SOIL CARBON AND CLIMATE CHANGE NEWS

 

From Kansas State University's:

Consortium for Agricultural Soils Mitigation of Greenhouse Gases (CASMGS)

http://soilcarboncenter.k-state.edu

 

Charles W. Rice, K-State Department of Agronomy, National CASMGS Director

(785) 532-7217 cwrice@ksu.edu

Scott Staggenborg, K-State Department of Agronomy (785) 532-7214 sstaggen@ksu.edu

Steve Watson, CASMGS Communications (785) 532-7105 swatson@ksu.edu

 

 

April 24, 2009

No. 66

 

Research:

* Effect of single tillage operation on carbon sequestration in a no-till system

 

National:

* EPA changes position on carbon dioxide

* National Association of Wheat Growers endorses Waxman-Markey House bill on greenhouse gases

* EPA reports that US greenhouse emissions rose in 2007

* More qualified greenhouse gas experts needed in the U.S.

 

 

 

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Effect of single tillage operation

on carbon sequestration in a no-till system

 

No-till crop production systems have been found to increase soil carbon sequestration in most situations. But sometimes circumstances arise in which a one-time tillage operation becomes necessary in an otherwise continuous no-till system. What effect will such a single low-intensity tillage operation have on stored soil carbon? Would a single low-intensity tillage operation reverse years of carbon accumulation in no-till?

 

To answer this question, Chuck Rice, professor of agronomy at Kansas State University, and K-State graduate student Chad Asmus, conducted research at three locations in western Kansas. The crop rotation at two of the sites was wheat/corn/fallow. At the other site, the field was in continuous wheat. All sites were dryland. The three locations had all been under continuous no-till cropping for at least five years. Three types of low-intensity tillage operations were then performed at each site:

 

* Disk plow

* Chisel plow

* Sweep plow

 

One plot was kept in no-till production. In the tillage plots, the land was returned to no-till after the one-time tillage operation was performed. The soil was sampled at three depths (0-5 cm, 5-15 cm, and 15-30 cm) for total carbon, aggregate distribution, and bulk density pre-tillage, then at 9 and 12 months after the tillage treatment.

 

Key Findings

 

* A single tillage pass with a disk, sweep, or chisel did not affect soil organic carbon (SOC) stocks compared to uninterrupted no-till under dryland cropping in a semi-arid environment. At the Wallace County site, there was a slight increase in SOC concentration when averaged over the 0-30 cm depth with the disk plow treatment, but no significant increase in soil C mass (which takes bulk density into account) to a depth of 30 cm. The increase in soil C concentration after tillage at this one location can be attributed to the shallow incorporation and decomposition of surface residue. Although most of the residue-C and some of the SOC is respired as CO₂ following tillage, there can be a net increase in soil C concentration if a sufficient amount of surface residue is introduced into the soil. 

 

Whole soil C mass by tillage and depth, 12 months after treatment

 

Wallace Co., Kansas (Wheat/corn/fallow)

 

Spearville, Kansas (Continuous wheat)

 

Tribune, Kansas (Wheat/corn/fallow)

 

 

 

* Aggregation was not significantly affected by a single tillage operation. There were some changes in aggregation due to cropping sequence and changes in soil moisture, but not due to the single tillage operation. At all three sites there was a general trend for the amount of large microaggregates to decrease and small microaggregates to increase over time. 

 

* The greatest mass of aggregate-associated C existed in the large microaggregate fraction for all three soils. It is this aggregate size fraction that had the greatest influence on whole soil C for these locations. However, other pools of organic C contributed to the net accumulation or loss of whole soil organic C besides aggregate-protected C. 

 

* Tillage did not significantly affect bulk density at any location.

 

Other Similar Studies

 

The results of this study are similar to those of several studies involving more intensive one-time tillage operations, such as:

 

1. Michigan. In this study, plowing a no-till field one time had no effect on SOC mass at the 0-30 cm depth 5 years later. Kettler, T.A., D.J. Lyon, J.W. Doran, W.L. Powers, and W.W. Stroup.  2000. Soil quality assessment after weed-control tillage in a no-till wheat-fallow cropping system.  Soil Sci. Soc. Am. J. 64: 339-346.

