INFLUENCE OF DIFFERENT N RATES AND INTERCROPPING METHODS ON GRAIN-SORGHUM, COMMON BEAN, AND SOYA BEAN YIELDS

Intercropping grain sorghum and legumes is a common practice in the tr opics, but the effects of N application in an intercropping system hav e not been fully studied. Therefore, field experiments were conducted on a Decatur silty loam (Rhodic Paleudult) soil to evaluate the effect s of N and intercropping methods on grain sorghum (Sorghum bicolor L.) with common bean (Phaseolus vulgaris L.) and soya bean (Glycine max L .). Four N rates (0, 33, 66, 99 kg ha(-1)) were utilized on sorghum in terplanted, in alternate rows or alternating plants within rows, with common bean and soya bean. A sole planting (pure stand) of each specie s was added as a control treatment. Grain sorghum yield when intercrop ped with common bean and soya bean was 112% and 91% of the sole planti ng yield, respectively. Yields of intercropped soya bean and common be an were 90% and 68% of their respective sole plantings. The yield diff erence between intercrop and sole crop sorghum became less as N rates increased. Sorghum yields and common bean responded positively to an i ncrease in N from 0 to 99 kg ha(-1). Efficiency of production from int ercropped treatments, as measured by the land equivalent ratio, was si gnificantly higher (1.83) than sole plantings.