Investigations into the effects of some selected multipurpose trees on weeds and growth of maize (Zea mais (L.))and cowpea (Vigna unguiculata (L.)) in South-Western Nigeria

biomasa biomass biomasse crop performance crop yield escarda experimentation graine malezas mauvaise herbe mulch mulches multipurpose trees performance de culture rendement des cultures rendimiento de cultivos seeds semilla vigna unguiculata weed control weeds zea mays