized forms of nitrogen (nitrate, nitrite and ammonium as well as volatile ammonia emissions) were also measured and used to quantify the nitrogen transformations.
Murray,
Brian C. (RTI International,
Hobbs 131, 3040 Cornwallis Road, Research Triangle Park, NC, 27709-2194; Phone:
919-541-6468; Fax: 919-541-6683; Email: bcm@rti.org)
Estimating Leakage from Forest and Agricultural Carbon Sequestration Projects
B.C. Murray*, B.A.
McCarl, B.L. Sohngen,
Leakage is prominent
among the concerns often raised about agriculture, land use change, and
forestry carbon sequestration projects as a GHG mitigation strategy. While there is wide recognition that leakage
should be deducted from the reporting of estimated carbon benefits from a
mitigation project, no consensus yet exists on how to quantify leakage. Leakage
occurs when the actions to reduce GHG emissions for a particular project cause
responses outside the project boundaries that also have GHG consequences. The cause of leakage is a shifting of
economic activity from inside the project boundaries to outside. Therefore
approaches to address leakage must employ economic principles, methods and data
to estimate its potential magnitude.
This presentation builds off of economic analyses the co-authors have
collectively conducted to examine leakage effects from forest and agricultural
carbon programs both domestically in the U.S. and abroad. The work has primarily employed economic
equilibrium models, which re-equilibrate the relevant markets in response to
project or program-induced changes in supply and demand. This market leakage can displace economic
activity and emissions to locations far away from where the project occurs and
is thus difficult to monitor directly.
However, because CO2 emissions are spatially undifferentiated
in terms of their contribution to climate change, even distant leakage matters.
Preliminary findings from the authors’ works suggest that some forest carbon
activities can exhibit large leakage effects depending on the activity itself
(forest protection, afforestation, forest management) and the region where it
is applied. Agricultural soil carbon
sequestration tends to exhibit much less leakage than forest options due to
differences in the extent to which soil carbon management practices affect
productivity. While current estimates of leakage can be useful in determining
rough magnitudes of its probable extent for certain types of forest carbon
sequestration activities, there is likely to be a fair amount of heterogeneity
in actual leakage effects from projects on the ground. The presentation will identify sources of
this heterogeneity and evaluate methods for providing more spatially and
sectorally refined estimates for forestry and agricultural projects.
Nakagawa, Hitoshi (Natl. Inst. Agrobio. Sci. (NIAS), Japan, 2425 Kami-Murata, Hitachi-Ohmiya, Ibaraki, 319-2293, Japan; Phone: +81-295-52-4620; Fax: +81-295-53-1075; Email: ngene@affrc.go.jp)
Biomethanol Production and CO2 Emission Reduction from Forage Grasses, Trees and Residues of Crops
H. Nakagawa*, T. Harada, T. Ichinose, K. Takeno, M. Kobayashi, M. Sakai
With a wide array of potentially renewable energy resources, the concept and proposed benefits evolving from the use of biofuels are inspiring. Recently, a new approach regarding the gasification of biomass by partial oxidation for biomethanol production has been developed and is being evaluated at the 'Norin Green No. 1' test plant in Nagasaki, Japan. To determine a useful protocol for producing biomethanol, various kinds of biomass resources, such as sawdust and bark of Japanese cedar, chipped Japanese larch, salix, cut waste wood from demolition sites, head and foliage of sorghum, grass hay, bran, straw, and husks of rice were evaluated for their potential biofuel-use characteristics. From the analysis, lignocellulosic resources (wood materials) and rice bran are estimated to produce a high methanol yield (55% by weight), whereas rice straw and husks returned 36% and 39%, respectively. Each of these products is a clean material, easily obtained and highly useful for biomethanol production. Developing nations that are interested in constructing a national energy policy focused upon the establishment of a biofuel-based economy. Recycling of byproducts of agricultural and forest industries has been previously shown that they could reduce the demand for fossil fuels and provide for a more ecologically friendly energy resource. Our research suggests that an additional possibility for biomethanol production could be developed through the utilization of cellulosic and lignocellulosic resources as raw materials
Nkongolo, Nsalambi (Lincoln University, Center of Excellence GIS Lab, 820 Chestnut Street, Jefferson City, MO, 65102; Phone: 573-681-5397; Fax: 573-681-5154; Email: nkongolo@lincolnu.edu)
N.V. Nkongolo*, K. Schmidt
Soil thermal properties can affect the production and escape of greenhouse gases from soils to the atmosphere. We studied the relationship between CO2, CH4and N2O fluxes and soil thermal conductivity (K), resistivity (R) and diffusivity (D) in a corn field at Lincoln University Freeman Farm, from May to December 2004. The experimental field was divided into four plots of 0.25ha each. Each plot received the same rate of PK (60-80 lb ha-1) and either 0, 60, 120 or 180 lb ha-1 of N. Six chambers were installed in each plot. Soil samples were collected for analysis of chemical and physical properties. Soil air samples for determinations of CO2, CH4 and N2O were collected from static and vented chambers of 0.30 m long and 0.20 m diameter installed in the field in May 2003 shortly after corn emergence. The sampling process consisted in closing the chamber two ventilation holes with rubber stoppers, putting the chamber greased circular top, vacuuming the chamber then allowing it to be filled with air from soil for 20 minutes, collecting an air sample 4 times with a 50 ml syringe and storing it in a 200 ml Tedlar bag. The chamber top had a middle hole covered by a stopper and used for air vacuuming and sampling. Thermal properties were measured at 0.06 m depth inside each chamber using KD2 Thermal properties meter. Analysis of CO2, CH4 and N2O from air samples was done within two hours of sampling at Dickinson Research Center with a Shimadzu Greenhouse Gas GC-14. Results obtained showed that for the entire field, CO2 fluxes ranged from 5.56 to 395.61 mg C-CO2 m-2 h-1, CH4 uptake from 5.39 to 89.22 ug C-CH4 m-2 h-1 and N2O fluxes from 10.69 to 181.86 ug N-N2O m-2 h-1. Except for CH4 uptake which only correlated with K, CO2 and N2O fluxes were also linearly correlated with R and D with coefficient of correlation (r) ranging from 0.40 to 0.60. In addition, CO2, N2O and CH4 all correlated among themselves with (r) ranging from 0.40 to 0.90. However, when data for each plot was analyzed individually, the linear relationship between gas fluxes and thermal properties was significant only in the plot receiving 180 lb ha-1 N. In this plot, K and R linearly correlated with CH4 and N2O with (r) ranging from 0.80 to 0.90. The correlation between CO2, N2O and CH4 also persisted, but was restricted to only CO2 and N2O in other plots. The results suggest that soil thermal properties may be important controlling factors for greenhouse gas fluxes from soils.
Norton, Urszula (University
of California-Davis, 14571 Stone Lane, Sonora, CA, 95370; Phone: 209-588-2785;
Fax: 209-532-8978; Email: UNorton@ucdavis.edu)
Trace Gas Emissions and Soil C and N Dynamics in Sagebrush and Chaparral Shrublands: Methods, Inventories and Field Experiments
U.Norton*, W.R.Horwath, A.R.Mosier, J.A.Morgan
Sagebrush and chaparral shrubland biomes span a wide
geoclimatic range and cover extensive areas of the United States. Historically, fire played a critical role in
shaping autosuccession of these fire-adapted ecosystems, returning every 30-40
years. However, as these ecosystems
undergo rapid human-induced changes, there is need for better understanding of
how these practices impact ecosystem resiliency, sustainability and ability to
withstand exotic weed invasion. Unlike
many other biomes, C and N dynamics in shrubland ecosystems are poorly
characterized. Specifically, information on the contribution of GHG to the
atmosphere is lacking. For example, the
chaparral biome has one of the largest estimates of nitric oxide and considerable
amounts of nitrous oxide emissions.
Moreover, over a quarter of the estimated global sum of nitric oxide
emissions comes from this biome.
Unfortunately, these estimates are based on a very limited amount of
scientific data and there are no estimates for other greenhouse gases such as
carbon dioxide and methane. We
hypothesize that shrubland ecosystems are very prone to disturbance and
therefore, any restoration practice that would provide ecological benefits
would also improve soil quality and reduce GHG flux to the atmosphere.
Simulating water pulses is an important tool for understanding biogeochemical
processes in semi arid environments. A single summer rainfall event in
sagebrush can contribute as much as 20 or 30 percent of the nitrous oxide in
annual GHG budget estimates. Therefore, the purpose of this on-going research
is to inventory trace gas emissions from sagebrush and chaparral shrublands
ecosystems. Here we present the effects
of water additions on GHG emissions and soil C and N in sagebrush soils, both
canopy and shrub interspace, on sites dominated by either, western wheatgrass,
a native perennial, or cheatgrass, an exotic annual. In August 2003 we simulated a single summer
rainfall event in a Wyoming big sagebrush stand located outside Lander,
WY. We used static chambers deployed on
the soil surface to monitor GHG production, and collected soil samples for
various soil C and N indices at 7 times during 216 hours after wet up. Our
results indicate that long-term cheatgrass establishment affects not only soil
under its own thatch, but also under shrubs within the cheatgrass stand. Overall, soil TN and TOC content on
cheatgrass sites were lower than those of western wheatgrass. Sites dominated by native perennial grasses
(both shrub interspaces and under shrub canopies) were less likely to
contribute as much N gas to the atmosphere as cheatgrass soils upon soil dry
down. These soils were also more
efficient in methane consumption and effective in coupling of N and C
biochemical transformations. Upon water
pulse, cheatgrass soils demonstrated greater carbon dioxide production rates
relative to pre-wet conditions and greater nitrous oxide flux per unit soil
TN. Cheatgrass soils, both interspace
and under shrub canopy, had greater nitrate concentrations that became a
substrate for microbial immobilization or rapid nitrous oxide production.
Cheatgrass soils also showed more rapid initial increase in soil microbial
biomass followed by its immediate mortality, and greater concentrations of soil
dissolved organic C compared to western wheatgrass. In conclusion, sagebrush sites invaded by
cheatgrass were prone to contribute nitrous oxide and methane to the atmosphere
upon summer moisture availability.
Possible mechanisms include greater nitrification potential and faster
turnover of microbial biomass triggered by simultaneous shortages of
microbially available C or N.
Novak, Jeff (USDA-ARS-CPRC, 2611 West Lucas Street, Florence, SC, 29501; Phone: 843-669-5203; Fax: 843-669-6970; Email: novak@florence.ars.usda.gov)
Utilization of Conservation
Tillage Practices to Rebuild Organic Carbon Levels in a Sandy, Coastal Plain
Soil
J.M. Novak*, P.J. Bauer, P.G. Hunt
The pedogenic process in well-drained sandy, Coastal Plain soils has resulted in relatively low soil organic carbon (SOC) levels. In these soils, the predominance of sand-size particles, rapid internal drainage, and high residue oxidation rates causes rapid residue losses and a low build-up of SOC. Cultivation of soils using conventional tillage practices, whereby the residue is mixed into the soils, has increased the decline in SOC levels. Recent research, however, indicates that conservation tillage practices, which minimize residue incorporation, can increase SOC levels, but the increase is limited to the top few cm of soil. Long-term conservation and conventional tillage plots have been managed for 24 years in a sandy, well-drained Coastal Plain soil (Norfolk loamy sand). Crop rotation management in these plots consisted of corn, soybeans, winter wheat, and cotton. After 24 years of tillage management, annual deep coring (0 to 90-cm) within these plots has revealed that the surface SOC levels (0 to 5-cm depth) in soils under conservation tillage were significantly higher (1.33 % SOC, P less than 0.001) compared to soils under conventional tillage (0.84%). Mean SOC levels in lower profile depths were not significantly different (P greater than 0.05) between tillage systems. Efforts currently in progress are to enhance SOC sequestration in lower soil profile depths (below 5 cm) with a cover crop that has a high below ground root biomass (Secale cereale).
Onuchak, Nataliia V. (Tetiiv Institute
of Agroecology and Biotechnology, 15, Stepovoy Street, Kashperivka, Tetiiv area, Kyiv Region, 09812, Ukraine;
Phone: +380 4460 26370;
Fax: +380 4460 26370; Email:
onuchak@ukr.net)
Reaction of Plant Cenosis on Global Change of СО2
Concentration in the Earth Atmosphere
N.V. Onuchak*
The purpose of the present
research is to appraise
tensity and change dynamics of the cenotic interactions in cenosis of
the cereals depending on genotype and level of nitric nutrition
under СО2
enrichment of the atmosphere during the period of plant vegetation. Experiments have
been conducted on the cenosis
model in four-chamber hermetic phytothrone. The
concentration of СО2
was maintained at a natural level of (350 mcl/l) for 24 hours, which is to
be a control in two cameras, whereas in the other two cameras СО2 concentration was doubled
(700 mcl/l), which is to be
experimental. Plants have been grown under optimal conditions of cultivation:
power of radiant flow – 300 Wt/m2 PAR, temperature – 200 C at
day-time and 170 C at night-time, photoperiod – 16 hours, air
humidity – 60 ± 7%. The experiment has been conducted in the soil culture.
Various combinations of mineral salts have been composed in this way in order to create
variants of nitric
nutrition
containing 100,
150, 200, 400 и 600 mg N on 100 g of soil. 2-3 consecutive long experiments were conducted
in each studied sort of cereals including all the plant vegetation. Ontogenetic change appraisal of cenosis
condition has allowed to distinguish period of most intensive interactions in cenosis – cenotic interactions point. System aspiration to the stability
is most expressed in that point which defines maximum amplitude of changes and
allows to use them as description of cenosis condition in the time of study of increased СО2 concentration (700 mcl/l) influence on plant cenosis
structure
depending on genotypes
of which they are made.
In
the present research the role of spring cereals genotype (wheat, barley) on
the low background of nitric nutrition
under СО2
enrichment of the atmosphere has been examined. The
specifics in forming of agrocenosis structure by
cereals have been studied. The researches have shown that rise of СО2
level leads to intensification of plant
growth processes. It has been ascertained that under atmospheric СО2
enrichment it
is observed coming
of the cenotic interactions point in lower biomass of the cenosis in studied genotypes
of both barley
and wheat than under normal СО2 concentration. At the same time cenotic interactions point comes in
an earlier period of growth. It has also been ascertained that under high СО2
level competitive relations in plant cenosis are arising earlier however in majority of
genotypes they are going less hard. Conclusion has been made regarding clear
compensatory mechanism of individual
growth in cereal cenosis depending on СО2 concentration, level of
illumination and genotype competitiveness. In the present research it has also
been studied the role of nitric nutrition
of cereals. The research shows that
under high atmosphere СО2 concentration the efficacy of light use by unit of
assimilative surface of the plant leaf under condition of sufficient level of
nitrogen in the soil is raised. Plant competitiveness is being reduced and the
plants are becoming more tolerant to the conditions of illumination level. Results have shown that rise
of nitric nutrition is a necessary
condition to yield crop increase under rise of СО2 level in
atmosphere as it is necessary sufficient amount of nitrogen in the soil for effective use of СО2
level. As a
result of the conducted researches it has been revealed that level optimization
of nitric nutrition in the soil allows
to lay a base for effective use of СО2 in the atmosphere,
particularly in case of doubling СО2
concentration
and also to increase grain productivity of cultivated cereals.
Ortiz, Roque (Univ. of Murcia, Departamento de Quimica Agricola, Geologia
y Edafo, Murcia, MU, 30100, Spain; Phone: +34-968367443; Email: rortiz@um.es)
Organic Carbon Storage in Surface Soils from Murcia Province, Southeastern Spain in Relation to Land Use and Management
D.M. Carmona, A. Faz, R. Ortiz*
The Convention to Combat Desertification (CCD) is concerned that extensive areas, which have been rendered unsuitable for crop production due to land degradation and reduction in soil carbon stocks. Restoration could contribute to the proper placement of carbon in the geosphere and to food security. Restituting carbon to those lands would also contribute to reducing carbon in the atmosphere. Conservation strategies which sequester carbon include converting marginal lands to compatible land use systems, restoring degraded soils, and adopting best management practices. As a result, the agricultural soils and forestry sectors receive much recent attention because of their potential to store and retain carbon and thus reduce emissions to the atmosphere. The study area is located in Murcia, S.E. Spain. A systematic sampling was carried out for every 3 km, under the LUCDEME Project (Fight against desertification in Mediterranean area) which amounted to a total of 946 soil samples (0 to 25 cm deep) in a total area of 11,317 km2. For this purpose, maps (1:50,000), as well as aerial photographs (1:20,000) were used. The soil samples obtained have the following uses: 1.-Dry trees, whose most representative species are almonds and olive trees, characterised by mostly lacking irrigation and also being found marginally (297 samples); 2.-Citrics, largely lemon and orange tree, appear mostly under localised irrigation (39 samples); 3.-Fruit trees, fundamentally, peach, apricot and plum tree and pip fruit trees, mostly the pear tree. Flood irrigation systems continue being the typical form of irrigation in most cases, although they are visibly replaced by drip irrigation (51 samples); 4. Horticultural species with drip irrigation intensive production high technology; among them the most typical species are broccoli and cauliflower, and onion (25 samples); 5.-The rest of the area destined to growing has been classified as extensive crops such as alfalfa and cereals (137 samples); 6.-Those areas occupied by forest land, with different level of degradation, such as pine (160 samples) and thyme fields (237 samples) are also considered. The main soil types in the area have been classified, according to WRB, as Regosols, Leptosols, Fluvisols, Calcisols, Gypsisols, Solonchaks and Kastanozems. The climate in Murcia province is semiarid Mediterranean, where maximum temperatures coincide with minimum rainfall levels. In relation to organic carbon contents the values were maximum in soils with forest (pine 4.7 kg m-2 and thyme fields and shrubs 4.1 kg m-2). Cultivated soils with fruit trees have the maximum content of carbon (3.5 kg m-2), followed by horticultural species with drip irrigation (3.0 kg m-2), extensive crops (2.6 kg m-2), citrics (2.5 kg m-2), and finally dry trees (2.0 kg m-2). The maximum contents are related to the fact that those soils not only receive supplies from vegetable remains and chemicals fertilizers, but also organic fertilization. As a consequence, this must be the most appropriate management of soils in terms of soil quality and carbon sequestration.
Owensby, Clenton (Kansas State University, Dept. of Agronomy, Manhattan, KS, 66506-5501; Phone: 785-532-7232; Email: owensby@ksu.edu)
C.E. Owensby*, J.M. Ham, L.M. Auen
In order to determine the potential of grasslands to sequester carbon, carbon dioxide fluxes have been measured on tallgrass prairie grazed at ungrazed, moderate, and heavy rates using eddy correlation aerodynamic systems. Flux data are measured continuously and recorded as 30-minute average fluxes. The initial grazing treatments were designed to show the impact of grazing at twice the recommended rate for a 3-yr period, followed by reverting to recommended grazing rates and measuring fluxes for a 3-yr period. During the initial year (2003) grazing heavily resulted in a net carbon balance of -92 g
m-2 compared to +33 g m-2 for a moderately grazed area for a difference of -125 g m-2. It appears that the mid-season dry conditions accentuated the carbon losses from the system on the heavily-grazed area compared to the moderately-grazed in 2003. Incomplete carbon flux data from 2004 show similar relationships to those in 2003 between moderately-grazed and heavily grazed areas.
Pan, Yude (USDA-Forest
Service, Northern Global Change Program, 11 Campus Blvd, Newtown Square PA 19073; Phone: 610 557 4205; Fax:
610 557 4095; Email: ypan@fs.fed.us)
Forest Carbon
Dynamics Under Changing Atmospheric Chemistry and Climate in the Mid-Atlantic
Region
Y. Pan*, R. Birdsey, J. Hom, K. McCullough
Changes in atmospheric chemistry and physics due to human activities are causing widespread impacts on terrestrial ecosystems. Besides the effects of climate change induced by greenhouse gases, elevated CO2, O3 and N deposition also have direct impacts on ecosystem dynamics and functioning. This study uses an ecosystem modeling approach to investigate how these multiple environmental changes interactively affect carbon dynamics in Mid-Atlantic forests that cover approximately 460,000 km2 of lands. Our results indicate that elevated CO2 increases forest productivity, but the enhanced growth was largely reduced by troposphere O3. Currently, higher N deposition interacts with higher CO2 to increase forest C sequestration. However, continued deposition of N at high levels will cause many areas to become saturated as other growing factors become limited. As forests become saturated with N, carbon accumulation in forest woody product will be reduced, and water quality will be degraded because of an abrupt increase in N export. Changes in interannual variability of climate during past decades add complexity to forest responses to changing atmospheric chemistry. More fundamentally, these multiple stresses together have likely altered basic forest biological processes and physiology. We validated the modeling results with observations from forest inventory and the MODIS satellite. The model-data comparison demonstrates that the ecosystem modeling approach is robust in this regional carbon study.
