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Title: Predicting soil organic carbon sequestration in crop production systems of the southeastern USA with EPIC and the soil conditioning index

Author
item Abrahamson Beese, Deborah
item CAUSARANO, H - USDA-ARS
item WILLIAMS, J - TEXAS A&M UNIVERSITY
item NORFLEET, M - USDA-NRCS
item Franzluebbers, Alan

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2008
Publication Date: 3/30/2009
Citation: Abrahamson Beese, D.A., Causarano, H.J., Williams, J.R., Norfleet, M.L., Franzluebbers, A.J. 2009. Predicting soil organic carbon sequestration in crop production systems of the southeastern USA with EPIC and the soil conditioning index. Journal of Soil and Water Conservation Society. 64:134-144.

Interpretive Summary: Agricultural management systems are being evaluated to improve soil quality and sequester soil organic carbon with modified decision support systems. A collaboration of scientists from the USDA-Agricultural Research Service in Watkinsville Georgia and Beltsville Maryland, USDA-Natural Resources Conservation Service, and Texas A&M University tested the performance of a recently modified decision support system (EPIC v. 3060) against a simpler decision support tool currently used by the USDA-Natural Resources Conservation Service to identify soil management systems that contribute to improved soil quality. Management systems common to the southeastern USA such as corn/cotton/cover crop rotation systems with and without tillage were evaluated at three locations (Blackland Prairie in Texas, Coastal Plain in Alabama, and Mississippi Valley Uplands). All but one of the systems was predicted to have higher soil carbon after fifty years with the largest increases in the clay soil of the Blackland Prairie and with added dairy manure fertilizer in the sandy soil of the Coastal Plain under no tillage. Soil carbon decreased in the silt loam soil in Mississippi with conventional tillage (traditional management). No-tillage management of cotton with a wheat cover crop and other crop rotations with high-residue producing crops increased soil carbon. This will be of great importance to land managers and policy makers for improving soil quality and reducing carbon emissions from agricultural operations in the southeastern USA although there is still a great need for field-based measurements of soil quality in conservation management systems to fully validate these tools.

Technical Abstract: The Soil Conditioning Index (SCI), administered by the USDA-Natural Resource Conservation Service, predicts a positive or negative trend in soil organic carbon (SOC) based on knowledge of field operations, erosion loss, and organic matter inputs, but has not been adequately calibrated against long-term management conditions that could affect SOC dynamics. We calibrated the Environmental Policy Integrated Climate model (EPIC v. 3060) for three major land resource areas in the southeastern USA using 5- to 10-yr measured SOC data to develop a predictive relationship of SOC (50-yr simulations) with SCI values. Management systems included conventional tillage (CT) and no tillage (NT) in (1) a 2-yr rotation of wheat (Triticum aestivum L.)/sorghum (Sorghum bicolor (L.) Moench)-corn (Zea mays L.) with low and high fertilizer application on a Blackland Prairie site in Texas, (2) a 2-yr rotation of corn-cotton (Gossypium hirsutum L.) with and without dairy manure application on a Coastal Plain site in Alabama, and (3) in monoculture cotton on a Mississippi Upland site. Simulated SOC sequestration using EPIC during 50 yr was 7.9 +/- 5.7 Mg/ha among 10 management conditions. Across sites and fertilizer conditions, SOC sequestration was greater under NT (9.5 Mg/ha) than under CT (6.3 Mg/ha) (P < 0.01). Although simulated SOC using EPIC was positively related with SCI values, the relationship was stronger when combined with other simulated data from the southeastern USA. This study shows that EPIC and the SCI could be useful tools to determine SOC storage among different management systems in the southeastern USA.