Novak, Jeff (USDA-ARS-CPRC, Florence, SC USDA-ARS-CPRC, 2611, West Lucas Street, Florence, SC, 29501; Phone: 843-669-5203; Fax: 843-669-6970;� Email: novak@florence.ars.usda.gov)

Utilization of Conservation Tillage Practices to Rebuild Organic Carbon Levels in a Sandy, Coastal Plain Soil

J. M. Novak *, P. J. Bauer, P. G. Hunt

The pedogenic process in well-drained sandy, Coastal Plain soils has resulted in relatively low soil organic carbon (SOC) levels.� In these soils, the predominance of sand-size particles, rapid internal drainage, and high residue oxidation rates causes rapid residue losses and a low build-up of SOC.� Cultivation of soils using conventional tillage practices, whereby the residue is mixed into the soils, has increased the decline in SOC levels.� Recent research, however, indicates that conservation tillage practices, which minimize residue incorporation, can increase SOC levels, but the increase is limited to the top few cm of soil.� Long-term conservation and conventional tillage plots have been managed for 24 years in a sandy, well-drained Coastal Plain soil (Norfolk loamy sand).� Crop rotation management in these plots consisted of corn, soybeans, winter wheat, and cotton.� After 24 years of tillage management, annual deep coring (0 to 90-cm) within these plots has revealed that the surface SOC levels (0 to 5-cm depth) in soils under conservation tillage were significantly higher (1.33 % SOC, P less than 0.001) compared to soil under conventional tillage (0.84%).�� Mean SOC levels in lower profile depths were not significantly different (P greater than 0.05) between tillage systems.� Efforts currently in progress are to enhance SOC sequestration in lower soil profile depths (below 5-cm) with a cover crop that has a high below ground root biomass (Secale cereale).