Submitted to: Encyclopedia of Soil Science
Publication Type: Book / Chapter
Publication Acceptance Date: 9/15/2005
Publication Date: 3/27/2006
Citation: Reicosky, D.C. 2006. Tillage and gas exchange. In: Lal, R., editor. Encyclopedia of Soil Science. 2nd edition. New York, NY: Marcel Dekker. p. 1773-1775.
Technical Abstract: In traditional agricultural production, tillage of the soil has been an integral part of the production process. Tillage is the mechanical manipulation of soil and crop residue to prepare a seedbed where crop seeds are planted, sprout, take root and grow into plants to produce grain. Intensive tillage loosens soil, buries crop residue, enables the soil to warm and dry, and improves the flow of water and air within the soil. This work reviews the mechanism and magnitude of greenhouse gas generation (CO2) and emission from agricultural soils with specific emphasis on tillage mechanisms. The tillage-enhanced gas exchange affects the processes that impact the accumulation and loss of soil carbon (C) in agricultural systems. Tillage increases water infiltration and increases the soil porosity, especially large pores, which allow greater movement of soil gases through the soil. Diffusion allows movement of gases into or out of the soil from higher to lower concentrations. Moldboard plowing loosens and inverts soil and allows rapid CO2 loss and oxygen entry. It also incorporates and mixes residues to enhance microbial decomposition and respiration (oxidation). Stirring the soil in tillage is analogous to stirring the coals in a fire. The smaller CO2 loss following conservation tillage tools is significant and suggests progress in developing conservation tillage tools that can enhance soil C management. Any effort to decrease tillage intensity and maximize residue return to the surface will reduce gaseous losses and should result in C sequestration for enhanced environmental quality.