Potentials of Millettia thonningii and Pterocarpus santalinoides for alley cropping in humid lowlands of West Africa

Abstract

This study was conducted to assess the suitability of two fallow species 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 rain-fed cropping season at Ibadan, Nigeria and Mbalmayo, Cameroon in 1993 and 1994. Total dry matter of P. santalinoides prunings was higher at 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 Ibadan. Grain yield in plots supplied with prunings plus 40 kg ha−1 urea fertilizer gave significantly higher yields than plots supplied with 80 kg N ha−1 urea fertilizer only. At Mbalmayo, there was no significant 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 fertilizer though the latter had higher yields. Grain yield was also higher in the middle rows than in rows adjacent to the hedgerows and these were not significantly different. Weed dry matter was reduced by 27% to 43% when Pterocarpus prunings were applied and 13% to 31% with application 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 cropping seasons in plots supplied with prunings or prunings plus fertilizer than the initial values. At Mbalmayo, K was lower after cropping in treatments than the initial values while at Ibadan, K and Mg were lower except in plots supplied with Pterocarpus prunings only. P. santalinoides and M. thonningii have significant potential for agroforestry in this sub-region.