ABSTRACT
Eight rotation systems involving cotton, corn, and soybean were evaluated at Stoneville, Mississippi from 1983 through 1988 to determine the effects of different rotational management systems on soil test levels of phosphorus, potassium, pH, organic matter, and exchangeable cations. Soil samples were taken each year following harvest and prior to any primary fall tillage operation. Soil test analyses results indicated some variations due to the different rotation systems. Soil pH was unchanged in systems dominated by corn as the acidity produced from high levels of nitrogen fertilizer was neutralized by alkalinity in the irrigation water. Where soybeans were included in the rotations, soil pH has increased. The soil organic matter content was not altered by the different rotations, The largest reductions in extractable P and exchangeable K+ were related to crop removal with the greatest removals associated with the grain crops as opposed to cotton.
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