Author
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Reicosky, Donald |
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Submitted to: Carbon Sequestration In Soil An International Symposium
Publication Type: Proceedings Publication Acceptance Date: 7/24/1996 Publication Date: N/A Citation: N/A Interpretive Summary: The increase in the carbon dioxide in the atmosphere has attracted interest because of concerns about the potential global warming and the prospects of using soil as a place to stash carbon dioxide released by human activity. The cumulative effect of intensive tillage and many cropping rotations has been an undesirable change in soil physical, chemical and biological properties, primarily due to the decrease in soil carbon. Recent studies involving tillage methods indicate major gaseous loss of carbon immediately after tillage related to tillage intensity. This work compared fall and spring tillage methods. There was generally more carbon dioxide released in the fall than there was in the spring even though the soil was at nearly the same temperature and water content. The results suggest differences in the activity of the soil organisms in the fall and the spring that may have contributed to the lower amount of soil carbon dioxide loss in the spring. These results are significant to farmers and policy makers because tillage can result in substantial losses of carbon dioxide to the atmosphere. This information will assist scientists and engineers to develop improved methods of tillage to maximize carbon retention in the soils and minimize carbon loss. The information will be beneficial to farmers because they can develop and utilize new management techniques that can enhance soil carbon management by increasing the quantity and quality of the carbon and residues and by changing the type and intensity of tillage. We all will benefit as farmers maintain crop production with minimal impacts on the environment. Technical Abstract: Soil organic matter is the foundation of sustainable agriculture and is highly dependent on management decisions that influence the intensity of tillage and the amount and placement of residues. Large soil carbon reservoirs are of interest because soil can serve as a major source or sink for carbon dioxide, depending on the level of management. The objective of fthis work was to quantify the carbon dioxide loss following several method of tillage, both in the fall of 1992 and the spring of 1993 on a Barnes loam in West Central Minnesota. 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 and disk harrow only compared with a treatment not tilled. Moldboard plow was the most disruptive tillage treatment with most residue incorporation, greatest tsurface roughness, largest soil surface area and air spaces that all promoted carbon dioxide loss, compared to the plots not tilled. The relative flux differences based on tillage methods were similar in both spring and fall, only smaller magnitude in the spring. The seasonal difference was apparently due to cooler soil temperatures and wetter soil conditions that determined the flux and suggests fall tillage resulted in more carbon dioxide loss than spring tillage. Large differences in CO2 loss between conventional tillage and no-tillage and the smaller difference between spring tillage and fall tillage reflect the need for improved conservation tillage and residue management systems to enhance soil quality and promote carbon sequestration. |
