The role of legume fallows in intensified upland rice-based systems of West Africa

摘要: Traditional upland rice-based cropping systems in West Africa rely on periods of fallow to restore soil fertility and prevent the build-up insect pests weeds. Demographic growth increased demand for land is forcing many farmers intensify their rice production systems. Declining length increasing number crops before leaving extended result a significant yield reduction. Promising system alternatives include use site specific, weed-suppressing, multi-purpose cover legumes as short duration fallows. Constraints related intensification were determined 209 farmers' fields four agro-ecological zones during 1994 1995. Nitrogen accumulation weed suppression evaluated 54 legume accessions, grown six months dry season, under range hydrological conditions 1994/95. Their effect was To increase benefits from improved technology, timing establishment relation crop removing, burning, mulching, or incorporating residues prior determined. Intensified resulted plot-level reduction that highest derived savanna bimodal forest where it associated with doubling biomass N supply. Legume fallows appear offer potential sustain yields intensified cropping. most instances significantly greater than weedy control several species suppressed growth. by varied between 1–200 kg ha-1 30–90% Ndfa. Rice grain following an average 0.2 mg 29% above control. Relay substantially biomass. However, seeding at 28 days earlier reduced due interspecific competition. Incorporating mulching provided no advantage compared burning. Absolute effects function site, species, management practice.