INTENSIVE TILLAGE AS A MECHANISM FOR CO2 EMISSION FROM SOIL

Authors: Reicosky, Donald

Submitted to: International Workshop on Conservation Agriculture for Sustainable Wheat Production in Rotation with Cotton in Limited Water Resources Areas
Publication Type: Proceedings
Publication Acceptance Date: 10/18/2002
Publication Date: 10/18/2002
Citation: REICOSKY, D.C. INTENSIVE TILLAGE AS A MECHANISM FOR CO2 EMISSION FROM SOIL. PROCEEDINGS OF INTERNATIONAL WORKSHOP ON CONSERVATION AGRICULTURE FOR SUSTAINABLE WHEAT PRODUCTION IN ROTATION WITH COTTON IN LIMITED WATER RESOURCES AREAS. TASHKENT, UZBEKISTAN. 2002. 5 P.

Interpretive Summary:

Technical Abstract: The influence of agricultural production systems on greenhouse gas generation and emission may affect potential global climate change. Agricultural ecosystems can play a significant role in production and consumption of greenhouse gases, specifically, carbon dioxide (CO2). Information is needed on the mechanism and magnitude of gas generation and emission from agricultural soils with specific emphasis on tillage mechanisms. This research evaluated the impact of different tillage methods on the short-term CO2 and water vapor flux from a clay loam soils. In the first study, four tillage methods were moldboard plow only, moldboard plow plus disk harrow twice, disk harrow and chisel plow using standard tillage equipment following a wheat (T. Aestivum L) crop compared with no tillage. The CO2 flux was measured with a large portable chamber commonly used to measure crop canopy gas exchange initiated within five minutes after tillage and continued intermittently for 19 days. The moldboard plow treatment buried nearly all of the residue and left the soil in a rough, loose, open condition and resulted in maximum CO2 loss. The carbon (C) released as CO2 during the 19 days following the moldboard plow, moldboard plow plus disk harrow, disk harrow, chisel plow and not tilled treatments would account for 134%, 70%, 58%, 54% and 27% respectively of the C in the current years crop residue. The short-term CO2 losses five hours after four conservation tillage tools was only 31% of that of the moldboard plow. The moldboard plow lost 13.8 times as much CO2 as the soil area not tilled while different conservation tillage tools lost only 4.3 times. Tillage-induced CO2 loss after strip tillage tools, spaced at 76 cm, was measured with a large portable chamber. No-till had the lowest CO2 flux during the study and moldboard plow had the highest immediately after tillage. Other forms of strip tillage had an initial flush between these extremes, with both the 5- and 24-hour cumulative losses related to soil volume disturbed by the tillage tools. Reducing the volume of soil disturbed by tillage and direct seeding should enhance soil and air quality by increasing soil C content. The smaller CO2 loss following conservation tillage tools is significant because it suggests that progress in developing conservation tillage tools that enhance soil C management is being made. Conservation tillage reduces the extent, frequency and magnitude of mechanical disturbance caused by the moldboard plow and reduces the air-filled macropores and slows the rate of C oxidation. Any effort to decrease tillage intensity and maximize residue return should result in C sequestration for enhanced environmental quality.