Influence of different N rates and intercropping methods on grain sorghum, common bean and soya bean yields

Abstract

Intercropping grain sorghum and legumes is a common practice in the tropics, but the effects of N application in an intercropping system have not been fully studied. Therefore, field experiments were conducted on a Decatur silty loam (Rhodie Paleudult) soil to evaluate the effects 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 interplanted, in alternate rows or alternating plants within rows, with common bean and soya bean. A sole planting (pure stand) of each species was added as a control treatment. Grain sorghum yield when intercropped with common bean and soya bean was 112% and 91 % of the sole planting yield, respectively. Yields of intercropped soya bean and common bean were 90% and 68% of their respective sole plantings. The yield difference between intercrop and sole crop sorghum became less as N rates increased. Sorghum yields and common bean responded positively to an increase in N from 0 to 99 kg ha-1. Efficiency of production from intercropped treatments, as measured by the land equivalent ratio, was significantly higher (1.83) than sole plantings.