WEED COMMUNITIES IN INTENSIFIED CEREAL-BASED CROPPING SYSTEMS OF THE NORTHERN GUINEA SAVANNA

The dynamics of weed populations were analysed in intensified cereal-b ased cropping systems of the northern Guinea savanna in Nigeria, A tot al of four common weed associations were identified through cluster an alysis. Five factors describing soil fertility conditions and field hi story best differentiated the weed communities according to a discrimi nant model. The analysis shows that maize-based cropping systems with a high frequency of cereal cropping and a low frequency of noncereal c rapping tended to be dominated by weeds such as Commelina spp. and Kyl linga squamulata. As soil fertility declined, Vernonia spp. and Eclipt a prostrata became more important. Increased frequency of noncereal cr ops in mixed cropping with cereals was associated with reduced inciden ce of weeds such as Leucas martinicensis, Oldenlandia corymbosa, Sperm acoce verticillata, Ludwigia hyssopifolia, Celosia laxa, and Ipomoea s pp. Further diversification of cereal-based systems to obtain a reduce d frequency of cereals is likely to increase the incidence of Dactyloc tenium aegyptium in crop fields. The information provides guidance for technology development and transfer on weed control for intensifying systems in the northern Guinea savanna of Africa. (C) 1995 European We ed Research Society