Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 6/8/2004
Publication Date: 6/8/2004
Citation: Franzluebbers, A.J., Grose, B., Hendrix, L.L., Morse, R.D., Wilkerson, P.K., Brock, B.G. Surface soil organic pools in response to silage cropping intensity under no tillage. Annual Southern Conservation Tillage Conference for Sustainable Agriculture. 2004. p. 76-84. CD ROM. Raleigh, NC. Interpretive Summary: Continuous silage production returns little crop residue to the soil, leading to little surface residue to protect soil against equipment traffic and erosion. Surface residue is also important to feed soil microorganisms for successful biological control of diseases and effectively cycling of important plant nutrients. Scientists at the USDA Agricultural Research Service in Watkinsville GA and Virginia Polytechnic and State University are collaborating with the USDA Natural Resources Conservation Service and a dairy producer in Iredell County North Carolina to study the impact of three cropping systems (a gradient in residue returned to soil) on soil organic matter, soil physical properties, and crop productivity. Reducing the amount of silage harvested from two crops per year to only one crop per year had a major positive impact on soil organic matter. A third cropping system that produces only one silage crop every two years did not improve soil properties any more dramatically than the one silage crop per year. These results can help dairy producers in the southeastern USA to determine an optimum balance between short-term economic returns and longer term investments in improved soil quality for more sustainable production.
Technical Abstract: Although reduced tillage itself is beneficial to soil quality and farm economics, the amount of crop residues returned to soil will likely alter the success of a particular conservation tillage system within a farm operation. There is a need for more information on multiple-year impacts of different residue retention systems on surface-soil organic matter pools in different environments. We investigated the impact of three cropping systems (a gradient in residue returned to soil) on total organic C and N, particulate organic C and N, microbial biomass C, and mineralizable C and N in a Piedmont soil in North Carolina. There is an inverse relationship between silage intensity and residue returned to soil. With time, surface soil organic matter pools became higher with reduced silage cropping intensity as a result of greater crop residue returned to soil. These results suggest that greater quantities of crop residue returned to soil have positive effects on soil organic matter pools in continuous no-tillage crop production systems. These results can help to determine an optimum balance between short-term economic returns and longer term investments in improved soil quality for more sustainable production.