Park, E.J. (Michigan
State University, Dept. of Crop and Soil Sciences, East Lansing, MI, 48824; Phone:
517-355-0271, ext. 247; Fax: 517-355-0270; Email: parkeun2@msu.edu)
Spatial Distribution of Lignin Biopolymers and Aggregate
Stability of Forest and Tilled Soil Types
E.J. Park*, K. Dria, D. Gamblin, T.R. Filley, A.J.M. Smucker
Soils are large reservoirs that mitigate global warming by
removing greenhouse gases from the atmosphere and sequestering them as soil
organic matter (SOM). One proposed mechanism is that carbon (C) is sequestered
within soil aggregate interiors during the aggregation process. Stable soil
aggregates preserve intra-aggregate porosities that do not collapse during
wetting and drying cycles. Stable micropore networks increase the retention of
carbon, which feeds back into the formation of more stable aggregates. Repeated
wetting-drying cycles change internal pore geometries and associated
microhabitats and creating more stable macro-aggregates. Research by Smucker
and coworkers (EGU Abstracts, 2004) suggest that the exterior portions of
aggregates contain greater concentrations of C and N than their interiors,
establishing gradients of δ13C values across these aggregates.
We
investigated aggregate stability by wet sieving and by polar tensile strength
crushing resistances of aggregates from agricultural ecosystems in Hoytville
clay loam and Wooster silt loam soils. Carbon contents, lignin biopolymers,
textural distributions and intra-aggregate porosities were compared. Samples of Hoytville and Wooster
soils from forest, conventional tillage (CT) and no tillage (NT) agriculture ecosystems
were gently sieved into various size fractions. Soil macro-aggregates
(6.3-9.5mm) were peeled, by mechanical erosion chambers, into concentric layers
and separated into exterior, transitional and interior regions. Alkaline CuO oxidation was used to determine the
composition of lignin, suberin, and cutin biopolymers to determine changes in
source and degradative states of the SOM.
Soil carbon contents in aggregates
from no tillage (NT) systems were 1.6 and 2.2 fold greater than conventional
tillage (CT) systems from Hoytville and Wooster,
respectively. Greater soil C contents
increased water stability of soil aggregates. Aggregate stabilities increased
as C contents exceeded 4%. C content and water stability of aggregates showed
positive correlations with intra-aggregate porosities that decreased by 6-7% in
CT aggregates. Polar tensile strengths of air-dry aggregates increased with
increasing bulk density, C, and clay content. Preliminary results indicate that both soils
show similar relative yields of lignin and hydroxyl fatty acids with a greater
abundance of lignin than cutin and suberin acids. Greater abundances (per 100mg organic
carbon) of CuO products were observed in the native
forest than in either agricultural system and in general the lignin in the
forest soils was less oxidized. For both soils, slight trends in biopolymer
concentrations were observed between the exterior, transitional and interior
regions of the aggregates from the forest and CT or NT ecosystems. These results suggest that non-disrupted and higher
intra-aggregate porosities retained more internal carbon. Compound specific isotopic
analysis is currently being utilized to better understand the source of lignin
within the aggregates.
Park, E.J. (Michigan
State University, Dept. of Crop and Soil
Sciences, East Lansing, MI 48824, Phone: 517-355-0271, ext. 247; Fax: 517-355-0270; Email:
parkeun2@msu.edu)
Increasing the Stabilization of Soil Aggregates and
Intra-aggregate C Dynamics During Multiple D/W Cycles with Glucose
E.J. Park*, A.J.M. Smucker
Increasing the recalcitrant C pool in soils requires the expansion of sorptive surface areas that promote organo-mineral complexes within soil aggregates. Additional intra-aggregate pore networks connectivity, formed during repeated soil drying and rapid rewetting (D/W), provides additional pathways for the diffusion of DOC compounds onto new sorptive surface areas. We investigated the spatial distribution and dynamics of DOC (13C-glucose) supplied to individual aggregates and its contribution to aggregate stabilization during multiple D/W cycles. Moist macroaggregates were treated with no glucose and no D/W cycles (Control), no glucose and 5 D/W cycles (D/W), and additions of 250 mg glucose-C/g soil with each of the 5 D/W cycles (G+D/W). Aggregate stability decreased significantly during D/W cycles with no C additions. Additions of glucose-C during the rewetting stage of each D/W cycle maintained soil aggregate stability throughout the 35-day incubation and increased C flux into aggregate interiors. Respiration of C was greater from exterior regions of aggregates than from interior regions of aggregates. Consequently, G+D/W treatments increased C contents within soil macroaggregate interiors and strengthened macroaggregates. These results identify additional mechanisms that explain how plant residues, associated with no tillage agriculture, increase C sequestration by supplying constant sources of DOC that move into interior regions of stable aggregates during natural D/W cycles at the soil surface.
Parkin, Tim (USDA-ARS, National Soil Tilth Lab., 2150 Pammel Dr., Ames, IA, 50011; Phone: 515-294-6888; Email: parkin@nstl.gov)
T.B. Parkin*, T.C. Kaspar
Field respiration measurements are commonly performed using chambers placed on the soil surface at periodic intervals. Calculation of cumulative CO2 flux over time is then estimated by linear interpolation between measurement points. Because soil CO2 fluxes often exhibit pulses following rainfall events or other pertubations (i.e. tillage), measurements at infrequent intervals may fail to adequately characterize the temporal flux dynamics. If this occurs biased estimates of cumulative CO2 loss may be obtained. This paper explores the use of autocorrelation analysis to improve interpolation between measurement points, and thus, improve estimates of cumulative CO2 flux from soil respiration. An automated chamber was used to measure soil CO2 fluxes at hourly intervals from a fallow soil from April 16 through Sept. 5, 2001. All the hourly measurements were then used to compute cumulative CO2 flux from the site. This value was used as the best estimate of cumulative CO2 flux. Two interpolation techniques (linear interpolation and autocorrelation analysis) were then tested with regard to well they provided estimates of cumulative CO2 flux relative to the best estimate. In this analysis the population of hourly chamber fluxes was subsampled by selecting individual hourly flux measurments at intervals ranging from 1 d to 20 d. The two interpolation techniques were then applied and a cumulative flux for each technique was calculated. We observed that there was no difference in the two interpolation techniques when sampling interval was 4 d or less. However, as sampling interval was increased beyond 4 d the variance associated with estimates obtained by linear interpolation increased, however, the variances associated with the autocorrelation estimates were substantially less and remained relatively constant. Additional evaluations are being conducted to refine the autocorrelation technique.
Parkin, Tim (USDA-ARS,
National Soil Tilth Lab., 2150 Pammel Dr., Ames, IA, 50011; Phone: 515
294-6888; Email: parkin@nstl.gov)
T.B. Parkin*, T.C. Kaspar
Soil nitrous oxide emissions
from corn/soybean cropping systems were measured from the spring of 2003
through December 2004. Two year
corn-soybean rotations were established in plots subjected to plow tillage
(fall chisel plow, spring disk) and no-till.
A no-till corn/soybean/rye cover crop system was also evaluated. Four replicate plots of each treatment were
established with both crops of the rotation represented in each of the two
growing seasons. Nitrous oxide fluxes
were measured weekly during the periods of April through October, bi-weekly
during March and November, and monthly in December, January and February. Duplicate PVC anchors (30 cm diameter) were
installed in each plot and supported soil chambers during the gas flux
measurements. Flux measurements were
performed by placing vented chambers on the anchors and collecting gas
samples 0, 15, 40 and 45 minutes following
chamber deployment. Nitrous oxide fluxes
were computed from the change in N2O concentration with time, after
correcting for diffusional constraints.
We observed no significant tillage or cover crop effects on N2O
flux in either year. In 2003 mean N2O
fluxes were 9.2, 6.0, and 6.8 mM N2O m-2 from the soybean
plots under plow tillage, no-tillage and no-tillage + cover crop,
respectively. Nitrous oxide fluxes from
the plow till, no-till, and no-till + cover crop plots planted to corn averaged
36.1, 24.6, and 25.2 mM N2O m-2, respectively. In 2004 fluxes from both crops were higher,
but the fluxes from the corn plots were significantly higher than from the
soybean plots. Comparison of our results
with estimates calculated using the IPCC guidelines using known N inputs from
fertilizer and crop residues indicated that the IPCC estimates underestimate
actual fluxes by a factor of 5.
Paustian, Keith (Colorado State University, NREL, Ft. Collins, CO, 80523; Phone: 970-491-1547; Email: keithp@nrel.colostate.edu)
K. Paustian*, S. Williams, M. Easter, K. Killian, S. Ogle
Regional- and national-scale information on soil C changes are required for estimating greenhouse gas inventories and for assessing greenhouse gas mitigation practices and policies. We describe a methodology for estimating historical and current changes in soil C stocks in agricultural soils in the US. The method is comprised of data base servers incorporating spatial and tabular data from a variety of sources and executive programs for computation within a parallel computing environment. Input data sources, including climate, soil properties, historical land use and past and present soil and crop management practices are documented. Model sensitivities to uncertainties in historical land use practices are quantified and model predictions of historical and present soil C emissions and sinks are discussed.
Paw U, K.T. (Atmospheric
Science, University of California-Davis, One Shields Ave., Davis, CA, 95616;
Phone: 530-752-1510; Fax: 530-752-1793; Email: ktpawu@ucdavis.edu)
Eddy-covariance Measurements of Carbon Exchange from
Fields with Different Tillage Treatments in the Central Valley of
K.T. Paw U*, A.J. Ideris, A.P. King, L. Xu, J. Kochendorfer, A.A. Matista, T.C. Hsiao, D.E. Rolston.
Eddy-covariance data analyzed were collected between the fall of 2003 and the late summer of 2004, for fields with two different tillage treatments. Initially, both fields were bare (approximately from September to January), and then soil with weeds (approximately January to April), recently prepared soil (April), and finally a maize agroecosystem (April/May onwards). Our results show a clear pattern as a function of season, weed growth, and cultural timing. Diurnal patterns were evident in all months, first related to a temperature dependence of soil respiration, and then later related to the light dependence of photosynthesis. Differences were found between the two treatments, and methods were conducted to examine if the differences were real or artifacts of the two-biomicrometeorological eddy-covariance systems.
Pendell, Dustin (Kansas State University, 332C Waters Hall, Manhattan, KS, 66506-4011; Phone: 785-532-4438; Email: dpendell@agecon.ksu.edu)
An Economic Feasibility Analysis of Manure Applications and No-Tillage for Soil Carbon Sequestration in Corn Production
D.L. Pendell*, J.R. Williams, C.W. Rice, R.G. Nelson, S.B. Boyles
Background: Interest is increasing in carbon sequestration
due to potential climate changes resulting from accumulations of atmospheric
carbon dioxide and other greenhouse gases. Potential regulation of greenhouse
gas emissions in addition to consumer interest to purchase environmentally
friendly products will provide incentives for developing efficient
sequestration techniques. One opportunity for some industries to reduce their
share of greenhouse gases is to pay another industry, like agriculture, to
reduce its emissions and to sequester carbon from the atmosphere. The economic
feasibility potential of using beef manure applications and a no-tillage versus
commercial nitrogen and conventional tillage for continuous corn production to
sequester soil carbon is evaluated. Objectives: The primary objective of this
study was to determine the cost of carbon sequestration or the value of carbon
credits needed for implementing carbon-sequestering strategies in continuous
corn production. Specific study objectives included: 1) Estimate net returns
distribution for each system using nine years of annual prices and yields, 2)
Calculate C sequestration rates from historical soil test data for each system,
3) Identify the amount of carbon dioxide released to the atmosphere due to
field operations and the production of inputs in order to create a carbon
balance sheet for each cropping system, 4) Identify the economically preferred
systems, and 5) Determine the monetary value of a C credit required to entice
producers to alter management strategies to enhance carbon sequestration. Data
and Methods: Enterprise budgets were used to estimate net returns under two
different tillage systems and three different fertility treatments. Carbon
release values from direct, embodied, and feedstock energy for the fertilizers
and chemicals applied were estimated. The estimates of C emissions were paired
with soil C data to calculate annual net C sequestration. The value of a C
credit in $/metric ton/year and $/hectare that was needed to make the returns
from systems which sequestered more carbon equivalent to other systems which
had higher net returns, but lower carbon sequestration rates were derived.
Results: The analysis indicates that the highest net return was obtained from
the system using no-till and ammonium nitrate. The second highest return was
received from the system using no-till and manure. No-tillage had higher net
returns than conventional tillage for both ammonium nitrate and manure. A
comparison of net returns by nitrogen source indicated that for both
conventional tillage and no-tillage, returns were higher for systems using
ammonium nitrate than they were for systems using manure. When soil carbon data
across the systems were compared, two results were found. No-tillage had higher
soil carbon sequestration rates than conventional tillage. Systems, which used
manure as a nitrogen source, had both higher soil carbon and net carbon
sequestration rates than systems using ammonium nitrate. These conclusions were also true when net
carbon, which accounts for emissions from the production and application of
inputs was considered. The economic analysis indicates some incentive would be
required to entice producers to adopt manure fertilization strategies as a
means of sequestering carbon. The value of a carbon credit required to switch
from NH4NO3 to manure using conventional tillage at a 168
kg/ha application rate is $37/metric ton/year. A carbon credit of $374/metric
ton/year would be required to switch from NH4NO3 to
manure at a
168 kg/ha application rate using no-tillage.
Peterson, Thomas D. (Penn State University, Center for Integrated Regional Assessment, 3421 Andover Drive, Fairfax, VA, 22030; Phone: 703-691-2199; Fax: 703-691-2199; Email: tdp1@mac.com)
Development, Design and Full Life Cycle Analysis of
Forestry Climate Change Mitigation Options for the State of
T.D. Peterson*, J.D. Kartez, J.E. Smith
In
2003 Maine Governor John Baldacci signed the nation’s first state law (PL 237) requiring
a state greenhouse gas mitigation plan with greenhouse gas emission targets and
timetables. The act required formulation of consensus policy recommendations to
the governor and legislature, including terrestrial carbon sequestration.
Forestry actions were developed through a science intensive, stepwise process
of joint fact-finding and joint modeling with stakeholders, a technical working
group, and a special forest experts group (including the US Forest Service).
The USDA Forest Service FORCARB2 carbon stock inventory was used for initial
state inventory assessment and base case projections, and revised for state
policy development based on technical work group and expert review. General
revisions to FORCARB2 included technical updates and use of state specific data
to replace regional estimates (for tree growth and soil carbon equations), data
augmentation and new protocols for forest carbon accounts (for land use change,
harvested wood products imports and exports), and the use of a consumption based
inventory system (for post harvest biomass). A comprehensive menu of potential
forestry mitigation options was developed by the technical work group,
including three categories identified as priorities for analysis, including: 1)
reducing the rate of forestland cover loss through growth neutral policies; 2)
increased stocking of forested and non forested lands; and 3) commercial
density management and thinning, with harvested biomass directed to biomass
energy feedstocks and durable wood products. Full
life cycle analysis was used to evaluate net carbon impacts of pre harvest and
post harvest biomass. Results indicate significant potential for
cost-effective, net carbon savings through carefully designed forestry policy
actions, accounting for 17 percent of the overall state effort toward meeting
legislative targets. Initial evaluations of similar measures in the Northeast
Region suggest similar potential benefits and costs when scaled to available
forest acreages. Additional policy research is recommended on the dynamics of
carbon flux for developed lands, wetlands, extended forestry rotations, afforestation of non forested lands, building materials
displacement, and biomass power generation technology.
Estimated GHG
Reductions, Costs/Savings Of Maine Forestry Mitigation Options
|
State Forestry Mitigation Policy Option |
Annual GHG Reductions In 1000’s MTCE |
Annualized Dollar Costs Or Savings Per MTCE |
|
Reduced Conversion Of
Forestland To Nonforest Cover |
376 |
$-23.75 (cost savings) -
$21.85 |
|
Increased Stocking Of
Poorly Stocked Forestlands |
531 |
$3.72 |
|
Early Commercial Thinning,
Regular Light Harvests |
239 - 332 |
$2.20 – $11.88 |
Petsonk, Annie (Environmental Defense, 1875 Connecticut Ave # 600, NW, Washington, DC, 20009, Phone: 202-387-3500; Fax: 202-234-6049; Email: apetsonk@ed.org)
Compensated Reduction: An Innovative Framework to Provide Incentives for Reducing Greenhouse Gas Emissions from Tropical Deforestation
A. Petsonk*, S. Schwartzman
Greenhouse gas
emissions from tropical deforestation are significant -- as much as 20-25% of
global emissions. Bringing these under
management would further the central goal of the UN Framework Convention on
Climate Change, namely stabilizing atmospheric concentrations of the gases at a
level, and in a timeframe, that avoids “dangerous anthropogenic interference”
with the climate system. Santilli et al. have proposed the concept of “compensated
reduction,” whereby countries that elect to reduce national levels of
deforestation to below a historical baseline level, e.g. 1980-1990 level, would
receive post facto compensation,
provided the countries commit to stabilize or further reduce deforestation in
the future. Here we explore the potential of such a framework to provide
large-scale incentives to reduce tropical deforestation, as well as for broader
developing country participation in the effort to combat climate change. We also evaluate and address a range of
practical concerns.
Pierce, Danielle L. (University of California-Davis, 1010 Wickson Hall, One Shields Ave., Davis, CA, 95616; Phone: 530-754-7144; Fax: 530-752-0382; Email: dlpierce@ucdavis.edu)
Conservation Tillage of Cover
Crops as a Means of Improving Carbon
Storage in California Vineyards D.L. Pierce*, K.L. Steenwerth, D.R. Smart
There are nearly one million acres of grapes in California and only about 16% are sown to cover crops, suggesting there is potential for increasing this management practice in vineyards. Tillage of cover crops generally increases soil respiration by bringing organic residue in contact with soil microbes and exposing it to soil conditions that favor mineralization like higher moisture content and aeration. Tillage also breaks up aggregates and makes previously encapsulated C available to mineralization processes. We examined the carbon sequestration potential of conservation tillage of a vineyard cover crop in the Napa Valley, CA. A cover crop of barley was planted between vineyard rows in November of 2003, and subplots were isotopically labeled with 13CO2. We have shown in the first season of this investigation that 13CO2 labeling can be used to monitor C turnover by estimating source 13C content of soil respired CO2. We observed immediate 13C enrichments in soil respired CO2 in the conservation and conventional tillage treatments that were due to the decomposition of isotopically labeled fresh plant material. An ensuing depletion of 13C may have indicated a reduction in available 13C labeled soil organic carbon (SOC). The conservation tillage treatment showed a slower rate of change (13C loss) relative to the conventional tillage treatment, but the rate of change was strongly dependent on precipitation events following summer drought. Conventional tillage decreased soil moisture overall, but also increased maximum soil temperature and the rate of SOC mineralization. Our investigation is providing information on how minimum tillage of cover crops might help mitigate the observed increase in CO2 concentration in the atmosphere.
