Tuesday, November 14, 2006

Crop Rotation and Tillage System Effects on Particulate Soil Organic Matter.

K. Kpomblekou-A and Gyresse Njitap. Tuskegee Univ, 210 Campbell Hall, Tuskegee, AL 36088

Crop production in south central Alabama has been primarily limited by poor soil quality and erratic rainfall. Intensive use of farmland for crop production without crop residues returns and deep plow have contributed considerably to soil fertility decline. Because of the importance of soil organic matter (SOM) in soil health, on-farm research activities were designed to develop vegetable cropping systems that would increase SOM and improve efficiency use of broiler litter (BL) application to farmland. Several studies have documented the benefits of judicious use of manures in maintaining soil quality and enhancing crop productivity. The goals of the present studies were to conduct research that educates farmers on utilization of BL and incorporation of cover crops into crop rotations. The objective was to investigate the dynamics of particulate SOM in a sweetpotato-sweet corn rotation under conventional and conservation systems. The experimental design included factorial arrangements of two cover crops (black Oat and crimson clover), two tillage systems (conventional tillage, CT and reduced tillage, RT), and two fertilizers (NPK and BL). The experiment was conducted in four replications at two sites (Shorter and Clayton) where soil types and climatic conditions differ. Prior to establishment of the plots, core soil samples were collected at 0-15 cm depth and analyzed for nutrient contents and lime requirements. Every year since 2002, cover crops were planted late in fall and incorporated into the soil in spring or left on soil surface as a mulch. Sweetpotato or sweet corn was grown and harvested. Yields were recorded and soil samples were taken at incremental depths (0-1, 1-2, 2-3, 3-5, 5-10, and 10-15) for analysis of organic C, organic N, and particulate SOM. Results showed that the RT system increased C sequestration (1.3%) compared with the CT system (0.40%).