POTENTIALS OF MILLETTIA-THONNINGII AND PTEROCARPUS-SANTALINOIDES FOR ALLEY CROPPING IN HUMID LOWLANDS OF WEST-AFRICA

This study was conducted to assess the suitability of two fallow speci es that are indigenous to West Africa, M. thonningii (Schum and Thonn) and P. santalinoides (L'Her), for alley cropping with maize and their effect on soil chemical properties. It was carried out during the rai n-fed cropping season at Ibadan, Nigeria and Mbalmayo, Cameroon in 199 3 and 1994. Total dry matter of P. santalinoides prunings was higher a t the two sites than that of M. thonningii by about 35% to 37%. Maize, grain yield in plots supplied with prunings was significantly higher ( P < 0.05) than in control (no prunings or fertilizer application) at I badan. Grain yield in plots supplied with prunings plus 40 kg ha(-1) u rea fertilizer gave significantly higher yields than plots supplied wi th 80 kg N ha(-1) urea fertilizer only. At Mbalmayo, there was no sign ificant difference between grain yield in plots supplied with 80 kg N ha(-1) and plots supplied with prunings plus 40 kg N ha(-1) urea ferti lizer though the latter had higher yields. Grain yield was also higher in the middle rows than in rows adjacent to the hedgerows and these w ere not significantly different. Weed dry matter was reduced by 27% to 43% when Pterocarpus prunings were applied and 13% to 31% with applic ation of Millettia prunings. Weed flora in both locations changed from grasses to broad leaved. Soil chemical changes at soil depth 0 to 10 cm showed significant increases (pH, C, N, P and Ca) after two croppin g seasons in plots supplied with prunings or prunings plus fertilizer than the initial values. At Mbalmayo, K was lower after cropping in tr eatments than the initial values while at Ibadan, K and Mg were lower except in plots supplied with Pterocarpus prunings only. P. santalinoi des and M. thonningii have significant potential for agroforestry in t his sub-region.