 

1. Michigan. In this study, one-time plowing of a long-term no-till plot did not affect SOC mass in the top 20 cm of soil, although it did redistribute the C so that less was in the upper surface layer. Pierce, F.J., M.-C. Fortin, and M.J. Staton. 1994. Periodic plowing effects on soil properties in a no-till farming system. Soil Sci. Soc. Am. J. 58: 1782-1787.

 

2. Nebraska. This study of rainfed systems in western Nebraska had findings similar to the Michigan study above. A one time tillage operation redistributed C within the top 30 cm of soil, but did not affect the total amount of SOC in the soil. Quincke, J.A., C.S. Wortmann, M. Mamo, T. Franti, and R.A. Drijber. 2007. Occasional Tillage of No-Till Systems: Carbon Dioxide Flux and Changes in Total and Labile Soil Organic Carbon. Agron. J. 99(4): 1158 - 1168.

 

3. Nebraska. In this study, plowing a no-till field one time had no effect on SOC levels at the 0-30 cm depth 5 years later. Kettler, T.A., D.J. Lyon, J.W. Doran, W.L. Powers, and W.W. Stroup.  2000. Soil quality assessment after weed-control tillage in a no-till wheat-fallow cropping system.  Soil Sci. Soc. Am. J. 64: 339-346.

 

4. Ontario, Canada. Plowing a no-till field one time had no effect on SOC mass on most soils 18 months later, except for a sandy loam soil with low initial organic matter levels. VandenBygaart, A.J. and B.D. Kay. 2004. Persistence of soil organic carbon after plowing a long-term no-till field in southern Ontario, Canada. Soil Sci. Soc. Am. J. 68(4):1394-1402.

 

Some other studies on this topic have had slightly different findings for soil the effects of a one-time tillage on soil aggregation, however. In a Michigan study, plowing a no-till field one time immediately and substantially reduced soil aggregation, and that this condition persisted for several years. Soil carbon mass remained unchanged averaged over the 0-20 cm depth. Grandy, A.S. and G. P. Robertson. 2006. Aggregation and organic matter protection following tillage of a previously uncultivated soil. Soil Sci. Soc. Am. J. 70(4): 1398 - 1406.

 

Summary

 

In the arid environment of western Kansas, the K-State team found that a single tillage event did not have a deleterious effect on sequestered carbon or aggregation as long as the land is immediately returned to no-till.

 

 

-- Steve Watson, CASMGS Communications

swatson@ksu.edu

 

 

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Environmental Protection Agency Changes

Position on Carbon Dioxide

 

The U.S. Environmental Protection Agency has concluded that carbon dioxide and five other greenhouse gases are a danger to public health and welfare.

It is the first step to regulating pollution linked to climate change. The next step is a 60-day comment period before issuing a final ruling. If the regulation goes into effect, it is likely to result in limitations on carbon dioxide emissions from vehicle tailpipes, power plants, and industrial sources, among others.

The action was prompted by a Supreme Court ruling two years ago that said greenhouse gases are pollutants under the Clean Air Act and must be regulated if found to be a human health danger.

There are now two possible pathways that could lead to limits being imposed in the U.S. on greenhouse gas emissions. One path is by EPA regulations under the Clean Air Act. The other is by legislative action by the Congress. Congress is considering imposing an economy-wide cap on greenhouse gas emissions along with giving industry the ability to trade emission allowances to mitigate costs.

 

-- Steve Watson, CASMGS Communications

swatson@ksu.edu

 

 

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Waxman-Markey House Bill on Greenhouse Gases

endorsed by many

 

In early April, U.S. House Energy and Commerce Committee leaders released a discussion draft of climate change legislation expected to move toward completion before August. The Waxman-Markey discussion draft calls for an economy-wide, greenhouse gas cap-and-trade system. It is sponsored by Henry Waxman (D-Calif.) and Ed Markey (D-Mass.). The legislation is called the American Clean Energy and Security Act of 2009. It would essentially launch a federal carbon market.