Ping, Chien-Lu (University of Alaska-Fairbanks, Palmer
Research Center, Palmer, AK, 99645; Phone: 907-746-9462; Fax: 907-746-2677;
Email: pfclp@uaa.alaska.edu)
C.L. Ping*, E.C. Packee, G.J. Michaelson, Y.L. Shur, J.M. Kimble
Boreal forests cover nearly one-third of the earth’s land surface and store more than 35% of the terrestrial carbon. Generally, drainage has been regarded as the controlling factor for soil organic carbon (SOC) stores in the boreal forest region with C stores increasing with more restricted drainage. However, recent findings indicate surface erosion after forest fire plays an important role in the soil carbon flux. The objective of this study was to evaluate SOC stores along a toposequence and show the relationships among fire, erosion, and SOC fluxes in boreal Alaska. Detailed soil morphological techniques were used to identify buried carbon due to solifluctuation and surface erosion-deposition during the Holocene. Organic C content was measured by a CNH analyzer after inorganic C was removed from the soil samples. Well drained upland soils generally hold 8-20 kg C m-2 but, the poorly drained bottomlands store more than 100 kg C m-2 to a 2 m depth. Nearly 70% of the C stored in the poorly drained sites are buried and below the modern soil profile. The stratified mineral and organic layers reflect landscape processes. Nearly all buried layers have abundant charcoal particles and charred wood residues that suggest they were deposited after a fire when the vegetation was destroyed and the land surface became susceptible to erosion. The redeposited C and soil layers were than encased in the rising permafrost table. Thus, in the closed basins and valleys of interior Alaska, where boreal forests are the major landcover type, fire-induced erosion becomes an important factor affecting SOC flux. This frozen C will, then, again enter into a more active part of the biogeochemical cycle once the permafrost thaws due to global climate change, fire, or changing land use and then contribute to the greenhouse gas effect.
Pizarro, Carolina (USDA-ARS, 2231 California Street,
NW, Apt. 709, Washington, D.C., 20008; Phone: 301-504-7327; Email:
CPIZARRO@anri.barc.usda.gov)
Soil Microbial Biomass, Carbon Pool, and Green House Gas Fluxes in a Long Term Tillage Experiment on the North Atlantic Coastal Plain
H. De-Polli, C. Pizarro*, T.R. Coser, G.W. McCarty, J.L. Starr
Soil microbial biomass (MB) is an important component of soil organic matter and also plays an important role on the exchange of green house gases (GHG) within agricultural ecosystems. To assess impact of plow tillage and no tillage management on long term carbon sequestration as well as the short term balance of GHG emissions from agricultural land, measurements of total soil carbon stocks (including correction for bulk density), MB related attributes and GHG emissions were performed on a tillage experiment under 10 years of continuous culture of corn (Zea mays L.). The soils were characterized within depth ranges ( 0-2.5, 2.5-5, 5-12.5 and 12.5-20 cm) and the measured microbial attributes included microbial biomass C (MBC) and N (MBN), respiration, metabolic quotient (qCO2), %MBC in total C. GHG measurements were performed throughout one year using a static chamber technique. When comparing plow and no tillage treatments, soil density was higher for no tillage at all depths with the greatest difference within the second depth range. The no tillage soil had higher total carbon stocks (0-20 cm) than plow tillage (6% by volume equivalent and 10% by mass equivalent) with the main difference occurring in the top layer of soil (0-2.5 cm). This was also the case for respiration, N, MBC, and MBN with values being much higher in the top layer for no tillage and the difference between the two treatments decreasing with depth. Values for qCO2 (specific respiration) were similar at 0-2.5 cm depth for both treatments but higher for plow tillage with increasing depth. With respect to net GHG emissions, plow tillage soil had a tendency for net CH4-C production and no tillage soil had a net consumption of atmospheric CH4-C throughout the year. This differential in CH4 dynamics between treatments was greatest in winter and early spring. In general N2O emissions were higher for the no tillage than for the plow tillage treatment, but at some sampling times the opposite was found. The highest N2O-N emission occurred during summer; although sampling period related to short drought, measured emissions were as low as the winter period. CO2-C emissions did not show a significant difference between the two treatments in most cases, and emissions were low during winter and high during summer. The calculation of global warming potential (GWP-100yr) based on these short-term emission measurements of GHG gave slightly higher carbon equivalent (Ceq) value under plow tillage than no tillage with an overall difference of 1.05 mg Ceq m-2 h-1.
Pouyat, Richard (USDA-Forest Service, Northeastern Research Station, c/o Baltimore Ecosystem Study, 5200 Westland Blvd., Baltimore, MD, 21227; Phone: 410-455-8014; Fax: 410-455-8025; Email: rpouyat@fs.fed.us)
R. Pouyat*, I.D. Yesilonis, P.M. Groffman, J. Russell-Anelli
Urban land-use change can potentially affect
biogeochemical cycles through altered disturbance regimes, landscape management
practices, built structures, and changes in environmental factors. These changes have created novel ecosystems,
which have the potential to significantly affect carbon pools and fluxes. For urban ecosystems, very little data exists
to assess whether urbanization leads to an increase or decrease in soil organic
carbon (SOC) pools. We update previously
presented data from research in Baltimore and data mined from the literature to
calculate SOC changes due to urban land-use change. For a 1000 ha hypothetical urban landscape in
the mid-Atlantic region, we estimate a loss of 5 kg C x 10-6 if the
native landscape was previously dominated by hardwood deciduous forest. In contrast, we estimate a gain of
approximately 4 kg C x
10-6 if the native landscape was predominately a desert ecosystem. These data suggest that the net change in SOC due to urban land-use change will depend on the native ecosystem replaced. For those soils with low initial SOC densities, there is potential to increase C sequestration through management. However, specific urban related management techniques and the effect of site history need to be evaluated.
Prior, Stephen A. (USDA-ARS, National Soil Dynamics
Laboratory, Global Change Research, 411 South Donahue Drive, Auburn, AL, 36832;
Phone: 334-844-4741 ext.143
Fax: 334-887-8597; Email: sprior@acesag.auburn.edu, sprior@ars.usda.gov)
Elevated Atmospheric CO2 Effects
on Residue Decomposition of Different Soybean Varieties
S.A. Prior*, H.A. Torbert, G.B. Runion, H.H. Rogers, D.R. Ort, R.L. Nelson
Elevated atmospheric CO2 can result in larger plants returning greater amounts of residues to the soil. However, the effects of elevated CO2 on carbon (C) and nitrogen (N) cycling for different soybean varieties has not been examined. Aboveground residue of eight soybean varieties (Glycine max [L.] Merr.) was collected from a field study where crops had been grown under two different atmospheric CO2 levels [370 ppm (ambient) and 550 ppm (free-air carbon dioxide enrichment) (FACE)]. Senesced residue material was used in a 60-day laboratory incubation study to evaluate potential C and N mineralization. Residue N concentration was usually increased by FACE, but residue C concentration was not altered. Varietal differences were observed with the oldest variety having the lowest residue N concentration and highest residue C:N ratio. Residue C:N ratio was lower under FACE, which could be attributed to increased N fixation. Mineralized N was usually increased by FACE, except for a non-nodulating variety, suggesting that increased N fixation impacted residue decomposition. Mineralized N was lowest in the oldest variety illustrating the influence of high residue C:N ratio. Across varieties, mineralized C was increased slightly by FACE, however, differences in varieties suggest that the impact of elevated CO2 on C mineralization could be influenced by soybean variety selection
Prueger, John (USDA-ARS, National Soil Tilth Laboratory, 2150 Pammel Drive, Ames, IA, 50011; Phone: 515-294-7694; Fax: 515-294-8125; Email: prueger@nstl.gov)
Comparison
of Tower and Aircraft Eddy Covariance Measurement of CO2 and H2O
Fluxes Over Corn and Soybean Fields in
J.H. Prueger*, J.L. Hatfield, W.P. Kustas
Individual field (corn, Zea mays L., or soybean Glycine max (L.) Merr.) measurements of CO2 and H2O fluxes provide valuable information on exchange processes but are inherently limited to the individual fields in which the measurements were made. Scaling field measurements to watershed and regional scales has important implications to operational forecast models that focus on hydrological processes and carbon uptake. To achieve this goal, a set of direct-measurement/remote sensing/modeling approaches are needed to understand how horizontal heterogeneities in vegetation cover, soil moisture and other land-surface variables influence the exchange of H2O and CO2 with the atmosphere. The Soil Moisture Atmosphere Exchange study (SMACEX) was a combined measurement and modeling program with the intent to rigorously link remotely sensed data and operational forecast models. Previous field and remotely sensed observations support the analysis of heterogeneities that range from within field or patch scale (~100 m) to the regional scales that are commensurate with prediction models of weather and climate (10-100 km). In this paper we evaluate 12 eddy covariance/energy balance towers equally distributed across typical production size fields of corn and soybeans with measurements made with the Canadian Twin Otter aircraft. Comparison of mass and energy fluxes between tower and aircraft measurements was well correlated for net radiation, latent and sensible heat fluxes and CO2 fluxes. Details of the measurement campaign, data processing and analysis will be presented.
Reddy, K. Raja (Mississippi State University, Dept. of Plant and Soil Sciences, 117 Dorman, Mississippi State, MS, 39762; Phone: 662-325-9463; Fax: 662-325-9461; Email: krreddy@ra.msstate.edu)
Effect of Different Temperatures and Carbon Dioxide Levels on Biomass Accumulation and Partitioning in Big Bluestem (Andropogon gerardii)
K.R. Reddy*, V.G. Kakani, R.L. King
Rangelands occupy 61% of United States and would play a major role in sequestering atmospheric carbon under projected climates with elevated CO2 and temperatures. The objective of this study was to evaluate the effect CO2 and temperature interaction on biomass accumulation and partitioning in Andropogon gerardii, a dominant C4 species in tallgrass prairies. Ten sunlit Soil-Plant-Atmosphere-Research chambers were used to study the effects of two CO2 levels (360 and 720 ppm) and five different temperatures (20/12, 25/17, 30/22, 35/27 and 40/32 ºC; day/night). Grass seeds were sown in 11 rows at 0.2 m spacing and after emergence were thinned down to ten plants per row. A predetermined combination of CO2 and temperature was maintained from sowing to maturity under optimum water and nutrient conditions. At maturity, individual plants were harvested and divided into leaves, stems and panicles. The roots were dug out from the soil bin into 4 layers at 25 cm interval in each of the SPAR units and thoroughly washed to remove sand particles. The samples were then oven dried at 70º C for 72 h and dry weights were recorded. Biomass decreased either above or below the optimum temperature of 30/22º C. The effect of elevated CO2 on biomass accumulation (12-30% increase) was observed at or less than optimum temperature (30/22º C)and vanished at higher temperatures. With increase in temperature, irrespective of the CO2 level, biomass partitioned to leaves increased (35%) where as that to stems decreased (33%). Panicle weight was 6-7% of biomass at 25/17º C and fell to 1.6% at 40/32º C. The biomass partitioned to roots, across the temperatures, was constant for plants grown at 360 ppm CO2 but decreased by 7% for those grown at 720 ppm. The study suggests that at above optimum temperatures (above 30/22º C) the selected C4 tallgrass prairie species, Big Bluestem, fails to capture higher amounts of carbon under elevated CO2 conditions but partitions more to leaves for later incorporation into soil. The decrease in panicle production at higher temperature would also reduce the selected C4 species population and dominance in tallgrass prairies.
Revanuru, Sucharitha (ICRISAT, Patancheru, AP,
India, Bldg 212/First Floor, Systems Modeling, ICRISAT, Near Hyderabad, AP,
502324, India; Phone: 91 4030713438; Fax: 914030713075; Email:
s.revanuru@cgiar.org)
Simulation
of the Effects of Manure Quality, Soil Type, and Climate on N and P Supply to
Sorghum and Pigeon pea in Semi-Arid Tropical
S. Dimes, S. Revanuru*
Experimentation in India examined the response of sorghum and pigeon pea to inputs of low and high quality manures on N and P responsive alfisol and vertisol soils. A special feature of the work is that inorganic fertilizer treatments were included to help quantify the cereal and legume responses to the N and P content of the manure. This paper provides a brief overview of the Indian experiments and results, and reports on the performance of APSIM to simulate aspects of the observed legume and cereal crop responses to N and P inputs, and the residual legume benefits to a following cereal. For this preliminary evaluation, the model performed poorly in simulating the observed P response at low N levels. However, further modifications to input parameters for the P model, especially in relation to P supply and uptake for deeper soil layers may improve the fit between observed and predicted results. In contrast, APSIM performed well in predicting the growth of pigeon pea and the residual N benefits to a following cereal crop, including the response to additional inputs of N fertilizer.
Riedacker, Arthur C. (INRA, 63 Bd, de Brandebourg, 94205, Ivry Cedex, France;
Phone: 33 672 39 76 46; Fax: 33 1 46
70 41 13; Email: a.riedacker@wanadoo.fr)
Short-term and Long-term Approaches
to Reduce Greenhouse Gas Emissions from “Land Use, Land Use Change, Bioproducts
& Transport” Systems
A.C. Riedacker*,
J.A. Racapé
Under the Kyoto Protocol
annual greenhouse gas emissions (GHG) of France are to return to the 1990 level
during the first commitment period.
However to stabilize GHG concentrations in the atmosphere global
anthropogenic GHG emissions at the global level are to be divided by 2 at the
turn of the middle of this century, or a little later. An equitable North South burden sharing may
therefore require to stabilize emissions in developing countries and to divide
them by 4 in industrialized countries.
UNFCCC GHG inventories allocating emissions by sectors were designed for
international negotiations. This approach is useful for industrial sectors but
inappropriate to find out the appropriate policies and measures to be
considered when dealing with sources and sinks for food and non food bioproducts related with land use, land use change, their
production, conversion and transport. For the latter system, emissions and
avoided emissions need a comprehensive spatial, (cropland grassland forests and
other land), temporal (from 10 to 100years) and integrated (of agriculture,
forestry, energy, raw material etc.) approach; the “LU, LUC, B & T” approach
(for the “Land Use, Land Use Change, Bioproducts and Transport” approach). An even more comprehensive approach should
also take into account other environmental (water and atmospheric pollutions,
biodiversity etc.), cultural and socioeconomic concerns for sustainable
development.
First we consider emissions reduction options under the “UNFCCC”
approach and its limitations, in particular for France. In a second step we
consider a narrow “LU, LUC, B & T” approach, in which only within
countries emissions are taken into account. At a further stage international
exchanges and transportations are of course also to be considered. The primary
objective is to allow farmers to assess “on farm” options (modelling) under
these two approaches and to allow also policy makers to propose adequate
policies and measures.
A more long term objective,
taking into account the mid century objective of stabilisation of GHG
concentrations in the atmosphere and sustainable development, will have to
consider more drastic reductions. We suggest that this needs probably at least
a four-pronged approach taking into account, inter alia,
possible technological changes, technical limitations as well as cultural
habits;
- “top down
approaches” in agriculture and forestry and use derived products, e.g.
reductions of net emissions of various sub-systems (in crop production,
livestock production, forestry, bioenergy and
biomaterial production etc.);
- “bottom up
approaches”, taking into account socio-economical and technical limitations
of changes in land use, in land use changes, conversion and use of bioproducts
from various agro and forestry systems, in particular in constrained eco-socio-systems such as
mountainous regions, semi arid regions etc.;
- “end users
approaches”, starting from the basic needs of bioproducts
by end users such as food (calories, proteins, lipids), energy (bioenergy and others) and materials (construction wood,
green steel, latex etc.);
- and finally a
“global economical” modelling.
Rolston, Dennis (University of California-Davis, Land, Air and Water Resources, Davis, CA, 95616; Phone: 530-752-211; Fax: 3530-752-1552; Email: derolston@ucdavis.edu)
D.E. Rolston*, C. Van Kessel, J.W. Hopmans, J. Six, K.T. Paw U, R. Plant, A.P. King
Conservation tillage practices may lead to an increase in soil C, partially offsetting greenhouse gas (GHG) emissions. The overall objectives for this presentation are: (1) to identify and quantify C input pathways and their spatial and temporal variations at the field scale; and (2) to determine the effect of minimum versus standard tillage on the spatial distribution of the controlling factors and resulting short-term rates of GHG fluxes. Our expected results are essential for testing models and for scaling up of C sequestration potential from the field and landscape to the regional level. The research site (30.8 ha) in Yolo County, CA is furrow-irrigated and was in minimum-till wheat prior to the initiation of the experiment. Extensive baseline data on total soil C, N, bulk density, particle size, residue yield, and root biomass were collected before the site was split into two fields to represent the grower’s standard tillage (ST) and minimum tillage (MT) practices. The ST field was tilled in October 2003 and both fields were planted with corn in April 2004. Each field is instrumented with: 1) eddy-covariance instruments to measure field-scale carbon dioxide fluxes, 2) automated chambers for assessing the temporal pattern of carbon dioxide and nitrous oxide fluxes, and 3) multiple portable chambers to evaluate the spatial characteristics of carbon dioxide, nitric oxide, and nitrous oxide fluxes. The soil profile is also instrumented to measure various physical soil variables, such as soil temperature, water content, and carbon dioxide and nitrous oxide soil air concentrations. For the first year of this long-term study, using the eddy covariance approach, the ST treatment exhibited approximately triple the photosynthetic uptake of the MT treatment for May, but the MT caught up with the ST by July. The differences in corn growth were evident in the visual appearance of the fields and was also reflected in the grain yield with the MT being smaller than the ST. Overall, similar magnitudes and patterns of carbon dioxide fluxes were measured with the chambers and the eddy-covariance method, although the chambers appear to be giving slightly smaller fluxes (measured during the middle of the day) than the nighttime carbon dioxide exchange as measured by the eddy-covariance approach. This difference is most likely due to nighttime plant respiration. Flux data from the automated chambers corresponded to the diurnal patterns determined with the eddy-covariance approach. Very little or no emission of nitric oxide and nitrous oxide occurred during the fallow period. Soon after planting of the corn and fertilization, the mean monthly nitrous oxide fluxes increased gradually from March through June to a maximum of about 0.2 mg N m-2 s-1 and then decreased to about half the peak values in July. Only minor differences were apparent in nitrous oxide fluxes between the two tillage treatments. As expected, large emissions occurred directly over the fertilizer band. It is expected that several more years of measurements will be required in order to determine any differences in GHG gas emissions and C sequestration between the two tillage treatments, especially in light of the yield depression for the MT treatment.
Rondon, Marco (Centro Internacional de
Agricultura Tropical, A.A. 6713, CIAT, Cali, Colombia; Phone: 57-2-4450000; Fax:
57-2-4450073; Email: m.rondon@cgiar.org)
M.A. Rondon*, J.A. Ramirez, J. Lehmann
Charcoal is a ubiquitous material that has been used in agriculture by several cultures throughout history. Increasing evidence indicates that in very low fertility soils, additions of charcoal could increase plant yield and improve several soil quality indicators. Charcoal is a very stable material in soils, with residence times in the order of thousands of years contrasting with mean residence times of decades to centuries for most other soil organic matter pools. Charcoal additions could be used as a mechanism for long-term storage of C in soils and can play a key role for mitigation of climate change and to improve naturally unfertile or degraded soils. There is no information so far, however, related to the effects of charcoal additions to soils on net fluxes of greenhouse gases and on the overall global warming potential of soils amended with charcoal. Here we present results from a glasshouse pot experiment, where very acid, low-fertility oxisols (typic haplustol) from Colombian savannas were amended with 0, 7.5, 15, and 30 g kg-1 of charcoal. Soybeans and a tropical grass (B. humidicola) were planted and allowed to grow for 50 days. Plant yield and total biomass were measured at harvest time and the soil tested for various nutrients. Monitoring of fluxes of nitrous oxide and methane was done using the closed vented chamber approach. Gas samples were collected at two-weeks intervals after planting. Analysis of methane and nitrous oxide was conducted by gas chromatography using FID and ECD detectors. Total net fluxes of methane and nitrous oxide from pots cropped to soybean and B. humidicola were significantly reduced by the addition of charcoal. Methane emissions were virtually suppressed in the grass pots already at charcoal additions of 20g kg-1 soil. Nitrous oxide emissions were reduced by up to 50% on soybean and by 80% in grass pots. At the same time, biomass production of soybean was positively affected by increasing charcoal additions, with a 60% increase after charcoal additions of 20 g charcoal kg-1 soil. In contrast, biomass of B. humidicola did not change with charcoal additions. Charcoal effectively increased soil pH, CEC and availability of various soil nutrients. This study showed that additions of moderate doses of charcoal to very acid and nutrient-limited soils not only enhance plant yields especially of legume species, but also result in drastic reductions in net emissions of methane and nitrous oxide from soils. Given that most of the added charcoal-C remains unmineralized in the soil due to its chemical recalcitrance, a clear positive effect of charcoal additions to soils was observed on net reductions of total emissions of greenhouse gases to the atmosphere. To our knowledge, this is the first study in exploring charcoal effect on GHG emissions. Further research is needed to establish the response of different charcoals in contrasting soil types and with other plants species.
