Influence of Intercropping Maize with Cowpea and Fertilization with Clinoptilolite on Forage Yield and Quality

Maize forage is poor in protein content which leads to low quality and nutritive value. Regarding the high feed costs of protein supplementations, legumes can be used in livestock nutrition for their high protein content, and thus, provide cost savings. In this study, maize (Zea mays L.) and cowpea (Vigna unguiculata L.) were intercropped in different sowing densities and fertilization with clinoptilolite and their monocropping equivalents were tested to determine the best intercropping system on forage yield and quality. Maize was cultivated alone (75,000 plants·ha^-1) and intercropped with cowpea as follows: 75,000 plants·ha^-1 of maize and 37,500 plants·ha^-1 of cowpea (MC₁), 75,000 plants·ha^-1 of maize and 50,000 plants·ha^-1 of cowpea (MC₂) and 75,000 plants·ha^-1 of maize and 75,000 plants·ha^-1 of cowpea (MC₃), in rows alternating with maize. The highest dry matter yield was produced by MC₃ (23.8 t·ha^-1), and the lowest by SM (20.7 t·ha^-1) in fertilization with clinoptilolite. All intercropped systems had higher crude protein contents, MC₁ (101 g·kg^-1 DM), MC₂ (108 g·kg^-1 DM) and MC₃ (117 g·kg^-1 DM), than the monocrop maize (84 g·kg^-1 DM) in fertilization with clinoptilolite. Intercropping of maize with cowpea and fertilization with clinoptilolite reduced neutral detergent fiber, resulting in increased forage digestibility. Therefore, maize intercropping with cowpea and fertilization with clinoptilolite could substantially increase forage quantity and quality, and decrease requirements for protein supplements as compared with maize monocrop.