 

This proposed bill has received the backing of top cabinet officials in the Obama administration and the U.S. EPA. In addition, a coalition of 12 agricultural groups, including the National Association of Wheat Growers (NAWG), endorses the bill. NAWG has stated that the Waxman-Markey bill “is a constructive first step on the road to climate change legislation.” Waxman has said the Energy and Commerce Committee will complete the bill before Memorial Day Recess. House Speaker Nancy Pelosi (D-Calif.) has said the full House will complete it before recessing in August.

 

One impetus for Congressional action on this issue is imminent regulation of carbon dioxide by the Environmental Protection Agency (EPA). The Supreme Court ruled in 2007 that carbon dioxide can be regulated by the EPA if the Agency determines it is a public health threat, which EPA leaders are poised to do.

 

Many in the agricultural community prefer Congressional action to EPA regulations, which would cover any activity emitting more than 100 tons of carbon per year.

 

For more on the discussion draft of the Waxman-Markey bill, including a summary and the full text, see:
http://bit.ly/1REc

 

Another summary table of the proposed bill, from the Pew Center on Climate Change, can be found at:

http://www.pewclimate.org/docUploads/SummaryTable-Discussion%20Draft-3.31.09.pdf

 

For more on NAWG’s work in this area and a copy of the agricultural principles, see: www.wheatworld.org/climatechange

 

 

-- Steve Watson, CASMGS Communications

swatson@ksu.edu

 

 

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EPA reports that US greenhouse emissions

rose in 2007

 

U.S. greenhouse gas emissions rose 1.4 percent in 2007 compared to the previous year, the U.S. Environmental Protection Agency reported recently. The report also indicates that U.S. emissions of climate-warming gases such as carbon dioxide and methane rose 17.2 percent from 1990 to 2007.

 

The increase in 2007 was mainly due to a rise in carbon dioxide emissions related to fuel and energy consumption, the EPA stated. There was more demand for heating fuel and electricity due to cooler winter and warmer summer temperatures, compared to 2006.

 

There was also increased demand for fossil fuels to generate electricity, coupled with a significant decrease -- 14.2 percent -- in hydropower generation to meet this demand. Total emissions of the six main greenhouse gases in 2007 were equivalent to 7,150 million metric tons of carbon dioxide. These gases include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

 

The EPA's report is the latest annual greenhouse gas inventory submitted to the United Nations Framework Convention on Climate Change, which sets an overall framework for intergovernmental efforts regarding climate change.

 

For more details, see: http://epa.gov/climatechange/emissions/usinventoryreport.html

 

-- Reuters News Service, April 15, 2009

 

 

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More qualified greenhouse gas

Experts needed in the U.S.

 

A guest commentary by Tom Baumann, GHG Management Institute, and Frank D. De Safey, Sequence Staffing, in the Feb. 13, 2009 issue of “Carbon Market North America” from PointCarbon contends that there is a shortage of qualified greenhouse gas experts in the U.S.

 

Baumannn and De Safey state: “With the new US administration preparing to make substantial greenhouse gas (GHG) commitments … there is greater realization of the importance and growing demand for more and more qualified experts. How are we going to accurately measure and account for these reductions? How are we going to ensure that the system is fair and transparent, especially when we use market mechanisms, which are subject to potential abuse if not checked and regulated in some way? In short, we will need a class of GHG professionals.”

 

The authors call on universities to start training more experts in this field to meet the expected demand.

 

To read the full commentary, see: http://www.pointcarbon.com/polopoly_fs/1.1056634!CMNA20090213.pdf

 

 

-- Steve Watson, CASMGS Communications

swatson@ksu.edu

 

 

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MEETINGS OF INTEREST

May 4-7, 2009
8th Annual Conference on Carbon Capture and Sequestration
Pittsburgh, PA
http://carbonsq.com/index.htm

May 12-15
2nd Climate Change Technology Conference
Ontario, Canada
http://cctc2009.ca/en/index.html

 

 

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swatson@ksu.edu