| Sub-Saharan Africa is perhaps the only major geographical region where famine and malnutrition still prevail and cause serious threat to humans. Socioeconomic and technical factors, including inadequate policies, economic backwardness, and alarming soil fertility decline, are believed to be the main causes for such threat.; Agroforestry technologies using leguminous shrubs and trees are reported to be effective in maintaining soil fertility through addition and cycling of nutrients, organic matter build up, and improvement of soil physical and chemical conditions. One such technology that has gained increased popularity in semiarid Africa is “improved fallows.”; The research presented here has the overall objective of examining the relevance of improved fallow technology as a land-management option for soil fertility improvement in southern Mali. In a series of on-farm and on-station experiments, we examined the technical aspects of the potential of three perennial species [Gliricidia sepium (Jacq.) Walp. (gliricidia), Pterocaxpus erinaceus Poir.(pterocarpus) and Stylosanthes hamata (L.) Taub. (stylosanthes)] for their suitability in improved fallows and soil fertility replenishment in the Koutiala region of southern Mali. Additionally, a linear programing model was used to assess the potential implications the adoption of such technology would have on the allocation of limited resources and on the end-of-year income of potential “early-adopter” households.; The findings indicated that although each species had some desirable characteristics for fallow improvement, none of them, taken alone, would be a perfect candidate for soil fertility replenishment in the region. The best opportunity may reside in a combination of species, especially gliricidia and stylosanthes. The application of the tree biomass to the soil during land preparation for sowing the crop resulted in satisfactory crop grain yields. Treatments receiving biomass of gliricidia + stylosanthes in mixture (in on-farm trials) and gliricidia and stylosanthes alone (in the on-station experiment) yielded more maize grain than the region's 1998 average yield of 2020 kg ha –1. However, considering the short-term nature of the experiments (two-year fallow duration), the results of the different soil tests (pH, N, available P, K, Ca, Mg, O.M., and CEC) were not conclusive in detecting any significant soil changes.; The gliricidia + stylosanthes improved fallows would only be of interest to for households using animal traction, which account for nearly 90% of the region's population, if they produce benefits other than improved grain yields such as fodder. |
