The Effects of Sole and Traditional Intercropping of Millet and Cowpea on Soil and Crop Productivity

Summary The after effects of three years' continuous cropping with sole millet, sole cowpea or a traditional millet/cowpea intercrop were compared using five levels of nitrogen fertilizer. The continuous sole cowpea system had reduced the carbon to nitrogen ratio more than the continuous sole millet or the traditional intercrop. The test crop millet yielded much more, and its uptake of nitrogen and phosphorus was greater, when it followed sole cowpea than when it followed sole millet or the traditional millet/cowpea intercrop. The three years' continuous sole cowpea had an effect equivalent to the application of 205 kg N ha−1on the test crop of millet. It also caused the greatest reduction inStrigainfestation in the test crop. It is therefore recommended that cowpea cultivation be increased in the Sahel.