Ruhweza,
Alice (NEMA-UGANDA, National Environment Management Authority (NEMA), Kampala,
Uganda; Phone: +25631271634; Fax: +25631271635; Email: aruhweza@nemaug.org)
Mainstreaming
Payments/Incentives for Ecosystem Services in Regional and National
Planning/Policy Dimensions
A. Ruhweza*
Over the
past several centuries, food and fiber production—both produced by agriculture
(domesticated crops, livestock, trees and fish) and harvested from natural
systems (forests, grasslands, and fisheries)--has come to be the dominant
influence on rural habitats outside the arctic, boreal, high mountain and
desert ecoregions. Unfortunately, most
food production systems have had highly negative impacts on wild plant and
animal biodiversity (both directly and through loss of habitat), and on
ecosystem services critical to human well-being, such as regular water supply
and quality, control of pests and diseases, pollination of useful plants, and
sequestration and storage of carbon. These losses have direct and indirect
economic impacts.
In Uganda and other parts of
Africa, diverse land use systems have been developed by farmers and scientists
that increase agricultural productivity, while also enhancing biodiversity of
ecosystem services, and benefiting farmers economically, for example:
No Tillage/Zero Tillage - which leads to prevention of soil
erosion and maintenance of soil health;
Integrated Agriculture - whereby land is used to rear animals
and crops. Cow dung is used to
enrich the soil;
Agro Forestry - whereby a
number of farmers are planting trees with their crops, which also leads to soil
and water conservation;
Management of soil erosion
in the bare hills – through tree planting, etc;
Small scale irrigation to
mitigate effects of drought - high value crops horticulture;
Rain water harvesting to
increase nutrients recycling and improved soil health;
Upland Rice has been
promoted extensively to mitigate the destruction of wetlands.; and
Trees for Global Benefits -
The Environmental conservation trust of Uganda has been working with a number
of partners and District local government have implemented a pilot carbon
trading scheme that works with small scale holder farmers. The project promotes
tree planting activities under different tree growing configurations –
woodlots, agro forestry, boundary planting while at the same time promoting
income generating activities like beekeeping and goat rearing. Emphasis has been placed more on indigenous
tree species as a way of restoring on farm tree diversity.
However, most of the
negative environmental “externalities” resulting from conventional agriculture
are not internalized as business costs, and there is little financial reward to
the farmer for producing positive environmental externalities, especially when
ecosystem-damaging systems are heavily subsidized by governments. While
improved science and technology will play a critical role in generating lower-cost
systems that also benefit the environment, radical changes are also needed in
financial incentives. Much innovative work is already underway to create such
incentives, e.g. markets for “green” products, using a variety of certification
systems (certified organic; certified biodiversity-friendly, Forest Stewardship
Certification, etc.); agro ecotourism that attracts tourists to farms or
farming regions that are also rich in wild biodiversity; tax systems that
reward farmers and ranchers for maintaining biodiversity or good watershed
features; payments to farmers to maintain protected areas for important species
or ecosystem functions; payments to farmers for managing their farms in ways
that conserve important species or ecosystem functions; e.g. carbon sequestration;
and payments to farmers or forest owners for bioprospecting
rights.
This paper will look at some
of the initiatives underway in Uganda and explore the potential to enhance them
into full-scale markets for ecosystem services.
Runion, G. Brett (USDA-ARS, NSDL, 411 S. Donahue Drive, Auburn, AL, 36832; Phone: 334-844-4517; Fax: 334-887-8597; Email: gbrunion@ars.usda.gov)
Effects of Elevated Atmospheric CO2 on Biomass and Carbon Accumulation in a Model Regenerating Longleaf Pine Ecosystem
G.B. Runion*, M.A. Davis, S.G. Pritchard, S.A. Prior, R.J. Mitchell, H.A. Torbert, H.H. Rogers, R.R. Dute
Community response to elevated CO2 was examined in a model regenerating longleaf pine ecosystem exposed to two CO2 regimes (ambient, 365 ìmol mol-1 and elevated, 720 ìmol mol-2) for three years using open-topped chambers. Total aboveground and belowground biomass was 70% and 49% greater, respectively, in CO2-enriched chambers; carbon (C) content followed a similar CO2 response pattern which resulted in a significant increase of 12.2 Mg C ha-1 sequestered in standing biomass, with an additional increase of 1.6 Mg C ha-1 in litter. Responses of individual species, however, varied. Longleaf pine (Pinus palustris) was primarily responsible for the positive response to CO2 enrichment (88%). Wiregrass (Aristida stricta), rattlebox (Crotalaria rotundifolia), and butterfly weed (Asclepias tuberosa) all exhibited negative aboveground (-26%, -53%, and -65%, respectively) and belowground (-36%, -43%, and -52%, respectively) biomass responses to elevated CO2; C content responses again followed patterns similar to biomass. While sand post oak (Quercus margaretta) had positive responses to CO2 enrichment (39% and 12% for above- and belowground, respectively), these did not differ significantly between treatments due to high variability. Elevated CO2 resulted in alterations in community structure; 88% of total biomass in CO2-enriched plots was allocated to longleaf pine with only 8% allocated to wiregrass, rattlebox, and butterfly weed. In comparison, ambient CO2 plots allocated only 76% of total biomass to longleaf pine but had 19% allocated to wiregrass, rattlebox, and butterfly weed. Therefore, while longleaf pine may perform well in a high CO2 world, other members of this community may not be able to compete as well as atmospheric CO2 concentration continues to rise. Regardless of individual species response, the entire system gained 11.4 Mg C ha-1 under elevated CO2 suggesting that this ecosystem should be a sink for atmospheric CO2.
Sainju, Upendra (USDA-ARS, 1500 North Central Avenue, Sidney, MT, 59270; Phone: 406-433-9408; Fax: 406-433-5038; Email: usainju@sidney.ars.usda.gov)
Carbon Sequestration in Dryland Soil and Plant Residue as Influenced by Tillage and Crop Rotation
U.M. Sainju*, A. Lenssen, T.C. Ton-That, J. Waddell
Management practices may influence crop biomass yield and C sequestration in plant residue and soil in drylands of northern Great Plains. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)], five crop rotations [continuous spring wheat (CW), spring wheat-fallow (W-F), spring wheat-lentil (W-L), spring wheat-spring wheat-fallow (W-W-F), and spring wheat-pea-fallow (W-P-F)], and grasses under Conservation Reserve Program (CRP) on plant biomass (stems + leaves) returned to the soil, residue cover, amount, and C content, and soil organic C (SOC) and particulate organic C (POC) contents at 0- to 5- and 5- to 20-cm depths. A split-plot field experiment was conducted in a mixture of Elloam clay loam (fine-loamy, mixed, Aridic Argiborolls) and Kevin clay loam (fine, montmorillonitic, Aridic Argiborolls) from 1998 to 2003 in Havre, MT. Plant biomass yield varied by crop rotation and year and total biomass returned to the soil from 1998 to 2003 was greater in CW (15.3 Mg ha-1) than in other rotations. Residue cover, amount, and C content in 2003 were 33 to 86% greater in NT than in CT and greater in CRP than in crop rotations. Residue amount (2.47 Mg ha-1) and C content (963 kg ha-1) was greater in NT with CW than in other treatments, except in CT with CRP and W-F and in NT with CRP and W-W-F. The SOC at 0- to 5-cm was 23% greater in NT (6.4 Mg ha-1) than in CT. The POC was not influenced by tillage and crop rotation, but POC/SOC ratio at 0- to 20-cm was greater in NT with W-W-F than in CT with CW, W-F, and W-L. From 1998 to 2003, SOC at 0- to 20-cm was decreased by 4% in CT but was increased by 3% in NT. Carbon can be sequestered in dryland soils and crop residue using reduced tillage and increased cropping intensity, such as NT with CW, compared with traditional practice, such as CT with W-F system, thereby helping to improve soil quality and productivity and reduce soil erosion.
Sands, Ronald D (Joint Global Change Research Institute, University of Maryland, 8400 Baltimore Avenue, Suite 201, College Park, MD 20740; Phone: 301-314-6765; Fax: 301-314-6719; Email: Ronald.Sands@pnl.gov)
Competitiveness
of Agricultural Greenhouse Gas Offsets: Are They a Bridge to the Future?
R.D. Sands*, B.A. McCarl
Activities to exploit agricultural carbon sequestration, agricultural emissions reductions, and biofuel related offsets utilize largely currently known and readily implementable technologies. Many other greenhouse gas mitigation options require future technological development before implementation. However, biological soil carbon sequestration, while ready to go now, generally has a finite life, allowing use until other strategies are developed. This paper reports on an investigation of the competitiveness of biological carbon sequestration from dynamic and multiple strategy viewpoints. Key factors affecting the competitiveness of soil carbon as an alternative is considered including competition with agriculturally and forestry based biofuels, afforestation, energy sector related CO2 capture and storage, and fuel switching. The analysis is done using a mixture of a dynamic forest and agricultural sector model (FASOM) and a computable general equilibrium model (SGM) of the U.S. economy. Both models simulate U.S. greenhouse gas emission reduction efforts at various carbon prices over time. The results show that, at lower carbon prices and in the near term, soil carbon and other agricultural/forestry options are important bridges to the future, initially providing a substantial portion of the attainable greenhouse gas emission offsets, but with a limited role in later years. At higher carbon prices, afforestation and biofuels are more dominant among terrestrial options to offset greenhouse gas emissions. But in the longer run, allowing for capital stock turnover, options to reduce greenhouse gas emissions from the energy system provide an increasing share of potential reductions in total U.S. greenhouse gas emissions. In addition, data are presented on the environmental benefits of pursuing agricultural strategies.
Schlamadinger, Bernhard
(Joanneum Research, Institute of Energy
Research, Elisabethstrasse 5, A-8010 Graz, Austria; Phone: +43 316 876 1340; Fax: +43 316 876 1320; Fax
PC: +43 316 8769 1340; E-mail:
bernhard.schlamadinger@joanneum.at)
CarboInvent - Multi-source Inventory Methods for Quantifying Carbon Stocks and Stock Changes in European Forests
B. Schlamadinger*
CarboInvent[1] is a project funded by
the European Commission with an aim to facilitate preparation of GHG
inventories of land subject to forest management, afforestation, reforestation or
deforestation for UNFCCC and Kyoto Protocol reporting. The main objectives of
the project are to:
·
Identify / develop / test multi-source (remote sensing, soils, forest
inventory) methods for an improved estimate of carbon stock changes at national
/ EU levels;
·
Establish a set of biomass expansion factors and biomass equations for
major EU tree species and forest types, and assess their error ranges;
·
Develop methods for estimating soil carbon budgets;
·
Develop methods for assessing carbon stock changes occurring after
disturbances (mainly windthrow), and
·
Apply these methods in test sites and demonstrate how these methods can
be upscaled to the national level.
The ingredients mentioned
above can be brought together in two different ways:
The top-down approach, applies the NFI data as
aggregated at the regional or national level and combines them with nation wide
soil data and biomass expansion factors and supplementary information enabling
improved stratification, in order to calculate carbon stock changes at regional
and national levels. The modelling framework EFISCEN (European Forest
Information Scenario Model) and the European Forest Resource Data
Base are used in this effort.
The bottom-up approach
combines the raw NFI data at the plot level
with local data on soils and biomass equations in order to estimate changes in
carbon stocks at local levels. Next, carbon estimates at the local scale are
combined with remote sensing data to interpolate between forest inventory plots
and thus arrive at estimates integrated at the regional or national level.
Both approaches are applied, and compared to each other, at test sites representing the major climatic regions in Europe, with the aim of assessing their pros and cons for monitoring and reporting needs under the UNFCCC and the Kyoto Protocol.
Schlanser, Jill (University of California-Davis, Dept. of Land, Air, and Water Resources, One Shield Ave., Davis, CA, 95616; Phone: 530-754-6536; Email: jcschlanser@ucdavis.edu)
Tracing Dairy-Derived DOC
J.C.S. Schlanser*, P.J.H. Hernes, T.J.H. Harter
DOC transport is a critical component of carbon sequestration models, both as a source term (transport of surface-derived DOC to depth within the soil column) and a loss term (transport via groundwater to rivers where it will eventually be respired). Large dairy operations in California’s central valley generate a great deal of liquid manure which is frequently reapplied to forage crops. Because of enhanced carbon loading at the surface, these systems can be used to study different aspects of DOC transport as it relates to carbon sequestration. This study focuses on the quantity and composition of the dissolved organic matter (DOC) that is transported to groundwater from these operations, and how it is compositionally related to the liquid material applied at the soil surface. The background concentration of DOC in the region of the dairy farm is 4-6 ppm, while concentrations in groundwater within the dairy range from just above background levels to as high as 75 ppm. Within the wastewater settling ponds, DOC concentrations exceed 400 ppm. The transport of organic carbon compounds throughout the phases of a typical dairy operation is examined with a focus on a relatively conservative organic compound, lignin. Lignin is commonly used to determine the origin of organic matter and as a diagenetic indicator. Lignin phenol concentrations in the study site range between nearly 430 ppb in settling ponds to just over 10 ppb in groundwater-draining canals. These concentrations range above and below the phenolic content of riverine systems, which contain an average of 26 ppb lignin-derived phenols. Batch studies are being prepared to gain a better understanding of the potential fractionation of lignin-derived phenolic compounds between the solid and solution phases during transport of DOC through the soil column to groundwater. The results of this study will provide insight to the amount and state of carbon transported as DOC to groundwater from liquid manure fertilization, as well as refining the use of lignin phenols in organic matter characterization by describing any fractionation that may occur through leaching or interactions in the subsurface.
Scott,
Neal (Woods Hole Research Center, PO Box 296, Woods Hole, MA, 02540;
Phone: 508 548 9375 ext 145; Fax: 508 540 9900; Email: nscott@whrc.org)
Factors Controlling Carbon Sequestration at Howland Forest, Maine: Long-term Trends, Interannual Variability, and Forest Management Impacts
N.A. Scott*, D.Y. Hollinger, E.A. Davidson, D.B.
Dail, H. Hughes, J.B. Lee, C.A. Rodrigues
Several factors interact to
control rates of carbon (C) sequestration in forests, and these factors operate
over temporal scales of minutes to decades.
Measurements of C sequestration are further complicated by the fact that
storage occurs in various pools (e.g. wood, soil, dead wood). The eddy covariance technique integrates the
various fluxes of C over time scales ranging from minutes to decades, providing
critical information for development and testing of models that predict future
climate and management effects on C sequestration.
We are examining the factors
controlling C sequestration at Howland Forest in central Maine. Howland Forest is a commercial forest managed
by International Paper, located about 35 miles north of Bangor, Maine. The forest is dominated by red spruce (Picea rubens) and
eastern hemlock (Tsuga canadensis),
with small contributions from red maple (Acer rubrum),
white pine (Pinus strobus),
and northern white cedar (Thuja occidentalis).
Net annual C sequestration in an undisturbed stand (~140 years old)
averaged 1.7 Mg C ha-1 y-1 over the last decade. The majority of the C is stored in growing
trees. Interannual variations in C sequestration are driven by climatic variations;
warmer than average spring and fall conditions lead to enhanced C uptake and
warmer than average summer temperatures lead to reduced C uptake. Spatial
variability, demonstrated using two independent towers, is lower than temporal
variability. This tower serves as a
control for ongoing experimental manipulations of the C cycle at Howland Forest
(e.g. shelterwood harvest).
Forest management practices
also have a large impact on C sequestration rates. We evaluated the C
consequences of a commercial shelterwood harvest
(2001-2) at Howland Forest. This management system (three harvests over ~60 y)
has become increasingly popular over the past decade. Shelterwood harvest
removed about 15 Mg C ha-1 (~30% of live biomass), and created 5.3 and 5.2
Mg C ha-1 of detritus
(aboveground and belowground, respectively).
Respiration (decay) from aboveground slash correlated positively with
temperature and moisture. Net C storage
measured by eddy covariance in August 2001 (pre-harvest) was similar to that of
the control tower, then reduced by about 25% the first year after harvest. In 2004 (three years post-harvest), net C
storage in August had almost returned to pre-harvest levels, suggesting that C
uptake by the vegetation during the growing season recovers in about three
years after a shelterwood harvest.
Secchi, Silvia (Iowa State University, Dept. of Economics - CARD, 260 Heady Hall, Ames, IA, 50011; Phone: 515-294-6173; Email: ssecchi@iastate.edu)
Measuring Carbon Co-Benefits of Agricultural Conservation Policies: In-stream vs. Edge-of-Field Assessments of Water Quality
P.W. Gassman, H.F. Hennessy, M. Jha, S.L. Kling, L. Kurkalova, S. Secchi*
Researchers studying carbon sequestration in agricultural soils have raised the important point that activities that generate carbon sinks also have other, generally beneficial, environmental effects. These effects have been termed “co-benefits” and include water quality, bio-diversity, habitat preservation, and a range of other environmental goods. Water quality co-benefits are particularly important because of the impairment of many waterways, and the on-going process of developing total Maximum Daily Loads to improve them. Water quality impacts of conservation policy can be difficult to assess, because identical conservation practices put in place on two different tracts of land can have widely divergent water quality effects. Proximity to surface water, differing hydro-geologic settings, variation in rainfall, and other factors contribute to these differences. In general, policy assessments have largely been based on edge-of-field models, stopping short of linking conservation practices to ambient water quality and have often included only a single conservation practice or fairly simple biophysical models that do not fully incorporate the complex interactions in a watershed between conservation practices on different parcels within the same watershed. In this project, we estimate the water quality benefits of a conservation policy that would allow producers to choose between two important, but fundamentally distinct types of conservation practices to sequester carbon: (1) retirement of their land from agricultural production (akin to the CRP) or (2), adoption of low tillage practices that keep their land in active production. Both practices have the potential to improve water quality by reducing sediment loading, but at rates and costs that vary considerably across space. Further, the in-stream water quality effects may differ even more dramatically. We integrate economic models that predict the willingness of producers to adopt one of these two conservation practices with two biophysical models: , the Environmental Policy Integrated Climate (EPIC) model which predicts erosion losses and other edge-of-field environmental impacts, and the Soil and Water Assessment Tool (SWAT) model which predicts changes in ambient surface water quality. We do this for the Upper Mississippi River Basin, a large, spatially heterogeneous watershed, using the National Resource Inventory database, containing some 113,000 points in the area, to capture the heterogeneity of the costs, land, soil, and weather characteristics across the region. The carbon benefits are estimated at the NRI point level using the EPIC model. This study illustrates the importance of properly accounting for co-benefits by simultaneously estimating water quality and carbon sequestration. The assessment of the co-benefits is critical for both federal and state policy makers interested in conservation policy since it allows for more accurate cost-benefit assessment of programs. In cases in which several programs co-exist that target different environmental impacts, such analysis allows for the proper accounting of program interactions and overlaps.
Shaver, Guy (University of California-Davis, PO Box
73023, Davis, CA, 95617; Phone: 530-752- 6216; Email: gshaver@ucdavis.edu)
Exploring Field Scale Variability of Soil Physical Properties, Total Carbon, and Carbon Dioxide Flux in a California Agricultural System
G.G. Shaver*, D.E. Rolston, J.W. Hopmans, C. Van Kessel, J.W. Six, A. King, J. Lee, J. Evatt
The ability of soil to sequester carbon is dependant upon the interactions of physical, chemical, and biological states within the soil system. Scales of dependency between soil variables can range from the microscopic interactions at organo-mineral complexes to local and global patterns of heat distribution. Traditional agricultural-plot experiments generally assume weak stationarity between sample variables thus allowing for ‘independence’ between sampling locations. However, most field-scale studies reveal non-stationary mean structures and dependencies between sampling locations and soil parameters. Thus, accounting for spatial and temporal variability in agricultural systems is necessary to accurately scale-up C sequestration estimates from traditional small-scale plot experiments to local and regional ecosystem analyses. We have sampled and performed an exploratory data analysis on the clay content (% clay), bulk density (BD), total carbon (TC), CO2 flux, soil water content (swc), and soil temperature (Ts) of a 30 hectare California agricultural field, under two years of minimum-tilled wheat production followed by the division of the field into ‘conventional’ and ‘minimum’ tillage treatments and a growing season of maize. TC, % clay, and BD show non-stationary mean structures and spatial autocorrelations. Spatial-temporal relationships were found between %clay & swc (P less than 0.001), swc & TC (P less than 0.01), and Ts & CO2 flux (P less than 0.001) throughout the growing season. CO2 flux tended to have higher central medians within the conventionally tilled treatment; however, no significant difference between treatments was noted. Analyses of the ‘median-polished’ residuals from the above data sets nicely show qualitative trends between field variables at the landscape scale.
