Submitted to: Sustainable Development and Global Climate Change: Conflicts and Connection
Publication Type: Abstract Only
Publication Acceptance Date: December 5, 1995
Publication Date: N/A
Technical Abstract: There is a need for a better understanding of the tillage processes and mechanisms leading to carbon loss and how this is linked to soil productivity, soil quality and carbon sequestration. The objective of this work was to quantify the carbon dioxide loss following several methods of tillage. Carbon dioxide and water vapor fluxes were measured immediately after tillage using a large portable closed chamber designed for measuring crop canopy gas exchange. Tillage methods included moldboard plow, moldboard plow plus disk harrow, chisel plow, disk harrow and various conservation tillage tools compared with a treatment not tilled. Moldboard plow was the most disruptive tillage treatment with most residue incorporation, greatest surface roughness, largest soil surface area and air spaces that all promoted carbon dioxide loss, compared to the plots not tilled. The short-term carbon dioxide losses 5 hours after four conservation tillage tools was only 31% of that of the moldboard plow. Moldboard plowing appears to have two major effects, one to loosen and invert the soil to allow rapid CO2 loss and O2 entry, and secondly, to incorporate and mix residues for enhanced microbial attack. The smaller CO2 loss following conservation tillage tools is significant and suggests progress in developing conservation tillage tools and policy implications that can enhance soil carbon management. Conservation tillage reduces the extent, frequency and magnitude of mechanical disturbance caused by the moldboard plow and reduces the air-filled macro pores and slows the rate of carbon oxidation. Any effort to decrease tillage intensity and maximize residue return should result in carbon sequestration for enhanced environmental quality.