Submitted to: Soil and Water Conservation Society
Publication Type: Monograph
Publication Acceptance Date: 6/15/1995
Publication Date: N/A
Interpretive Summary: The increase in the carbon dioxide in the atmosphere has attracted interest due to the concerns about potential global warming and the prospects of using soil as a sink for carbon released by human activity. Recent studies involving tillage methods indicate major gaseous loss of carbon immediately after tillage. Differences in the CO2 losses as a result of tillage methods were related to soil fracturing that facilitated movement of carbon dioxide out of and oxygen into the soil. The moldboard plow left nearly all of the soil in a rough, loose and open condition, that resulted in the maximum CO2 loss. Conservation tillage tools that leave more residue on the surface had only 31% of the CO2 loss caused by the moldboard plow. These results are significant to farmers and policy makers in that tillage results in substantial short-term gaseous losses of CO2. Information will be beneficial to farmers because they can develop and utilize new management techniques for enhancing soil carbon by increasing the quantity and quality of carbon residues and by changing the type and intensity of tillage. This information will assist scientists and engineers to develop improved methods of tillage to minimize the gaseous loss and improved soil carbon management. The information will also directly benefit the farmers as they try to maintain crop production with minimal impact on the environment. Agriculture's contribution to controlling the increased carbon dioxide in the atmosphere to minimize potential global warming requires that we manage soil carbon for sequestration and utilize soil as a sink for carbon released by other human activity.
Technical Abstract: Production of food and fiber depends on natural soil fertility and proper soil management. One of the keys to soil fertility is soil organic matter. This work assesses research with tillage systems in an attempt to compare their impacts from the economic, environmental and soil quality points of view and to present a credible summary of the current state of knowledge of agricultural tillage. Historical data reviewed showed intensive tillage of agricultural soils has led to substantial losses of soil carbon that ranged from 30-50%. Virtually all of the research results lead to the conclusion that intensive tillage, primarily moldboard plowing, has decreased soil carbon in virtually all crop production systems. Differences in soil carbon decreases were related to various crop rotations and residue returned. Recent studies involving tillage methods indicate major gaseous loss of carbon immediately after tillage. Differences in CO2 loss were related to soil fracturing that facilitated the movement of CO2 out of and oxygen into the soil. Gaseous losses of CO2 after using new conservation tillage tools were only 31% of the moldboard plow. While primarily designed to leave crop residue on the surface, these conservation tillage tools can have a beneficial effect that results in less carbon dioxide loss and enhanced soil carbon management. Increased adoption of new and improved forms of conservation tillage that include no-till offer significant potential to preserve or to increase soil carbon levels.