Sheffner, Edwin (NASA, Mail Stop 5L79, NASA Headquarters, 300 E Street SW, Washington, D.C., 20546; Phone: 202-358-0239; Email: edwin.j.sheffner@nasa.gov)
Collaboration Between NASA and USDA for Carbon
Management.
E. Sheffner*, R.A. Birdsey, C.S. Potter
In May 2003, the National Aeronautics and Space Administration and the US Department of Agriculture signed a Memorandum of Understanding to facilitate the transfer of NASA Earth science capabilities (observations, measurements, model output and systems engineering) to USDA agencies to assist those agencies meet their operational mandates. One of five focus areas identified in the MOU is carbon management. The MOU is being implemented through an interagency working group. Collaborative projects addressing carbon management have emerged from the working group and from solicitations sponsored by NASA and USDA. Carbon management is the re-distribution of carbon in terrestrial and aquatic environments through the implementation of policies that affect carbon emissions and sequestration. NASA contributes to carbon management through the Applied Sciences Program of the Earth-Sun System Division. The Program extends the use of NASA research results in the carbon cycle to enhance the decision support tools of NASA's operational partners with monitoring and policy mandates regarding carbon emissions and sequestration. Among the tools that have emerged from NASA's research program with potential impact on carbon management is CQUEST. CQUEST stands for “Carbon Query and Evaluation Support Tools.” CQUEST is an internet accessible set of tools for estimating and monitoring terrestrial carbon sequestration. It is now being evaluated in projects co-funded by NASA and USDA in agriculture and forestry. The forestry project will evaluate the CQUEST, and the CASA (Carnegie-Ames-Stanford Approach) ecosystem model on which it's based, at a network of experimental forests to track forest disturbance and re-growth. CQUEST can provide complementary information to ground-based forest models to enhance decision support for forest managers to estimate and report carbon stocks.
Singurindy, Olga (Cornell University, Dept. of Biol. & Env. Engineering, 104 Riley-Robb, Ithaca, NY, 14853; Phone: 607-255-2463; Fax: 607-255-4080; Email: os43@cornell.edu)
Experimental Observation of Nitrous Oxide and Ammonia Emission from Urine-affected Soils
O. Singurindy*, S.K. Giri, M. Molodovskaya, T.S. Steenhuis
Fertilizers in agriculture have been implicated as an important source of atmospheric nitrous oxide and ammonia emissions. In dairy areas the main source of fertilizer N is due to the spreading of animal waste on the agricultural land. Fifty to eighty percent of the excreted N from the animals occurs in urine with the varying proportion depending on the diet. The objectives of this study are to investigate the processes that lead to formation of these greenhouse gases and to quantify ammonia and nitrous oxide losses from urine-affected soils. For this study, a series of laboratory experiments were carried out in aerobic conditions in which urine was mixed with either sand and silt loam. Ammonia and nitrous oxide were measured at the time intervals from 20 minutes up to 6 hours. As expected, most ammonia volatilized during the first hours of the experiment and was well correlated with water loss by evaporation. In addition, soil structure and moisture content affected nitrous oxide emission rates.
Skinner, Howard (USDA-ARS, Pasture Systems & Watershed Management, University Park, PA, 16802; Phone: 814-863-8758; Fax: 814-863-0935; Email: howard.skinner@ars.usda.gov)
H. Skinner*
Land use in the Northeastern U.S. is diverse, with more than half the land area in forest, one-fourth used for agriculture, and about 14% in urban and other land uses. Grasslands occupy 3.5 million ha in this region and are becoming more important as components of low cost, sustainable, and environmentally sound forage-livestock production systems. Most available data on grassland carbon sequestration are from Great Plains and Western rangelands. Because of greater rainfall and a longer growing season, grasslands in the Northeastern U.S. have a greater capacity for plant biomass production than do rangelands. However, these same conditions also favor increased plant and soil respiration. The net effect of the balance between greater productivity and respiratory loss on carbon storage is not known. Net carbon storage also depends on biomass removal and utilization. In animal production systems, biomass is removed from pastures either by grazing or mechanical harvest. Because a direct relationship exists between carbon storage and the amount of plant residues returned to the soil, the method and timing of biomass removal can significantly affect soil carbon pools. Eddy covariance systems monitored carbon dioxide fluxes over two pastures in Central Pennsylvania for two years. The first pasture was planted to mixed cool-season grasses in 1982 (Grass pasture) while the second was planted to alfalfa in 1995 (Alfalfa pasture) but by the time of the experiment also contained a significant cool-season grass component. Pastures were cut for hay or grazed 3 to 4 times per year. Flux measurements indicated that both pastures were significant carbon dioxide sinks in 2003, with the Alfalfa pasture taking up 959 and the Grass pasture 730 g CO2 m-2. However, in 2004, the Alfalfa pasture was a much smaller sink, accumulating only 166 g CO2 m-2. The Grass pasture became a source in 2004, losing 421 g CO2 m-2 to the atmosphere. When the biomass removed by grazing and haying was taken into consideration, both pastures remained sinks in 2003 with an average accumulation of 500 g CO2 m-2, but both pastures were sources in 2004, losing 315 g CO2 m-2 to the atmosphere. The summer of 2004 was cooler than 2003 while the rest of the year was generally warmer. Both years were relatively wet. Differences in environmental conditions were not sufficient to explain the large differences in fluxes between the two years. The timing of harvest events appeared to have the greatest impact on net carbon sequestration. Spring harvests that were timed to maximize forage quality and animal production had a negative effect on the carbon storage potential of the pastures. Harvesting right before the critical fall regrowth period also negatively affected carbon sequestration. Haying removed more biomass from the pastures than did grazing and, thus, had a more negative effect of carbon sequestration. Management practices that maximize animal productivity may not be the best for maximizing carbon accumulation.
Smith, James (USDA-Forest Service, Northeastern
Research Station, PO Box 640, Durham, NH, 03824; Phone: 603-868-7663; Email:
jsmith11@fs.fed.us)
Forest Carbon Growth and Yield Tables and Uncertainty
for U.S. Forest Types
J.E. Smith*, L.S. Heath
We have developed a set of forest carbon growth and yield tables useful as default estimators of the quantity of carbon sequestered in forest stands throughout the U.S. These tables are part of the USDA Forest Service forestry section of the 1605(b) voluntary carbon emissions and sequestration reporting program developed with the U.S. Department of Energy. A purpose of this program is to encourage reduction of the net release of greenhouse gasses to the atmosphere. To report forestry activities, a system to estimate the quantity of carbon sequestered in forest stands and harvested wood products throughout the United States is needed. The system must be accurate, relatively easy to use, credible, and economical. The tables were developed in response to these criteria; they provide default estimates for carbon sequestration projects in situations where more locally specific models or data are unavailable. Tables representing stand-level merchantable volume and various carbon pools as a function of stand age were developed for 70 forest types defined within 10 regions of the U.S. based on published models and data, including forest inventory data. Estimates reflect regional averages such as the relatively rapid accumulation in Southern pine plantations (up to 160 tons per hectare of carbon in trees by 25 years) or the large carbon pools in Douglas-fir in the Pacific Northwest (up to 400 tons per hectare of carbon in trees by 75 years). Separate equations were developed for afforestation and reforestation. Forest carbon pools include live trees, standing dead trees, understory, down dead wood, forest floor, and soil organic carbon. Carbon stock estimates are spatially heterogeneous in most forests. Much of the variability can be attributed to influences on stand growth and development such as site characteristics, weather, disturbances, or management practices. The tables are representative of regional averages. Therefore, the uncertainly in applying them to individual stands is partly attributable to forest heterogeneity and partly a reflection of uncertainty in the specific carbon estimators. We develop estimates of uncertainty in the specific carbon density estimators and apply these to both the carbon tables and stand-level inventory data to identify separate components of estimator-based uncertainty and variability in the application of the tables. Independent data sources are used to refine uncertainty estimates.
Sohi, Saran (Agriculture and the Environment
Division, West Common, Harpenden, Herts, AL5 2JQ, United Kingdom; Phone: +44
(0)1582 763133 ext.2665; Fax: +44 (0)1582 760981; Email: saran.sohi@bbsrc.ac.uk)
Accounting for Black C in the Modeling of
Soil Organic Matter Turnover
S.
Sohi *, J. Gaunt, H. Yates, J. Lehmann
According to recent estimates, black C is a much larger component of soil organic carbon (SOC) in typical agricultural soils than previously assumed. Since black C may also be the most stable form of organic C in the soil, the amount of black C in the soil must impact both on the bulk rate of soil C mineralization (turnover), and the extent to which a particular management intervention can alter SOC.
Simulation models that explicitly account for the impact and interaction of soil and environmental variables can assist in predicting the accumulation of C and its rate of turnover. Relevant, verifiable (i.e. measurable) pools of soil organic matter (SOM) provide the most robust basis for elucidating the underlying mechanisms. We have developed a model based around three measurable pools of SOM, which can be measured using a density-based fractionation procedure. The model has been optimized against measurements of C and N and isotope-tracers in several soils amended with isotope-labeled organic matter.
Until now our simulations have not accounted explicitly for the effect of black C on the dynamics of each pool. It seems unlikely that black C is characterized by a particular physical location within the soil matrix, and in order to account for the influence of black C using this model we have been developing methods to establish how black C influences C turnover and to establish the distribution of charcoal between each of the measured fractions. We will use the data gathered to assess the net impact of black C on soil C turnover.
Sommer, Allan (RTI International, 3040 Cornwallis Rd, Research Triangle Park,
NC, 27709; Phone: 919-316-3993; Fax: 919-541-6683; Email: sommer@rti.org)
Alternative Approaches to Quantifying and Reporting Carbon Sequestration Projects: The Case of Afforestation
A.J.
Sommer*, B.C. Murray
Project-based approaches to GHG mitigation in general and carbon sequestration in particular are gaining ground as a potentially effective means to reduce GHGs and achieve other environmental and economic objectives. In the U.S., voluntary programs such as the DOE 1605(b) and the California Climate Action Registry are encouraging the reporting of project-based actions. As a result, programs such as these and other overarching initiatives such as the World Resources Institute/World Business Council on Sustainable Development (WRI/WBCSD) are developing guidance for quantifying and reporting the contributions of these actions to GHG reductions.
A key technical issue in project quantification and reporting is the establishment of a project baseline, which estimates net GHG effects that would occur without the project. Baselines may be used to determine if project GHG reductions are additional to what would happen under business as usual. For the GHG protocols presented, to the extent that they address baseline-setting, consider two baseline-setting approaches, project-specific and performance standard. Our analysis evaluates usefulness of the two methods for evaluating carbon sequestration in agriculture, land use change, and forestry (AgLUCF). Given the spatially explicit nature of AgLUCF projects, the project-specific approach focuses on the characteristics of activities largely within project boundaries in determining the baseline. In contrast, the performance-standard uses regional information on the behavior of cohort groups to gauge what other landowners might do under conditions similar to the project.
We evaluate specific, though hypothetical, afforestation projects in the Lower Mississippi River Valley, USA, to “road test” the alternative protocols. Additionally we identify data requirements, assess the pros and cons of each approach, and quantify the difference in the potential GHG benefits generated under each approach for dealing with issues such as baseline-setting, treatment of leakage, and permanence. Comparing the quantification and reporting guidance of the protocols will identify key factors that affect the magnitude of reported sequestration benefits and the potential for misstating the GHG implications of a project under certain circumstances.
Sonne Hall, Edie (University of Washington, College of Forest Resources, Seattle, WA, 98195; Phone: 206-329-3569; Email: edie@u.washington.edu)
Greenhouse
Gas Emissions from Pacific Northwest Douglas-fir Forestry
Operations
E. Sonne Hall*
Most forest carbon assessments focus only on biomass carbon and assume that greenhouse gas (GHG) emissions from forestry activities are minimal. This study took an in depth look at the direct and indirect emissions from PNW Douglas-fir plantation forestry activities in order to support or deny this claim. GHG budgets for 408 “management regimes” were calculated using Life Cycle Assessment methodology. These management regimes were comprised of different combinations of three types of seedlings (P+1, 1+1, and large plug), two types of site preparation (pile and burn and chemical), transportation of seedling to field, 17 combinations of management intensity including fertilization, herbicide treatment, pre-commercial thinning (PCT), commercial thinning (CT), and nothing, and four different rotation ages (30, 40, 50, and 60 years). Normalized to 50 years, average direct GHG emissions were 3.68 metric tons CO2e/acre, which accounted for 82 percent of total GHG emissions from the average of 408 management regimes. Harvesting (PCT, CT, and Clear Cutting) contributed the most to total GHG emissions (1.8 tons CO2e/7500 cubic feet harvested timber), followed by pile and burn site preparation (0.8 tons CO2e/acre or 26 percent of total GHG emissions) and then fertilization (0.56 tons CO2e/acre or 18 percent of total GHG emissions). Seedling production contributed less than one percent of total GHG emissions when assessed per acre of planted timberland. Similarly, transportation of seedlings to field, chemical site preparation, and herbicide treatment each contributed about one percent to total GHG emissions. Emissions factors for each of the unit processes are presented separately and combined. The relative contribution of direct and indirect emissions was examined to see whether standard accounting procedures are acceptable. Finally, the relative contribution of each forest management decision is discussed and opportunities for reduction are identified. This paper will be followed with a second paper focused on changes in biomass carbon from different management alternatives, and putting biomass carbon and GHG emissions together to look at the total GHG budget from forestry activities.
Sperow, Mark (West Virginia University, Division of Resource Management, P.O. Box 6108, Morgantown, WV, 26506-6108; Phone: 304-293-4832 ext. 4475; Fax: 304-293-3752; Email: Mark.Sperow@mail.wvu.edu)
M. Sperow*, C. Bouquot
Significant
progress has been made to estimate the potential for terrestrial systems to
mitigate or off-set GHG emissions through carbon (C) sequestration. All potential terrestrial sinks need to be
analyzed, particularly those that may be attained with the least cost. Reclaimed mine land sites represent a C sink that
could be achieved at a lower cost than other terrestrial C sequestration
activities. Few analyses have captured
the C sequestration potential from mine reclamation activities. The objective
of this study is to analyze potential C sequestration gains in the soil, litter
layer, and above-ground biomass on mine
land sites in 7 central and northeastern states (IN, KY, MD, MI, OH, PA, and
WV) totaling nearly six hundred thousand hectares. Mine operators have been required
to reclaim coal mine sites by restoring the original contours of the landscape
and planting a vegetative cover since 1977.
Over 81% of the land mined since 1992 was in forest and nearly 10% in
pasture in 1992. Therefore, while the
analysis considers reclaiming mine sites to cropland and grass, the primary
focus is on C sequestration under forest and pasture. The C sequestration
potential on reclaimed mine sites is analyzed using estimates of the annual
rate of C change derived from published journal articles, conference
presentations, unpublished studies, and government publications. Existing studies generally do not provide
estimates of the carbon stock on mine land soils at the start of
reclamation. The IPCC method assumes
that “abandoned/degraded” land has lost 50% of soil carbon present under native
vegetation, which is the factor used in most of this analysis. In addition, soils in reclaimed mine sites
are assumed to be low activity (low clay content) mineral soils due to the
disturbance required during mining activities. The 1992 National Land Cover
Dataset (NLCD), State Soil Geographic information (STATSGO), and county
boundary GIS shape files are combined with specific data for mine lands in each
state in the study area to identify and spatially locate surface mine lands. Surface mine permit data in GIS format are
only available for Indiana, Kentucky, Ohio, and West Virginia. Mine areas for the remaining states, are
derived from the 1992 NLCD. In order to relate surface coal mine permit area
with the 1992 NLCD area, only surface mining permits active during and after
1992 are selected for analysis. With the
exception of Maryland, these data indicate that the 1992 NLCD and available GIS
data underestimate the extent of mine lands in the study region. The analysis
shows carbon sequestration is largest by reclaiming all mine land in the study
region to forest (1.0-2.7 Tg C yr-1) with most
C from above-ground biomass (0.7-1.1 Tg C yr-1) and soils (0.4-1.7 Tg C yr-1).
Reclaiming all mine land in the study area to forest provides a biophysical
potential of sequestering 21-54 Tg C over twenty years. Mine land in West Virginia and Pennsylvania
provide the largest C sequestration potential from forest (10.7 and 5.1 Tg C
respectively) over twenty years.
Reclaiming mine land in Indiana and Ohio to cropland provides 2.2 Tg C
over twenty yeas. This is less than the 6.9 Tg C that could be accumulated over
twenty years if land is reclaimed to forest.
Staggenborg, Scott (Kansas State University, Dept. of Agronomy, 2004 Throckmorton Hall, Manhattan,
KS, 66506; Phone: 785-532-7214; Fax: 785-532-6094; Email: sstaggen@ksu.edu)
Intensifying No-till Cropping Systems Increases Soil Carbon Levels: A Modeling Approach
S.A. Staggenborg*, C.W. Rice, R.G. Nelson, J.R. Williams
Cropping
systems research faces numerous challenges, one of which is the time required
to conduct field experiments. Soil carbon research is faced with many of the
same challenges since changes are subtle and require long-term monitoring. Crop
simulation models represent a tool to address these challenges as often the
only limit is measured weather data at a given location. The objective of this
research was to evaluate the impact of intensifying crop rotations on soil
carbon dynamics across Kansas through a crop and soil simulation framework. The
two cropping systems, a traditional and an intensified rotation were simulated
at three locations in Kansas. Brown, Reno and Greeley counties, in eastern,
central and western Kansas respectively, were selected as they represent the
range of growing conditions experienced in the state. The dominant crop
rotations are corn-soybean in Brown county, continuous wheat in Reno county,
and wheat-fallow in Greeley county. Simulated intensified rotations were
soybean-corn-wheat-double crop soybean-corn in Brown county, wheat-grain
sorghum in Reno county, and wheat-sorghum-fallow in Greeley county. These
rotations were simulated using CERES-Maize, CERES-Sorghum, CERES-Wheat and
CROPGRO-Soybean in the DSSAT framework from 1960 to 1990 using measured weather
data from each site. Grain and dry matter yields were used as input into ROTH-C
26.3, a soil carbon simulation model. Three soils from each county were used in
the simulations and were selected based on cropland acres according to the NRCS
soil survey. No-till and conventional till systems were simulated by modifying
the amount of dry matter returned to each system and adjusting yields for the
tillage systems in Greeley county. At all three sites, intensifying the crop
rotation increased soil carbon levels compared to the conventional rotation. In
Brown county, intensifying the corn-soybean with wheat and double crop soybeans
increased ending soil carbon levels 35%. This occurred largely as a result of
reducing fallow periods and replacing soybean, a low carbon contributing crop,
every other year with wheat, a high carbon contributing crop. In Reno county,
the inclusion of grain sorghum in an annual wheat rotation increased final soil
carbon only 6% compared with continuous wheat. This is not unexpected as grain
sorghum and wheat are similar in contributing carbon into a system, so the only
advantage to adding grain sorghum is the elimination of fallow periods,
especially during the summer months. In Greeley county, adding grain sorghum to
a wheat-fallow cropping system increased final soil carbon levels comparatively
by approximately 50%. However, regardless of rotation used, soil carbon levels
declined over the 30 year simulation period compared with the initial soil
carbon levels. This loss in soil carbon is attributed largely to the extended
fallow periods experience in both cropping systems along with the low
productivity levels experienced in this semi-arid environment. The largest
impact on soil carbon levels after 30 years, from a management perspective was
the adoption of no-till systems. In all three environments and across soil
types, the simulated no-till system resulted in soil carbon levels more than
twice those simulated in the conventionally tilled system. These results
illustrate the potential of modeling crop and soil systems to study management
impacts on soil carbon and support field work that indicates that intensifying
crop rotations, eliminating fallow periods and the adoption of reduced or
no-till production practices increase soil carbon levels with the final levels
being dictated by the growing conditions.
