Is maize-cowpea intercropping a viable option for smallholder farms in the risky environments of semi-arid southern Africa?

•Maize-cowpea intercropping had either no or a positive effect on maize yields.•Intercropping reduced cowpea yields by 5–35% when compared with the sole cowpea.•Maize had a larger root length density compared with cowpea allowing it to outcompete cowpea when intercropped.•Intercropping improved land-use productivity regardless of season quality and soil type.