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Title: Soil Organic Carbon Sequestration Simulated by EPIC in Cotton Rotations from Three Major Land Resource Areas in the Southeastern USA

Author
item Abrahamson Beese, Deborah
item NORFLEET, M - Natural Resources Conservation Service (NRCS, USDA)
item CAUSARANO, HECTOR - Auburn University
item WILLIAMS, JIMMY - Texas A&M University
item SHAW, JOEY - Auburn University
item REEVES, D - Former ARS Employee
item Franzluebbers, Alan

Submitted to: Southern Conservation Agricultural Systems Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2006
Publication Date: 6/26/2006
Citation: Abrahamson Beese, D.A., Norfleet, M.L., Causarano, H., Williams, J.R., Shaw, J.N., Reeves, D.W., Franzluebbers, A.J. 2006. Soil Organic Carbon Sequestration Simulated by EPIC in Cotton Rotations from Three Major Land Resource Areas in the Southeastern USA. pp.217-218. In Proc. 28th Southern Conservation Sytems Conf. (CD-ROM), 26-28 June 2006, Amarillo, TX. 2006.

Interpretive Summary: Soils in the southeastern USA have inherently low organic matter content, primarily due to excessive tillage combined with the favorable climatic conditions for decomposition. Scientists from the USDA Agricultural Research Service in Watkinsville Georgia collaborated with scientists from Auburn University, Texas A&M University, and USDA Natural Resources Conservation Service to test soil carbon changes in cotton rotations using the EPIC v. 3060 model and the soil conditioning index (SCI). Both models predicted soil organic carbon sequestration under no-tillage cotton management, but loss of soil organic carbon under traditional, conventional tillage systems. These results will have importance to landowners and managers in the southeastern USA to predict changes in soil organic matter with different tillage and crop management techniques.

Technical Abstract: Sequestration of soil organic carbon (SOC) in the southeastern USA is perceived as occurring at a relatively low rate, because of the inherent low SOC content of most agricultural soils. However, recent field estimates of SOC sequestration in conservation management systems suggest that the sequestration rate could be higher than in other regions of the country. We used the EPIC v. 3060 model and the soil conditioning index (SCI) to estimate long-term SOC storage at Temple TX, McColl SC, and Watkinsville GA using four management systems: (a) cotton with conventional tillage, (b) cotton with no tillage, (c) corn-cotton rotation with no tillage, and (d) bermudagrass-corn-cotton rotation with no tillage. All no-tillage systems used wheat as a cover crop. Simulated SOC sequestration averaged 0.46 Mg/ha/yr under the three no-tillage management systems and -0.03 Mg/ha/yr under conventional tillage with EPIC. The SCI also predicted a strong difference in SOC sequestration between conventional and no tillage. Differences in SOC sequestration among crop rotations were not readily apparent with EPIC, but were with SCI. Predictions of SOC sequestration with EPIC were related to the SCI, but not necessarily in a linear manner as previously suggested. Cotton lint yield with no tillage averaged 88% of yield with conventional tillage, but lint water-use efficiency was not different between tillage systems. Under the simulated management and environmental conditions selected, the SCI appears to be a valuable method for making reasonable, cost-effective estimates of potential SOC sequestration in the southeastern USA, although validations under actual field conditions are still needed.