Steinbach, Haydée Sara (Univ. of Buenos Aires, Argentina, Av. San Martin 4453, Buenos Aires, C1417DSE, Argentina; Phone: 05411-45248080; Fax: 05411-45248076; Email: steinbac@agro.uba.ar)
Changes in Soil Organic Carbon Contents and Nitrous Oxide Emissions after Introduction of No Till in Pampean Agroecosystems
H.S. Steinbach*, R. Alvarez
During the last decade no till use has widespread in the Argentine Pampas. Around 50% of agricultural lands are cropped under no till nowadays. Many experiments have been performed to evaluate no till effects on soil organic carbon (SOC) stocks or N2O emissions but results have not been integrated. Consequently, knowledge about the effect of no till on SOC cannot be generalized to non-experimental sites. Our objective was to generate equations suitable for predicting no till effects on SOC and denitrification in the Pampas and to estimate the potential of no till to sequester carbon and mitigate the global warming effect. A review of published results from tillage experiments conducted in the Pampas during the last 20 years was performed. On an equivalent mass basis 42 paired data from comparisons of no till vs. plow till (mould board plow or disk plow), 18 paired data from comparison of no till vs. reduced till (chisel plow or harrow disk), and 20 paired data from comparisons of reduced till vs. plow till were obtained. Twenty-six denitrification data were also obtained. Data were analyzed by paired t test and linear regression methods. Under no till SOC increased 2.76 t ha-1 (P = 0.01) in relation to tilled systems, but no differences were detected between plow and reduced till. Climate, soil texture or rotation did not affect the magnitude of carbon sequestration under no till. A linear regression model could be used for predicting SOC under no till, using SOC under tillage (plow or reduced) as independent variable (R2 = 0.94, P less than 0.01). The model predicted a relative higher increase of SOC in areas of low organic matter level. Consequently, the impact of introducing no till would be higher in the semiarid portion of the Pampas than in the humid part. SOC increases, due to the introduction of no till, ranged from 15% in the west semiarid portion of the Pampas to 5% in the humid west. The conversion of the whole pampean cropping area (26 Mha) to no till will produce a carbon sequestration of 74 Mt C. This carbon sequestration is equivalent to the double of the annual carbon emissions from fossil fuel consumption of the country. The sequestration of carbon in soils under no till would be finish about 10 years from introduction. For wheat and corn, two of the main crops of the Pampas, N2O emissions are greater under no till during the initial stages of growth. It was estimated a mean increase of 1 kg N ha-1 yr-1 emitted by denitrification under no till for the common double crop wheat/soybean-corn-soybean rotation. The emission of N2O will overcome the mitigation potential of no till due to carbon sequestration in about 40 years and thereof no till will produce to global warming.
Subak, Susan (ISSE, NCAR, P.O. Box 3000, Boulder, CO,
80307; Phone: 1-303-497-8117 ; Fax: 1-303-497-8125 ; Email:
subak@ucar.edu)
A Comprehensive Environmental and Economic Assessment Method Applied to the Southwest Michigan Greenhouse Gas Mitigation Cropping Experiment
S. Subak*
A comprehensive assessment of net environmental and economic benefits of alternative cropping systems compared with conventional tillage is estimated for one site in southwestern Michigan. The cropping systems considered include conventional tillage, no-tillage, low-input with legume cover and an organic system with legume cover, at a site located at the Kellogg Biological Station, which is a Long Term Ecological Research site. In a study published in Science in 2000, Philip Robertson and colleagues reported their estimates of the different Global Warming Potentials related to direct and indirect carbon dioxide, methane and nitrous oxide emissions from these different cropping systems considering ten years of emissions monitoring. The present study builds on the previous greenhouse gas analysis by presenting a toxicity index for the chemical loadings on the different cropping systems related to applications of herbicides and pesticides. In addition, this study considers the nitrogen loadings associated with the different cropping systems. These three environmental effects -- greenhouse gas emissions, nitrogen loadings, and chemical loadings -- are compared with estimated economic benefits based on conventional calculations of direct input costs, crop value and yields. In this example, the three alternative cropping approaches had lower environmental and economic costs than the conventional tillage approach. While the no-tillage approach was associated with the greatest reductions in greenhouse gas emissions, the other two alternatives were associated with reduced input costs and reduced loadings of other pollutants.
Subramanian, Senthil Kumar (Dept. of Crop & Soil Sciences, Michigan State University, East Lansing, MI, 48823; Phone: 517-980-2741; Fax: 517-355-0270; Email: subram20@msu.edu)
Quantifying Soil Carbon Using NIR spectroscopy: A Study on Its Consistency at Different Soil Carbon Levels
S.K. Subramanian*, A.N. Kravchenko, X. Huang, J. Qi
Quantitative assessment of soil carbon has gained increased interest in recent years, since such information helps farmers and land managers in developing strategies for increasing soil sustainability and productivity and helps researchers to find out the best land use practices that sequester more carbon per land unit. Deriving such information through standard procedures of soil sampling and laboratory analyses is expensive, time-consuming, and labor-intensive. The recently developed methods of Near-Infrared (NIR) spectroscopy have potential in augmenting the current procedures by reducing the time and the cost involved. However, it has been reported that accuracy of soil carbon prediction by NIR might vary at different levels of soil carbon. The objective of our study is, thus, to assess the consistency of soil carbon predictions using NIR under different soil carbon levels. A set of 1,200 samples has been collected from the Long Term Ecological Research site (LTER) at the Kellog Biological Station, MI. The samples were analyzed for total carbon/nitrogen contents and spectral measurements for each sample was collected in the laboratory conditions with analytical spectral device (ASD). First, we used a portion of the samples to test the statistical significance of employing NIR in soil carbon prediction across all observed levels of carbon (from <0.8 to >3.0 %) based on principal component and regression analyses, and found the regression model to be significant (r2=0.82). Then, we segregated the samples into different groups based upon the soil carbon values (e.g., <1.0%, 1.0-1.5%, 1.5-2.0%, 2.0-2.5%, 2.5-3.0%, >3.0%). The comparisons of how accurate the NIR predictions are in every soil C group will be presented and discussed. The results will help us in assessing the reliability of NIR spectroscopy in soil carbon prediction and thereby will provide the researchers and decision makers with an idea on how far such predictions can be relied on.
Tan, Ivy (Cornell University, 151 Dryden Road #228,
Ithaca, NY, 14850; Phone: 607-351-3917; Email: it36@cornell.edu)
I.Y.S. Tan*, H.M. Van Es, J.M. Duxbury, J.J. Melkonian, L.D. Geohring, R.R. Schindelbeck, D. Hively
Greenhouse gas emissions from nitrous oxide (N2O) are due in part to N inputs on agricultural land that are lost through the nitrification and denitrification processes. Earlier studies have shown that late spring is a critical time period compared to other seasons, because high soil nitrate levels are susceptible to leaching and denitrification. This is especially the case with maize production when the entire seasonal fertilizer needs have been applied at planting. Quantitative information on N2O emissions as affected by soil type and crop management practices is scarce, especially with regards to tillage and timing of N application. This study examined the effects of tillage (no-till, plow) and fertilizer timing (at planting, sidedress) on two soil types (a glacio-lacustrine Muskellunge clay loam and a Stafford loamy fine sand), each with a cropping history of orchardgrass and maize on N2O emissions and NO3-N leaching potential as a result of 50-mm precipitation. N2O emissions were measured daily over a period of a week. N2O emissions were highest on the second day after precipitation for all treatments. N2O losses were significantly higher on the clay loam compared to the loamy sand. Early fertilization at planting under no-till on previous grass resulted in large N2O emissions, with a cumulative N2O loss of 4.4 kg N/ha greater than late fertilization. Similar N and tillage treatments on previous corn, however, had a relatively smaller emission, with a cumulative N2O loss of 2.3 kg N/ha greater than late fertilization. Small N2O emissions were observed on plots under plow-till treatments. Early fertilization under plow-till on previous grass emitted 0.96 kg N/ha greater cumulative N2O loss than late fertilization, while early fertilization under plow-till on previous corn resulted in 0.82 kg N/ha greater cumulative N2O loss than late fertilization. These results show that the amounts of N2O emitted vary significantly among tillage treatments and timing of N application, and that no-till and early fertilization increase N2O emissions. Although conservation tillage encourages sequestration of soil C, the focus on N management is equally, and perhaps more, important. A balance is needed in adopting best management practices in order to minimize total greenhouse gas impacts.
Tan, Zhengxi (South Dakota State University-Brookings, EROS Data Center, 47914 252nd St., Sioux Falls, SD, 57198; Phone: 605-594-6903; Email: ztan@usgs.gov)
Soil
Organic Carbon Budget as Related to Land Use History in the
Z.X. Tan*, S. Liu, C.A. Johnston, J. Liu, T.R. Loveland
The strategies for mitigating global greenhouse effect need to understand soil organic carbon (SOC) dynamics and driving factors at both spatial and temporal scales, which is usually challenging due to limitation in data and approach. This study was conducted to characterize the SOC dynamics associated with land use change history in the Northwestern Great Plains Ecoregion. A sampling framework (40 sample blocks of 10km x 10km randomly located in the Ecoregion) and the General Ensemble Biogeochemical Modeling System (GEMS) were used to quantify the spatial and temporal variability in the SOC storage from 1972 through 2001. The results indicate that the C source and sink coexist in the study area and overall SOC storage in the top 20 cm depth over the 30 years increased by 3.93 Mg/ha. About 17.5% of the area was evaluated as a C source at a rate of 0.122 Mg C/ha/yr. The spatial variability of total SOC storage was determined by the dynamics of both slow and passive fractions but the temporal variation depended on slow fraction only. The magnitude of SOC budget at the block scale was significantly related to either grassland areal proportion positively or cropland fraction negatively. It was concluded that C sink was generally associated with grassland use and C source with cropland but their strength depended on antecedent SOC contents and land use change history.
Thomson, Allison (Joint Global Change Research Institute, 8400 Baltimore Ave., Ste 201, College Park, MD, 20740; Phone: 301-314-6750; Email: allison.thomson@pnl.gov)
A.M. Thomson*, R.C. Izaurralde, M.P. McClaran, S.P. McLaughlin, N.J. Rosenberg
Semi-arid
rangelands cover a large area in the US southwest and have changed extensively
over the past century due to human influence. Although soil carbon content is
low, a large area of land (3.8 million ha) in Arizona is managed by the State
Lands Department. Therefore, if a
management change was found to increase soil C and implemented across the
region, it could result in significant amounts of C sequestration. First we must understand the physical
potential for soil carbon sequestration in these rangeland ecosystems, how it
is influenced by management practices, and how it has responded to the changes
of the past century. Research on range
management and ecosystem composition has been conducted for over 100 years,
however analysis of soil properties has not been included in this
research. By reconstructing the
management and vegetation history in a process-based ecosystem model we can
examine the impact on soil properties.
We can then use that knowledge to project the potential of these
semi-arid rangelands to act as a source or sink of soil C in response to
management practices and climate variability and change. Like many semi-arid grasslands around the
world, southeastern Arizona has experienced woody encroachment by velvet
mesquite (Prosopis velutina). Mesquite are a physical impediment to
grazing and also reduce the grass productivity of a pasture, therefore mesquite
removal treatments have been attempted by clear-cutting and herbicide
application. For this study, control and
treatment pastures on the Santa Rita Experimental Range (SRER) were selected
for biomass measurements and soil sampling. Livestock grazing has also evolved
over the past century as unsustainable year-round grazing has been replaced by
rotational grazing systems and intensive grazing systems in order to maintain
productivity of the grasslands. The intensive
grazing system referred to as holistic resource management (HRM) has been
applied for the past 20 years to a private ranch adjacent to conservation land
– the Audubon Appleton-Whittell Research Ranch (AWRR). Biomass measurements and soil sampling were
also conducted at these sites to assess the influence of intensive grazing and
rest from grazing on lands which have not experienced mesquite
encroachment. The patterns of mesquite
encroachment and control and the details of grazing history are reconstructed
in the simulation model EPIC (Environmental Policy Integrated Climate), a
process based model which operates on a daily time step and simulates biomass
production and soil C dynamics. Soils
are initialized using field values for sites approximating the history of land
use from 1900 and the model simulation of grass and mesquite biomass is
calibrated using field data. The
different management practices are simulated for the next 100 years. The impact of nitrogen-fixing mesquite
encroachment on soils is positive and significant. While the management treatments (clear cut in
1930’s and herbicide in 1960’s) reduce mesquite influence, the impact on
biomass does not last more than a decade.
The model illustrates that grazing systems do have an impact on soil C,
with variation in response due primarily to interannual climate variations. By
reconstructing the past century of biomass and soil dynamics in the simulation
model, we establish a basis for evaluating soil C sequestration potential and
considering soil C in the development of land management plans for the region.
Tian, Hanqin (Auburn Univ., School of Forestry and
Wildlife Sciences, Auburn, AL, 36849; Phone: 334-844-1059; Fax: 334-844-1084;
Email: tianhan@auburn.edu)
H. Tian*, H. Chen, C. Zhang, M. Liu, S. Pan, J.M. Melillo, D.W. Kicklighter, B. Felzer
Land ecosystems in the southeast US are thought to be currently functioning as the largest carbon sink among the six major bioclimatic regions of the conterminous United States. Inverse-and inventory-based estimates on the carbon sink do not identify the mechanisms responsible for the carbon sink. Many of the major factors (and complex interactions) that affect this carbon sink are operating concurrently in the southeastern ecosystems. In this study, we intend to examine how ecosystem carbon storage has changed as a result of multiple stresses and interactions among those stresses including land-cover change, climate variability, atmospheric composition (carbon dioxide and tropospheric ozone), precipitation chemistry (nitrogen composition), and natural disturbances such as fire using estimates of carbon fluxes and storage from factorial simulation experiments with the Terrestrial Ecosystem Model (TEM) in conjunction with remotely sensed and field data. Our analysis suggests that the net carbon exchange of terrestrial ecosystems with the atmosphere in this region varied substantially from a source of 230g C/m2 to a sink of 325 g C/m2. Forest recovery after cropland abandonment and natural disturbances have resulted in an carbon uptake, but rapid urbanization and rising tropospheric ozone pollution have led to a significant reduction in carbon storage in the southeast.
Townsend, David (Premium Standard Farms, Inc., 805 Pennsylvania Ave,
Kansas City, MO, 64105; Phone: 816-843-1471; Email: dave.townsend@psfarms.com)
D. Townsend*, M. Gabris
Premium Standard Farms is the second largest hog producer in the United
States and a member of the Chicago Climate Exchange (CCX). Through our membership at CCX we have
committed to reducing our company wide greenhouse gas emissions. We have two anaerobic digester systems near
Dalhart, Texas that capture methane and burn it for process heat. We have aggregated carbon credits from these
systems and are beginning to trade them at CCX.
In addition, we are constructing a large digester system in Missouri
that will capture methane and use it to dry manure to a granular fertilizer
(Crystal Peak process). We plan to
market carbon credits from this project as an additional revenue source to help
finance the project. We have encountered
and worked through numerous technical, procedural and accounting challenges in
determining our baseline emissions and obtaining third party verification of
our digester methane production.
Updegraff, Karen (South Dakota School of Mines & Technology, Institute of Atmospheric Sciences, Rapid City, SD, 57701; Phone: 605-394-1989; Fax: 605-395-6061; Email: Karen.Updegraff@sdsmt.edu)
K. Updegraff*, P. Zimmerman, D. Kliche, W.J. Capehart, M. Price
The Big Sky Regional Partnership has prepared an assessment of carbon storage potential on agricultural lands in a 3-state region (SD, MT and ID). The assessment is based on climate-zone level modeling using the CENTURY biogeochemical model, and provides information on current rates of soil carbon change as well as potential rates given various management assumptions. While all three states are currently net carbon sinks with respect to agricultural soils, Montana manifests the highest total rates of net SOC increase due largely to its extensive areas of cropland and rangeland. In addition, it has the largest current CRP enrollment (3.4 m acres). South Dakota has by far the largest area of cropland under no-till management as well as the largest area of harvested cropland. The greater importance of corn and soybeans (as opposed to winter wheat) in South Dakota agriculture give it the highest potential for enhanced carbon uptake due to increased no-till adoption. Idaho has the least potential for agricultural sink enhancement, due largely to its more limited area of harvested cropland and rangeland.
Vargas, Rodrigo (University of California-Riverside, Center for Conservation Biology, University Laboratory, Riverside, CA, 92521; Phone: 951-827-6314; Fax: 951-827-4625; Email: rvarg001@student.ucr.edu)
Soil Embedded Networked Systems for Studying Soil Carbon Dynamics: The A-MARSS Project
R. Vargas*, M.F. Allen, M. Hamilton, W. Swenson
The role of soil microorganisms is still a black box in global change research because soil processes are difficult to quantify in space and time. We collaborate with the NSF S&T Center for Embedded Networked Sensing (CENS), and are developing the Automated-Minirhizotron and Arrayed Rhizosphere-Soil Sensors (A-MARSS). A-MARSS is a wireless array technology to study mycorrhizal and has applications to soil carbon dynamics. The goal is to spatially measure moisture, temperature, nitrate, and CO2, coupled to an automated camera to observe roots and mycorrhizae in soils. Solid-state CO2 probes coupled with dielectric soil moisture and temperature sensors are being monitored to study soil CO2 concentration and flux at three different depths. This sensor array has shown significant relationships between CO2 concentration in soils, soil temperature and soil moisture. The sensors array, their spatial distribution and ongoing results will be presented. For a better understanding of soil carbon dynamics high sampling resolution data is required. Soil embedded networked systems is an alternative tool to obtain large amount of data and opens new possibilities for environmental modeling. The bottom line of this presentation is to describe small-scale spatial and temporal variability of CO2 concentration in soils by using soil embedded networked systems
Veenstra, Jessica (University of California-Davis, TB13, One Shields Ave., Davis, CA, 95616; Phone: 530-754-6185; Email: jjveenstra@ucdavis.edu)
Changes in Aggregate-Protected Carbon with Conservation Tillage and Cover Cropping
J. Veenstra*, W. Horwath, J. Mitchell,
Conservation tillage (CT) and cover cropping are sustainable agricultural practices that may provide solutions for California’s declining soil, air and water quality. These practices can increase soil organic matter, reduce dust production conserve water and increase soil C. We looked at changes in total soil C and particulate organic matter (POM) within three physical fractions: free POM, microaggregate protected POM, and mineral associated organic matter. With the decrease in soil disturbance under CT and increased C inputs with cover cropping, we expect microaggregate protected POM to increase in both the CT and the cover crop treatments over the long term. Increases in microaggregate protected POM may indicate future C storage. Initial inspection of soil C numbers suggest that cover cropping increases total soil C in both CT and standard tillage on the order of 4500 kg C/ha in the top 30 cm over a 4-year period. In the CT treatments, the increase occurred in the surface 15 cm, while in the standard tillage treatments, it was distributed throughout the top 30 cm. In the treatments without cover crops, there was no change in soil C in the 0-15 cm depth and an overall loss in the 15-30 cm depth, ~1000 kg C/ha in standard tillage and ~2000 kg C/ha in CT. In dry hot irrigated systems, cover cropping was more important for soil C accumulation than tillage practice.
Venterea, Rodney (USDA-ARS, 439 Borlaug Hall, University of Minnesota, St. Paul, MN, 55108; Phone: 612-624-7842; Fax: 651-649-5174; Email: venterea@umn.edu)
Nitrous Oxide and Methane Emissions Under Varying Tillage and Fertilizer Management
R. Venterea*, M. Burger, K. A. Spokas
Reduced
tillage is being examined as a means of enhancing soil carbon and mitigating
greenhouse gas (GHG) emissions. There is
relatively little information regarding tillage effects on emissions of nitrous
oxide (N2O) and methane (CH4), which have higher global
warming potentials than carbon dioxide (CO2). We used chambers to
measure N2O and CH4 fluxes in plots maintained under
differing tillage treatments since 1991.
