Submitted to: USDA Symposium on Natural Resource Management to Offset Greenhouse Gas Emissions
Publication Type: Abstract only
Publication Acceptance Date: 10/8/2002
Publication Date: 10/8/2002
Citation: NOVAK, J.M., FREDERICK, J.R., BAUER, P.J., BUSSCHER, W.J., HAYES, J. ORGANIC CARBON DISTRIBUTION IN COASTAL PLAIN SOILS UNDER CONTRASTING MANAGEMENT REGIMES.. USDA SYMPOSIUM ON NATURAL RESOURCE MANAGEMENT TO OFFSET GREENHOUSE GAS EMISSIONS. 2002. Interpretive Summary:
Technical Abstract: Increasing soil organic carbon (SOC) by way of crop management in the southeastern Coastal Plain region is a daunting task. In this region, many sandy upland soils have low SOC contents because of a warm and moist climate that favors rapid plant residue oxidation. Soil incorporation of plant residues with conventional disking will continue to accelerate the SOC decline. Decreases in SOC will contribute to a decline in soil quality, water holding capacity, and lower crop yields. On the other hand, conservation tillage, where plant residue is left on the surface, can increase SOC contents, especially near the soil surface. The USDA-ARS and Clemson University have established an Agroecology Program centered on improving soil quality and crop productivity through the development of innovative cropping and tillage practices. Descriptive information about the program including cropping, fertilization, pest management, and tillage practices can be found at(www.agroecology.clemson.edu). In a study, a 6.7-ha field was divided in half, with one side managed using innovative practices and the other using conventional techniques. Innovative tillage management practices include conservation tillage and planting transgenic varieties, while conventional management practices include disking in plant residue and planting conventional varieties. Prior to tillage, annual soil samples were collected by soil type at 0-3 and 3-15 cm depth increments from 100 locations. Sample SOC contents were measured using dry combustion/CO2 techniques. At 16 locations, soil bulk densities were measured annually while fields were under a corn and cotton rotation. After harvest, plant residue samples were collected for C-residue input estimates. Sampling sites were identified using GPS techniques to insure repeat sampling at the same locations. Preliminary results show that SOC contents were influenced by conventional and conservation tillage management systems. Conservation tillage caused a SOC enrichment in the top 3 cm, but a SOC declined in the 3-15 cm depth. At both soil depths, small SOC content variations occurred under conventional tillage. C-residue inputs and SOC residuals are being examined to link inputs with SOC dynamics.