Effect of short-term maize–cover crop rotations on weed emergence, biomass and species composition under conservation agriculture

Recent advances in crop production have identified crop rotation with cover crops as a key component of sustainable crop production. However, the implementation of conservation agriculture (CA) systems involving crop rotations in Zimbabwe is still minimal partly due to the anticipated increases in weed pressure. On-station field experiments using nine cover crops as treatments and maize as the control were done to study the effect of different maize-cover crop rotations on weed infestations under CA. Rotations involving velvet bean (Mucuna pruriens) and red sunnhemp (Crotalaria ochroleuca) significantly (p < 0.05) reduced weed density and biomass across seasons at the first weed count. Black sunnhemp (Crotalaria juncea) supported the highest gallant soldier (Galinsoga parviflora) and wandering jew (Commelina bengalensis) densities. It was concluded that short-term maize–velvet bean and maize–red sunnhemp rotations can reduce early-season weed density.