Emissions of N2O following broadcast urea (BU) application
were higher under no till (NT) and conservation tillage (CsT) compared to conventional
tillage (CT). In contrast, following
anhydrous ammonia (AA) injection, N2O emissions were higher under CT
and CsT compared to NT. Emissions
following urea ammonium nitrate (UAN) application did not vary with
tillage. Total growing season non-CO2
GHG emissions were dominated by N2O, and were equivalent to soil C
losses of 0.07-0.50 Mg C ha-1
y-1. Uptake of CH4 during the drier of
the two seasons (2003) was two to three times higher than during 2004. Emissions of N2O from AA-amended
soils exceeded emissions from the UAN and BU treatments. This study demonstrates that tillage effects
on N2O emissions depend on fertilizer management and that non-CO2
GHG emissions can contribute substantially to the total GHG budget of
agro-ecosystems in the upper mid west
Venteris, Erik (Ohio Division of Geological Survey, Petroleum Geology Group, Columbus, OH, 43229; Phone: 614-265-6459; Fax: 614-447-1918; Email: erik.venteris@dnr.state.oh.us)
Impact of Soil Redistribution on the Mass Balance of
Soil Organic Carbon in Hummocky Glacial Topography,
E.R.Venteris*, G.W. McCarty, J.C. Ritchie, T.E. Fenton, T.C. Kaspar
The Soil Organic Carbon (SOC) budget is a function of the balance between vegetative production, oxidative losses, and mass transport by water/ tillage. Models for spatio-temporal prediction are needed that account for mass transport processes in a realistic manner. Past work has concentrated on water erosion but has neglected water deposition and soil transport by tillage. Understanding these processes is essential to successful numerical modeling and for the placement of sites to monitor SOC changes for carbon accounting. To better understand and model these processes, two high-resolution (25 m) soil sample grids were collected on separate agricultural fields (chisel ploughed, corn soybean rotation). SOC and Cs-137 (to model erosion/deposition) were measured for each soil sample point. Five meter resolution data were collected with GPS to provide topographic information (DEM). A unique characteristic of the study fields is that they contain small (100 m from bottom to top, 5 meters relief) closed depressions. Hence the mass balance of soil transport should sum to near zero. Mass balance results for four studied depressions were -2.37, -4.89, 0.941 and 0.9 Mt/ha/year. These numbers are within potential losses/ gains from wind erosion (±2.5-5 Mt/ha/year). Erosion/deposition models based on Cs-137 concentration (Walling and He method) are giving reasonable results and do not show systematic bias towards erosion or deposition. The site is especially useful for the calibration of spatio-temporal soil and carbon erosion/deposition models as large mass imbalances would expose biases in these models (RUSLE, WATEM, etc.). These results also demonstrate the need to take into account landscape redistribution of carbon when using the benchmark approach to assess temporal changes in SOC inventory.
Verma, Shashi. B. (University of Nebraska-Lincoln, School of Natural Resources, Chase Hall, Lincoln, NE, 68583-0728; Phone: 402- 472-6702; Fax: 402- 472-6614; Email: sverma1@unl.edu)
S.B.Verma *, A.E. Suyker, G.G. Burba, T.J. Arkebauer, D.T. Walters, A. Dobermann, K.G. Cassman, B. Amos, H. Yang, K.G. Hubbard, A.A. Gitelson, E.A. Walter-Shea, D. Ginting
Carbon dioxide exchange was quantified in the dominant maize-soybean cropping systems of the USA Corn Belt employing year-round tower eddy covariance flux systems during 2001-2004. Flux tower measurements were made in production-scale fields for three cropping systems: (a) irrigated continuous maize, (b) irrigated maize-soybean rotation, and (c) rainfed maize-soybean rotation. We will present results on net ecosystem exchange (NEE) for the initial three years of this study to address the following questions: (1) how does the seasonal and annual carbon dioxide exchange of maize compare with that of soybean? (2) What is the impact of irrigation, versus dryland farming, on the carbon dioxide exchange of these crops? (3) How does the annual carbon dioxide exchange of continuous maize system compare with a maize-soybean rotation? Crop and soil management in each of these systems followed progressive, best management practices and our results provide relevant information on C sequestration of these systems.
Walsh, Margaret (ICF Consulting, 1725 I St. NW Suite
1000, WashingtonDC, 20006; Phone: 202-862-1580; Fax: 202-862-1144; Email:
mwalsh@icfconsulting.com)
Agricultural Soil N2O Emissions in the US Greenhouse Gas Inventory: A Comparison of Methodologies
M.K. Walsh*, S.J. Del Grosso, T. Wirth
The Inventory of U.S. Greenhouse Gas Emissions and Sinks has until recently relied on standard IPCC default methodologies to estimate N2O emissions from agricultural soils. For the most recent evaluation, however, the process-based biogeochemical simulation model DAYCENT has been applied to the portion of emissions resulting from soils cropped with major crop types. The differences in the approaches, inputs, results, and diagnostic variables (such as a comparison of IPCC’s emission factor with the effective emission factor as derived by DAYCENT) are presented, to provide an evaluative overview of emission estimation methodologies. The results provide mixed implications to future revisions of inventory methodologies.
Walters, Daniel (University of Nebraska-Lincoln,
Dept. of Agronomy and Horticulture, 261 Plant Sciences, Lincoln, NE,
68583-0915; Phone: 68583-0915; 402-472-1506; Email: dwalters1@unl.edu)
Full C-Cost Accounting and Global Warming Potential of Irrigated and Rainfed Maize-Based Cropping Systems that Produce Renewable Energy from Grain
D.T. Walters*, D. Ginting, K.G. Cassman, H. Yang,
S.B. Verma, A. Dobermann, M. Schroeder
The potential of modern maize production systems to mitigate anthropogenic greenhouse gas emissions depends on the ability to sequester more C in soil than is consumed in fossil fuel use or lost as nitrous oxide and methane. Full C-cost accounting quantifies the net balance of CO2-C equivalents in terms of soil C sequestration versus the embodied CO2-C emission ‘costs’ for all inputs used in crop production (seed, fertilizer, pesticides, and fossil fuels consumption for mechanical operations, transportation, and irrigation). This approach also accounts for the more potent global warming potential of N2O and CH4 versus CO2 to estimate the net effect on global warming potential. Such an analysis was performed for three production-scale no-till cropping systems: (a) irrigated continuous maize, (b) irrigated maize-soybean rotation, and (c) rain fed maize-soybean rotation. Over a 3-year period, net ecosystem exchange was measured by eddy covariance flux towers, fluxes of N2O and CH4 at the soil surface were monitored throughout the year, and applied inputs and energy use in field operations and irrigation were recorded. A full C-cost accounting will be reported for these three cropping systems based on a field-level analysis. In addition, the full C-cost accounting will be extended to include bioenergy fuel production using the harvested corn grain to produce ethanol and soybean seed for biodiesel fuel with consequent impact on the overall GHG emission balance and global warming potential.
Werts, Scott (Johns Hopkins University, Dept. of Earth and Planetary Sciences, 113 Olin Hall, 2400 N. Charles St., Baltimore, MD, 21218; Phone: 410-516-7521; Fax: 410-516-7933; Email: swerts@jhu.edu)
Determining Amounts of Carbon Loss and Change in Carbon Isotope Values from Soils Due to Biomass Burning
S.P.Werts*, A.H. Jahren
Quantifying carbon emissions from the burning of above ground biomass has long been studied and considered a major source of greenhouse gases to the atmosphere. In most studies, however, carbon emissions from soil due to these burning events is not considered even though these soils often contain three times the amount of carbon as the biomass contained above it. The amount of heat applied to soils can vary greatly during burning events as temperatures of less than 100˚ C to over 700˚ C have been recorded. Here we explore a laboratory-based approach to determine the amount of Corg lost and changes in d13C values at different temperatures. Two soils that differ in some physical and chemical properties were selected from a location in a deciduous hardwood forest in the Appalachian Mountains of Western Maryland for analysis in the laboratory. Corg losses of 20% or greater were seen in all horizons between 200 and 400˚ C with 95% organic materials being liberated at 400˚ C. Past 200˚ C, the levels of Corg lost for each horizon are within 12% of each other indicating a high correlation with temperature. The Dd13C from 200 to 400˚ C are also dramatic as there is an overall enrichment of between 2.3 and 3.5%. Further analysis indicates that amounts of organic material and clay present in the soils have no influence on the levels of Corg loss or post-burn d13C values in dry soil.
White, John (ARS, Beltsville Agricultural Research
Center,10300 Baltimore Avenue, BLDG 306, BARC-East, Beltsville, MD, 20705; Phone:
301-504-8101; Fax: 301-504-8162; Email: whitej@ba.ars.usda.gov)
Soil Carbon Dioxide Flux in Conventional and Organic Cropping Systems: Comparison of Measurement Methods and Relationship with Soil Moisture
J.W. White*, M.A. Cavigelli, L.J. Sikora
Accurate measurement of soil
carbon dioxide (CO2) flux is necessary to evaluate the effects of
cropping systems on global warming potential and to provide accurate estimates
of carbon (C) budgets. Soil CO2
fluxes, soil temperature and volumetric water content (VWC) were measured in no
till, chisel till and organic cropping systems in order to compare two flux
measurement methods and to investigate the effects of soil moisture on CO2
flux under different management regimes.
Static versus dynamic closed chamber methods, both using infrared gas
analysis to measure CO2 concentrations, were compared in the no till
and organic systems. Flux measurements
from the chisel till system were made with static chambers only. Cumulative CO2 flux by the static
method for the period April to December was highest in the organic system
(12.88 ± 1.10 g CO2 (m2*hr)-1), intermediate
in the chisel till system (10.38 ± 0.63 g CO2
(m2*hr)-1),
and lowest in the no till system (8.62 ± 0.55 g CO2 (m2*hr)-1). In comparison, cumulative CO2 flux
by the dynamic method for the period April to October was 20.12 ± 0.97 g CO2
(m2*hr)-1 in the organic system and 13.32 ± 0.19 g CO2
(m2*hr)-1 in the no-till system. While both methods described the same overall
patterns of CO2 flux over time, the dynamic chambers gave almost
consistently higher readings than the static chambers (static method =
0.4584(dynamic method) + 0.1278). The
discrepancy between methods may be due to a greater reduction in the diffusion
gradient of CO2 using the static versus the dynamic method since
chambers were covered for a slightly longer period of time using the static
method (12 min) than using the dynamic method (less than or equal to 2
min). We investigated the influence of
soil moisture on CO2 flux standardized to 25oC using data
collected by the dynamic method and found that no till system soils responded
differently than organic system soils to changes in soil moisture. Maximum CO2 flux occurred at 20.0%
VWC (~38.4% water filled pore space (WFPS)) in the organic system while it
occurred at 27.6% VWC (~52.5% WFPS) in the no till system. Also, at soil moisture concentrations lower
than 29.1% VWC, CO2 flux was significantly greater (P less than
0.05) in the organic system than in the no till system. There were no differences in CO2
flux between these two systems at moisture contents between 29.2% and 39.7%
VWC. At soil moisture contents of 39.8%
VWC and above CO2 flux was significantly greater (P less than 0.05)
in the no till system. Greater CO2
flux under organic management is likely due to the greater availability of
labile C. We found significantly greater
(P less than 0.05) concentrations of dissolved organic C (DOC) in the organic
system soil (62.2 ± 6.23 mg DOC kg-1) than in the no till system
soil (41.0 ± 3.43 mg DOC kg-1).
The different soil moisture levels at which maximum CO2 flux
occurred in the two systems is likely due to significantly greater (P less than
0.001) soil porosity, possibly attributable to an
increase in the proportion of macropore space, in the no till system soil
(0.48 ± 0.0039) than in the tilled organic system soil (0.42 ± 0.0085). Thus, as soil moisture increases beyond 20.0%
VWC, gas exchange is limited in the organic system soil. In contrast, gas exchange is not limited in
the no till soil until moisture reaches 27.6% VWC.
White, Paul (Kansas State University, 2004A
Throckmorton Hall, Manhattan, KS, 66506; Phone: 785-532-7106; Email:
pmwhite@ksu.edu)
Carbon and Microbial Community Dynamics After Addition of 13C-Labelled Grain Sorghum Residue
P.M. White*, C.W. Rice
A greater understanding of the terrestrial C cycle will benefit climate change models and add to our knowledge of agriculture’s potential in greenhouse gas mitigation. A field microcosm study was conducted in no-tillage and conventional tillage grain sorghum during 2004 growing season. The 5 cm diameter x 15 cm deep polyvinyl chloride (PVC) microcosms were amended with 0.5% by weight 13C-labelled grain sorghum residue that was grown and labelled the previous winter in the growth chamber. The empty microcosms were hammered into the soil and carefully removed as to not disturb the surrounding soil. For conventional tillage, the soil was removed from the microcosm and the residue was incorporated before returning the soil to the microcosm. For no-tillage the soil was not removed and the residue was placed on the soil surface. Non amended controls were also included for each tillage practice. The ends of the microcosms were then covered with nylon netting and returned to the soil where they were taken. One set of microcosms from each treatment was harvested at t=3, 16, 25, 40, 68, and 159 d and destructively sampled. The soil was split into 0-5 and 5-15 cm depths and analyzed for total %C and %N, 13C signature, inorganic N, phospholipid fatty acids, and neutral lipid fatty acids.
Whiteley, Geoff (University of Leeds, School of
Biology, Miall Building, Leeds,
LS2 9JT, UK; Phone: +44 (0)1133432886; Fax: +44 (0)1133432835; Email: g.m.whiteley@leeds.ac.uk)
Iron Stabilization of Crop Residues as a Novell Land Management Practise for Sequestering Carbon in the Agricultural Sector
G.M. Whiteley*
Current
proposals to increase the sequestration of carbon in the agriculture sector are
necessarily directed towards financial incentives to shift the balance between
well established systems of conventional land management such as afforestation
of crop and pasture land or shifts from conventional to conservation tillage.
However, it is possible that the availability of subsidies might stimulate
innovation in the sector and encourage alternative residue management
technologies. Iron mineral impregnation of crop biomass is used in horticulture
to slow the rate of decomposition of materials such as wheat straw for
mulching. Iron bonding to cell wall polymers creates a physical and chemical
barrier to access by cellulose degrading enzymes, with the increased
recalcitrance contributing to control of composting in storage, reducing
nitrogen immobilisation and an extending the life for surface applied mulches.
Efficacy is not a simple function of recalcitrance because the addition of iron
can also induce microbial phosphorus deficiency and reduce palatability to
earthworms. Residual effects are also evident after soil incorporation as
protected straw fragments in the light fraction and as Fe-stabilized humic
material. The application of this to the treatment of crop residues in
agricultural systems has not been investigated. This paper considers the carbon
sequestration potential of a single spray treatment in year 1 consisting of 6
kg of Fe per metric ton of wheat straw applied as a ferrous sulphate solution
after harvest. The supply of materials for this spray treatment was assumed to
be $8.00 per metric ton of treated straw (assuming a delivered price of $200
per metric ton of ferrous sulphate heptahydrate). Comparisons are made between
the increased temporary storage of carbon under conventional tillage and
conservation tillage systems over a 15 year projection. For the purposes of
this study, three levels of efficacy of the iron impregnation are considered
and the annual increases in carbon stored in surface litter, light organic
matter fraction and Fe-bound humic carbon are tabulated. Finally, rental
payment values are calculated for net sequestration, using a 5% discount rate
for payments ranging from $10 to $150 per metric ton of permanent carbon
sequestration. Over the 15 year projection, the net increase in stored carbon
ranged from 0.33 metric tons per metric ton of treated crop residue in the high
scenario with conservation tillage to 0.082 metric tons per metric ton of
treated crop residue in the low scenario with conventional tillage. Increased
residue cover in the first year after treatment accounted for between 38% and
52% of the total increase in carbon retention under conservation tillage and
net storage remains correspondingly higher under conservation tillage than
conventional tillage. Rental values never exceeded $2.50 per metric ton of
treated crop residue, representing only a fraction of the cost of the
treatment. It appears unlikely that incentive payments, however priced, would
influence decisions by farmers to adopt this practice in farming systems. However,
this is not to say that the process does not have an intrinsic value in areas
such at the Pacific North West where available supplies of crop residue are
limiting factors to productivity and have an intrinsic value in erosion
protection. Large scale take up of the technology on a regional scale might
still be shown to have a measurable impact on carbon stocks in the agricultural
sector; it is just that this would be insensitive to incentive payment
inducements.
Wielopolski, Lucian (Brookhaven National Laboratory,
Environmental Sciences Department, Bldg. 490D, Upton, NY, 11973; Phone:
631-344-3656; Fax: 631- 344- 7244l; Email: wielo@bnl.gov)
Long Term Non-destructive Soil Carbon Monitoring in Tillage and No-tillage Systems
L. Wielopolski*, S. Mitra, D. Tyler, P. Denton, N. Eash, M. Essington
Increasing soil carbon content serves as a balancing act attempting to mitigate anthropogenic CO2 emissions into the atmosphere in order to slow down gradual global warming. In addition, it is well recognized that an increase in carbon soil content improves the soil quality and productivity. However, lack of non-invasive tools for soil analysis and our limited understanding of the belowground processes hinders our ability to evaluate carbon sequestration efficacy and assess soil carbon stores. One of the methods, looked upon here, of increasing soil carbon sequestration is switching from till to no-till soil management practices. Carbon has been shown to increase in many continuous no-tillage systems compared to tilled systems. Less is known about the fate of carbon when systems are changed relative to tillage. Carbon will be measured on long-term research plots (established in 1981) comparing three no-tillage soybean-cropping systems to three tilled systems. In the spring of 2002 all plots were randomly split and sampled for soil carbon and nitrogen on each side. After sampling, one side of each of the no-till and tilled plots was converted to the other tillage system. Converted plots were then sampled after the tillage conversion and all plots have been sampled each year since conversion. These data will allow the opportunity to monitor carbon changes in long-term and short- term no-tilled and tilled systems in a controlled randomized replicated experiment. We also will be sampling landscape transects across soil types and positions to evaluate terrestrial carbon spatial variation and storage. This data set, obtained by conventional destructive sampling and wet chemistry, will be compared to results obtained with a novel Soil Carbon ANalysis (SCAN) instrument that measures non-destructively soil carbon content in a continuous scan over large area. The instrument probes the soil to an approximate depth of 20 to 30 cm, depending on the soil conditions, with a footprint of about 150 cm. Such a measurement, besides being non-destructive, provides a mean carbon value for a large volume thus smoothing any possible normal lateral variability in the soil carbon content. The instrument can be used in a stationary mode, or in a mobile mode for an integrated estimate over a large area. This is in contrast to core samples that represent point measurements and for larger field sizes require a large number of cores to reduce the error to an acceptable level. The results will be rank correlated and using in-field calibration will be compared in carbon-estimated values. The predictions of the carbon content for the entire field based on stationary and scanning results will be also evaluated. Discussion of the planned experiments and the analysis will be presented.
Wightman, Jeni
(Cornell University, 905a Bradfield, Ithaca, NY, 14850; Phone: 607-255-4230;
Fax: 607-255-3207; Email: jw93@cornell.edu)
On-Farm Opportunities to Reduce Greenhouse Gas Emissions in
J. Wightman*, T. Wise, S. Vergara, A. Buttel, J. Gaunt, J. Duxbury
New
York State contributes nearly 1% of global total greenhouse gas (GHG)
emissions. The majority of greenhouse
gas emissions from New York State come from transportation (34%), heating
(27%), and electricity use (23%) (www.ccap.org/NYGHG.htm). New York State has set goals of
reducing greenhouse gas emissions below 1990 levels by 5% in 2010 and 10% in
2020. New York has also committed to
increase the proportion of electricity generated from renewable sources from
17.5% to 25% by 2013.
In an effort to identify ways for agriculture to mitigate its own greenhouse gas emissions, we examined: i) the energy use and greenhouse gas emissions for the 700,000 milking dairy herd plus young replacement stock in New York State using predominantly 1997 data, and ii) the opportunity to use biomass for fossil fuel substitution on underutilized farm lands.
While dairy is the dominant agricultural activity in New York State, our calculation of 6.5 million metric tons of CO2 equivalents from the New York dairy industry accounts for ~2.7% of the state total annual emissions. Strategies such as improving nitrogen and manure management are available to reduce emissions on farm. However, the impact of these strategies at the state level would be negligible given the low level of total emissions.
