Franzluebbers, Alan (USDA-ARS, Watkinsville, GA, 30677; Phone: 706-769-5631; Fax: 706-769-8962; Email: afranz@uga.edu)

Soil Organic Carbon Sequestration in Cotton Production Systems of the Southeastern USA

A.J. Franzluebbers *, H.J. Causarano, D.W. Reeves, J.N. Shaw, M.L. Norfleet

Conservation-oriented agricultural management systems have been suggested to sequester soil organic C (SOC), improve soil quality, and increase crop productivity. Our objective was to summarize and synthesize available literature related to SOC sequestration in cotton production systems of the southeastern USA. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.55 Mg C/ha/yr. Variation was large, but was expected based on the diversity of soils, cropping systems, and experimental conditions that occurred among locations. By implementing no tillage continuously for 10 years on a typical soil in the southeastern USA, SOC to a depth of 20 cm could be expected to increase from 25 Mg C/ha initially to 30 Mg C/ha (19% increase). More diverse rotations of cotton with high-residue-producing crops such as corn and small grains would sequester greater quantities of SOC than continuous cotton. Available data suggested that no-tillage cropping with a cover crop sequestered 0.67 +/- 0.63 Mg C/ha/yr, while that of no-tillage cropping without a cover crop sequestered 0.34 +/- 0.47 Mg C/ha/yr. Conservation tillage with cover cropping is an appropriate technology for SOC sequestration and complements additional benefits of reducing soil erosion, reducing fuel cost, increasing biological diversity, and improving nutrient cycling.