Forage legumes for improved fallows in agropastoral systems of subhumid West Africa. I. Establishment, herbage yield and nutritive value of legumes as dry season forage

A short-term improved fallow system based on forage legumes is suggested fo r crop-livestock farming systems in subhumid West Africa targeted to enhanc e soil fertility and dry season feed for cattle. At two sites, 13 legume sp ecies were compared with the natural fallow vegetation, the nutritive value of which typically fails to meet cattle requirements during the dry season . Establishment, dry matter yield and nutritive value of leguminous herbage in the year of establishment were evaluated as well as regeneration of leg umes after a cropping phase. Only a few species yielded more dry season her bage than the natural fallow, but most had considerably higher nitrogen con centrations (0.6-2.4% of dry matter) and in sacco dry matter digestibility (19-65%) than the natural fallow vegetation with 0.7-1.0% N and 28-30% DMD. In the mid dry season, Stylosanthes guianensis, Centrosema pubescens and A eschynomene histrix had the highest yields of 10 t/ha DM of standing herbag e plus shed leaves at one of the sites. The same species also showed good s elf-regeneration after a maize crop but were surpassed by other species wit h respect to nitrogen concentration and digestibility. The observed propert ies of the forage legumes are discussed with respect to their relative impo rtance for the targeted fallow system, and management alternatives are cons idered.