We estimate that farmers could manage their woodlots (1,649,585 ac) harvesting ¾ cord/ac/yr for timber stand improvements to be used as wood fuel thus displacing ~0.5% of the state GHG emissions. Additionally, improved management of idle, abandoned and Conservation Reserve Program land (~700,000 ac, www.nass.usda.gov) to produce grasses for energy would displace another ~1.0% of the state GHG emissions. In total the offset would be a third of the New York state 2010 goal while supplying a renewable energy resource. There is further potential from other non-farm New York lands that could be used to displace fossil fuel energy by the production of solid bio-fuels but are not included in this study.
Our conclusion is that solid biofuel production (grasses and sustainable forest management using existing infrastructure) with low input requirements and ability to utilize lands not suitable for cash crops appears to be most energetically intelligent choice for New York State farmers. Farming for fuels will displace fossil fuel emissions in other sectors and thereby make a significant contribution to the New York State goals for reducing GHG emissions.
Wilson, Gail (Konza Prairie Biological Station,
Division of Biology, Kansas State University, Manhattan, KS, 66506; Phone:
785-532-2892; Email: gwtw@ksu.edu)
Soil Quality and N Dynamics as Affected by Management Practices in Tallgrass Prairie
G.W.T. Wilson*, C. W. Rice
Long-term experimental tallgrass prairie plots, located at Konza Prairie Biological Station in the flinthills of Eastern Kansas, were subjected to 16 y of annual burning, mowing, nitrogen fertilization and untreated control sites to examine effects of these management practices on carbon sequestration and soil quality. These sites are dominated by warm-season C4 grasses (switchgrass, big bluestem, and indian grass). Annual burning and N addition each increased aboveground productivity of the dominant grasses, and burning generally increased root biomass, in soil collected from 0-5 cm depth. Biomass removal by mowing did not affect aboveground productivity but did reduce root biomass in unburned, unfertilized plots. Microbial biomass C and N were closely correlated with root productivity across these management treatments. Nitrogen fertilization increased both soil organic C and N, and increased the proportion of macroaggregates, with a concomitant decrease in microaggregates. Higher organic C and N were observed in both macro- and microaggregate fractions, as compared to unfertilized controls. Burning (annually, early spring) had no effect on soil C in the surface 5 cm, but decreased soil N and increased macroaggregate formation, as compared to corresponding unburned plots. Mowing (in late June) decreased soil C but did not influence soil aggregate formation. This study indicates that proper management of tallgrass prairie is required to maintain soil quality and utilization of certain management practices may increase a soil’s potential to sequester carbon.
Wolf, Adam (University of California-Davis, Dept of Plant Sciences, 1 Shields Ave, Davis, CA, 95616; Phone: 530-752-3450; Email: awolf@ucdavis.edu)
Spanning the Experimental Divide: Using Data at Multiple Spatial Scales to Better Constrain Gas Exchange Models
A. Wolf*, J. Six, C. Van Kessel, R. Howitt, D. Rolston, J. Hopmans, J. Mitchell
Understanding of surface greenhouse gas exchange at scales relevant to atmospheric science and climate policy remains a difficult topic: mass budgets are available only at very large or very small scales, but our typical scale of interest is somewhere intermediate. This paper describes the attempt to improve our understanding of greenhouse gas emissions at the field scale using both modeling and experimentation at multiple spatial and temporal scales. From 2003-2004, CO2 and N2O fluxes have been measured in a conventionally managed cornfield in Yolo County, CA. An eddy covariance system measured CO2 and H2O fluxes continuously over long periods over a several hectare footprint. In addition, closed chambers measured soil CO2 and N2O exchange weekly at 20-30 locations over the field. The EC measurements are rich in time, but only at one place; the CC measurements have rich spatial detail but are sparse in time. To span this spatiotemporal expanse, the biome model DNDC (“DeNitrification DeComposition”; Li, 2000) was parameterized to simulate components of greenhouse gas exchange both at the field scale and in a spatially distributed manner at the plot scale. Initial results show that the model can fairly simulate yield, but does not appear to simulate ecosystem (non-plant) respiration well, either before or during the growing season. Throughout the winter, CO2 efflux measured by eddy covariance and closed chambers show much greater respiration than was modeled. Although growing season respiration is not directly measured by eddy covariance, the chamber measurements indicate that true respiration is much greater than modeled respiration throughout the growing period. Model estimate of nitrous oxide (N2O) emission is well corroborated by the chamber measurements. Although N2O efflux is very dynamic, the measurements match up well with both the baseline flux magnitude, as well as the peaks. This is heartening, because it shows that the model can reproduce the N2O fluxes well even if its respiration estimates are biased. On balance, the model indicates that the Greenhouse Warming Potential (GWP, in CO2 units) of N2O efflux is a bit higher than for CO2: 1151 kg CO2 equivalents for CO2 versus 4886 kg CO2 equivalents for N2O. Li C.S. (2000) Modeling trace gas emissions from agricultural ecosystems. Nutrient Cycling in Agroecosystems, 58, 259-276.
Woodbury, Peter B. (Cornell
University, Crop and Soil Sciences Dept., Ithaca, NY, 4853; Phone: 607-
255-1448; Email: pbw1@cornell.edu)
P.B. Woodbury*, J.H. Cherney, J. Wightman, J.M. Duxbury, W.J. Cox, C.L. Mohler, S.D. DeGloria
New York State has set goals of
reducing greenhouse gas emissions below 1990 levels by 5% in 2010 and 10% in
2020. We evaluated how biomass fuel production could help to achieve these
goals. The suitability of lands throughout the state for increased biomass
production was analyzed for corn (Zea
mays L.), soybean (Glycine max
(L.) Merrill), switchgrass (Panicum
virgatum L.), reed canarygrass (Phalaris
arundinacea L.), unimproved grasslands, and existing mixed-species forests.
New York State has approximately 19.7 million acres of forestland (59% of
total); 6.2 million acres of crop and hay land (19%); 2.1 million acres of
pasture and old-field land (6%); 1.5 million acres of developed land (4%); 1.2
million acres of wetlands (4%), and 2.2 million acres of water (7%). Of current
pasture, old field, and hay land, we estimate that 1.5 million acres may be
currently underutilized and potentially available for herbaceous biomass crops
without reducing current row crop, corn silage, or hay silage production that
is important for New York’s dairy industry.
For corn, soybean, switchgrass, reed canarygrass and unimproved grasslands, we
predicted the suitable area and production potential for each soil type in the
state. These predictions were linked within a geographical information system
to spatially referenced soils data (STATSGO). Potential yields and areas under
good management on underutilized land were estimated to be: corn 110 bu/ac (on
1.3 million acres) , soybean 37 bu/ac (1 million acres), reed canarygrass 4.1
t/ac (1.5 million acres), switchgrass 3.5 t/ac (1.2 million acres), and
unimproved grasslands 1.9 t/ac (1.2 million acres). These crops would use the
same land base, and so are mutually exclusive strategies.
Based on inventory data from the USDA Forest Service, there are approximately
15.4 million acres of forestland that have adequate growth rates for commercial
timber production and that are not reserved for non-timber uses such as parks.
Of this timberland, 10 million acres are in mixed hardwood species and are
privately owned, not including forest industry land. We assume that half of
this land (5 million acres) is potentially available for additional biomass
production. Predicted potential additional yields based on current growth rates
of existing forests, excluding current harvests and mortality, were estimated
to average 0.5 tons/acre/year. Predicted yields using residues from timber
stand improvement cuts are estimated to be 0.8 tons/acre/year. For maximal
greenhouse gas mitigation potential, the best agricultural strategy is
producing reed canary grass for heat and the best forest strategy is timber
stand improvement cuts. Together, these strategies could reduce total New York
State emissions by 3.7%. These options provide 30-fold greater greenhouse gas
mitigation potential than corn for ethanol and 24-fold greater potential than
soybean for bio-diesel. For forests, it should be noted that greater wood
yields are possible with plantations, but we have not yet evaluated plantation
strategies. Further analysis is required to determine the degree to which these
biomass production options are feasible under economic and social constraints.
We have examined biophysical and some economic constraints to increased
production, but have not examined infrastructure constraints such as road
access, and ability of existing power plants to use biomass. Furthermore,
not all land owners are willing or able to increase biomass production, and if
they do so, not all will achieve optimal production. Therefore our estimates of
potential production could be too optimistic, but they do suggest that further
development of biomass strategies for mitigating greenhouse gas emissions is
warranted in New York State and other similar regions.
Woodbury, Peter B. (Cornell University,
Crop and Soil Sciences Dept., Ithaca, NY, 4853; Phone: (607) 255-1448; Email:
pbw1@cornell.edu)
Effects of Land Use Change on Forest Carbon Budgets Throughout the Southern USA from 1900 to 2050.
P.B. Woodbury*, L.S. Heath, J.E.
Smith
Land use change is an important
driver of terrestrial carbon cycling in the United States and quantifying the
effects of afforestation and deforestation is important for national and
international assessments. We estimated the effects of afforestation and
deforestation both historically and in future decades throughout 13 states in
the Southern U.S. This
region is important because its intensively managed forests provide more timber
products than any other entire nation. We developed matrices representing area
transitions over time between forest, agricultural, and urban land uses and
incorporated the results in a model to estimate changes in soil and forest
floor carbon stocks. Land use changes such as afforestation have long lasting
effects, so we developed historical data sets and ran the model beginning in
1900. Historical estimates of land use transitions were based on Governmental
forest and agricultural inventories. Future land use changes were based
on projections of historical data and projections from the USDA Forest Service
2003 RPA timber assessment base run. Transitions within forests, that is,
between forest types, were assumed not to alter forest floor and soil carbon
stocks. Estimates of soil carbon stocks were derived primarily from the STATSGO
database. The effects of specific land use changes on soil and forest floor
carbon fluxes were based on data from the literature.
Historically, in the
South-Central region (Texas to Kentucky), the maximum effect of land use change
occurred during the 1980s while in the Southeast region (Florida to Virginia)
it occurred during the 1940s. The total maximum effect of land use change was
also much greater in the South-Central region: 210 Tg C versus 70 Tg C in the
Southeast region. In the future, forest area is predicted to decrease in the
Southeast region by 1.4 million ha, while it is predicted to increase in the South-Central
region by 0.5 million ha. Despite this difference, the pattern of net
carbon change from 2004 until 2050 is predicted to be fairly similar in the two
regions, with sequestration of 41 Tg C (Southeast) and 57 Tg C (South-Central
region). Afforestation is predicted to sequester 119 Tg C in the Southeast
region and 117 Tg C in the South-Central region. The emission due to
deforestation is predicted to be somewhat higher in the Southeast: 78 Tg C
versus 59 Tg C in the South-Central. One key result of our model is that forest
floor carbon changes account for nearly as much carbon changes as does the
soil, even though the total mass of this pool is so much smaller. This occurs
because nearly all of the forest floor mass is assumed lost with deforestation,
while only a portion of soil carbon mass is lost.
The results of this model are
intended to improve the forest estimates of the U.S. Greenhouse Gas Inventory,
which is produced annually to meet reporting requirements under the United
Nations Framework Convention on Climate Change. From 1990 to 2004 for the
entire 13-state study area, afforestation caused sequestration of 88 Tg C, of
which 47 Tg C was in the soil and 41 Tg C was in the forest floor. During this
same period, deforestation caused emission of 49 Tg C, of which 13 Tg C was in
the soil and 36 Tg C was in the forest floor. However, the net effect of land
use change on carbon mass in soil and forest floor from 1990 to 2004 was about
6-fold smaller than the net change in carbon stocks in trees on all forestland
during this time period. Thus land use change effects for this period are
dominated by changes in tree carbon stocks.
Wright, Alan (Texas A&M University, Dept. of Soil
and Crop Sciences, College Station, TX, 77843-2474; Phone: 979-845-8738; Fax:
979-845-0456;
Email: awright@ag.tamu.edu)
Tillage, Cropping Sequence, and Fertilization Effects on 13C Abundance of Soil Physical Size Fractions
F. Dou, A.L. Wright*, F.M. Hons
Increasing soil organic C (SOC) not only plays an essential role in soil nutrient cycling, but also in mitigating the increasing concentration of atmospheric CO2. Agricultural practices that decrease soil disturbance and increase crop residue input enhance soil C sequestration. Soil physical size fractionation coupled with 13C natural abundance was utilized to study the distribution of crop residue into and the turnover of SOC fractions in continuous sorghum [Sorghum bicolor (L.) Moench.] (CS) and wheat [Triticum aestivum (L.)] (CW), continuous wheat/soybean [Glycine max (L.) Merr.] (WS), and wheat/soybean-sorghum (SWS) sequences under conventional (CT) and no tillage (NT) with and without N fertilizer in a long-term (20-year) experiment. Only surface (0-5 cm) soil samples were studied. 13C abundance of protected and unprotected resistant organic C (ROC), protected and unprotected mineral-associated C, microaggregate C, and protected (PPOC) and unprotected particulate organic C (UPPOC) were determined. Differences in 13C concentrations of crop residues significantly affected 13C concentrations of SOC in all size fractions, with greatest differences observed in more labile pools. Carbon turnover rates increased in the sequence: ROC less than silt- and clay-associated C less than microaggregate C less than POC. Tillage effects on 13C values were also observed primarily in the labile pools. Compared to CT, greater 13C values were found in POC under NT, except in UPPOC in CS and in SWS. Compared to crop sequence and tillage, effect of N addition on 13C of labile pools was minimal. Our study indicated that soil physical size fractionation, in conjunction with 13C analysis, can improve our understanding of SOC dynamics.
Wylie, Bruce (SAIC, USGS National Center, EROS, Sioux Falls, SD, 57198; Phone: 605-594-6078; Fax: 605-594-6529; Email: wylie@usgs.gov)
Rangeland
Carbon Fluxes in the
B.K. Wylie*, T.G. Gilmanov, A.B. Frank, J.A. Morgan, M.R. Haferkamp, T.P. Meyers, E.A. Fosnight, L. Zhang
Rangeland Carbon fluxes are highly variable in both space and time. In the Northern Great Plains, rainfall is an important determinant of whether this ecosystem will be a carbon sink or source. Given the large areas of rangelands and their significant soil organic matter stocks, understanding how they respond to climatic variation is important for making future predictions. Rangeland carbon fluxes associated with Net Ecosystem Exchange (NEE), gross primary productivity (Pg), total ecosystem respiration (Re) were quantified from multiple year data sets from five flux tower locations in the Northern Great Plains. Light response curve analysis was used to partition net fluxes into Pg, and Re. These flux tower measurements were then combined with 1 km2 spatial data sets of photosynthetically active radiation (PAR), Normalized Difference Vegetation Index (NDVI), temperature, precipitation, start of growing season, and soil derived data sets. Regression tree models were developed by removing infrequently variables or variables that had limited impact on model prediction. Cross validation and jackknifing approaches quantified model prediction accuracies. Maps of 10-day carbon dynamics of NEE, Pg, and Re were produced for each growing season from 1998 to 2001. Growing season carbon fluxes were combined with estimates of winter fluxes to estimate annual carbon budgets. Carbon sinks and sources were mapped and regional averages were calculated.
Yan, Xiaoyuan (Frontier Research Center for Global Change, ShaowaYokohama, 236-0001, Japan; Phone: 81-45-778-5725; Fax: 81-45-778-5496; Email: yanxy@jamstec.go.jp)
Factors Affecting Methane and Nitrous Oxide Emissions from Croplands in Asia and Potential Mitigation Options
X. Yan*, H. Akiyama, K.
Yagi
East, Southeast, and South Asia are among the most densely populated regions in the world. To meet the requirement for food, 54% of the world total chemical nitrogen fertilizer is consumed and 89% of the world rice cultivation area is located there. Thus, the emissions of methane (CH4) and nitrous oxide (N2O) from croplands in these regions have been a great concern of scientists and field measurements have been widely conducted. We have collected available field measurement results of CH4 and N2O emission from croplands in Asia and have made statistical analysis on the factors affecting the emissions. For CH4 emission from rice fields, the top influencing factors are organic amendment and water regime, both during the rice-growing season and before the rice-growing season. Soil pH and organic carbon content, and climate also affect CH4 emission. These six factors together can explain 68% of the variability in observed CH4 fluxes. In contrast to the previously reported optimum soil pH of around neutrality, an optimum soil pH of 5.0¨C5.5 for CH4 emission was found through the analysis. The average CH4 fluxes from rice fields with single and multiple drainage are 60% and 52% of that from continuously flooded rice fields. The flux from fields that were flooded in the previous season is 2.8 times that from fields previously drained for a long season and 1.9 times that from fields previously drained for a short season. Application of rice straw at 6 t ha-1 before rice transplanting can increase CH4 emission by 2.1 times; when applied in the previous season, however, it increases CH4 emission by only 0.8 times. These results indicate that CH4 emission from rice fields can be reduced by appropriate water management before and during rice season and by appropriate use of organic materials. Field measurement data of N2O emission from croplands in Asia are rather disorderly, but the fertilizer-induced N2O emission factors are generally smaller than the IPCC value of 1.25%. On average, fertilizer-induced N2O emission factor is 0.44% for upland crops and 0.30% for rice fields. Application of nitrification inhibitors may reduce 24% of the N2O emission, while the effect of slow release fertilizer is less significant. The effect of organic materials varies, depending on the degree of decomposition or the C/N ratio of the materials. Direct application of straw tends to reduce N2O emission. Decomposed organic materials increase N2O emission, but not as effective as inorganic fertilizer at equal nitrogen basis.
Yoo, Gayoung (University of Illinois, Dept of Natural Resources, Urbana, IL, 61801; Phone: 217-333-4912; Email: gayoo@uiuc.edu)
G. Yoo*, M.M. Wander
Use of No-tillage (NT) practices fails to reliably increase soil C sequestration in fine-textured soils. Here we report on a study conducted to explain differences in C dynamics at two sites in Illinois where long-term use of NT practices has increased SOC storage at one site, Monmouth, but not at the other, DeKalb. Efforts emphasized SOC mineralization because there was no difference in average crop yield from 1989-2002 in NT or conventional tillage (CT) plots and soil erosion was assumed to be negligible because fields were quite level. Soil CO2 evolution rates were measured in 2000, 2001, and 2002 along with soil temperature, gravimetric water content, bulk density, penetration resistance, and pore size distribution. In DeKalb (silty clay loam soil), there was no difference in the mean (μmol m-1 s-1) or specific (μgCO2 s-1 / μg SOC) C mineralization rates of NT and CT soils. In Monmouth (silt loam soil), both mean and specific SOC mineralization rates were greater from soils under CT than NT management. Differences in SOC mineralization rates were consistent with previously observed differences in SOC sequestration. Correlation among physical parameters and nonlinear regression of mean CO2 evolution rates with soil temperature and water content indicated that soil water content interacted with soil structure to influence SOC mineralization. Pore size distribution helped explain differences in soil water-structure interactions at these two sites. Macroporosity (>30 μm) was relatively reduced in the NT soils at Monmouth but not in DeKalb; this suggests soil compaction limits SOC mineralization in NT soils at Monmouth. The least limiting water range (LLWR), an index that integrates clay content, bulk density and soil moisture, predicted observed mean soil CO2 evolution patterns better than any individual physical parameter. The LLWR in DeKalb was lower than in Monmouth and did not differ as a result of tillage practices and indicated in DeKalb, high clay content limits soil water availability for SOC mineralization regardless of tillage practices. Whereas in Monmouth, the significantly lower LLWR in the NT soil indicated that SOC mineralization was limited by higher soil strength. By increasing our understanding of structural controls over SOC mineralization, we should be able to better predict whether or not the adoption of NT practice will increase SOC sequestration at individual sites. Structural parameters, and not just soil texture, should be included in simulation models to accurately predict SOC dynamics.
[1] The CarboInvent project unifies scientific efforts of 14 Partners located in 10 countries (Austria, Belgium, Czech Republic, Finland, Germany, Hungary, Italy, Ireland, Spain, Sweden) and European Community. The project activity was initiated on 1 Nov. 2002 and the financing period ends on 31 Oct. 2005.