Intercropping or rotation with leguminous crops such as cowpea is important for nitrogen fixation and for controlling striga. Millet and sorghum yield in continuous cropping diminishes over the years, but millet/cowpea or sorghum/cowpea intercropping are more sustainable systems. Farmers often practice millet/cowpea intercropping, but the density of the cowpea is often low; hence, the residual effect of the cowpea is low. In semi-arid regions in Nigeria, farmers plant cowpea with a much higher density than is found in Mali and in Niger. This difference may be linked to the existence of a well developed cowpea market in Nigeria. In Sahelian countries, there is often a lack of good quality seeds.  

It is recommended to plant millet/ sorghum and cowpea in alternate rows or to alternate 4 rows of cowpea with 2 rows of millet. The following year, either millet or sorghum is planted in those rows where cowpea had been cultivated the previous year. With the cowpea-millet rotation, about 10 to 15 kg of nitrogen per hectare is added if the haulm is not retained in the field. It is often necessary to protect the cowpea with two insecticide sprayings.

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