Wednesday, 9 November 2005
4

Evaluation of Soil Quality and Crop Yields in a Black Oat-Crimson Clover Rotation under Conventional and Conservation Tillage Systems.

Y.G. Njitap and K. Kpomblekou-A. Tuskegee University, Tuskegee, AL 36088

Intensive crop production without proper rotations has contributed significantly to fertility decline of Alabama agricultural soils already low in CEC and SOM. Erratic rainfall patterns and decline in quantity of rainfall in Southern Alabama have made the matter worse by reducing the ability of farmers to grow and sell crops at competitive prices. Development and adoption of cropping systems will provide farmers with new tools to improve the economic, environmental, and health status of the state. We have initiated on-farm research activities designed to develop vegetable cropping systems that increase SOM and improve efficiency of organic N applications, reduce nutrient and soil losses through runoff. The study objectives were to evaluate the effects of cover crops and tillage systems on yields of sweet potato (SP) and sweet corn (SC) and to investigate the effect of soil management systems on selected soil quality parameters. The experimental design included factorial arrangements of two cover crops (Black Oat and Crimson clover), two tillage systems (conventional, CT and conservation, NT tillage), two fertilizers (mineral and broiler litter), and two vegetable crops (sweet potato, and sweet corn). The treatment combinations were replicated four times. The experiment was conducted at two sites (Shorter and Clayton) where soil climatic conditions are different. Every year, since 2002, cover crops are planted late in fall, killed in spring, and incorporated into the soil or left on soil surface as a mulch. Late in spring, SP or SC was planted. After harvest, plant yields are recorded and soil samples are taken at incremental depths for analysis (pH, bulk density, C, N, S, and SOM fractions). Results showed that in Shorter, SP yields were higher in broiler litter amended plots (31.8 and 40.2 t/ha under NT and CT, respectively) than in mineral fertilizer treated plots (16.8 and 13.3 t/ha, respectively).

Handout (.doc format, 60.0 kb)

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