Klik, Andreas (BOKU-Univ. of Nat. Res and Appl. Life Sci., Vienna, A-1190, Austria, Phone: 00431-360065472; Fax: 00431-360065499; Email: andreas.klik@boku.ac.at)

Carbon Dioxide Emissions From Soils With and Without Erosion Control

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