Diversifying maize-based systems with legumes and strip cropping in sub-humid Zimbabwe

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Abstract Maize ( Zea mays L.) is an important crop in Zimbabwe, but the grain yields achieved are often only one tenth of their estimated potential. Low grain protein content and low biomass yields further constrain food quality and livestock feed availability on smallholder farms. To assess whether integrating legumes into maize-based cropping systems could improve yields, yield stability, and biomass, calorie and protein production, we tested six cropping systems in rainfed conditions under conservation agriculture in central Zimbabwe in two identical field experiments on soils with contrasting textures. The cropping systems included maize monoculture, maize rotated with pigeon pea ( Cajanus cajan L. Millsp.) or cowpea ( Vigna unguiculata L. Walp.), maize-pigeon pea intercropping, and double-row strip crops of maize with pigeon pea or cowpea. Each system was tested with and without fertilizer (basal application 12 kg ha −1 N, 14 kg ha −1 P, 8 kg ha −1 K, plus two topdressings, each 26 kg N ha −1 ). Mean grain yields were highest in rotations (maize = 2855 kg ha −1 , pigeon pea = 752 kg ha −1 , cowpea = 567 kg ha −1 ). Rotations also had a high maize yield stability, comparable with the monoculture. However, total biomass, calories, and protein per hectare were highest in maize-pigeon pea strip cropping (5945 kg ha −1 , 9.14million kcal ha −1 , and 308 kg ha −1 , respectively). Across all cropping systems, fertilizer enhanced system productivity, increasing maize yields by 88% on average. Overall, maize-pigeon pea strip cropping produced the most food and feed per unit land area, in both fertilized and unfertilized conditions.