Alley Cropping in the Moist Savanna of West-Africa: I. Restoration and Maintenance of Soil Fertility on <'>Terre de Barre' Soils in Benin Republic

The potential of alley cropping systems to restore crop productivity on degraded land and to maintain crop productivity on a site recently cleared from a long-term fallow area in the derived savanna zone of southern Benin Republic was investigated. The hedgerow species were Leucaena leucocephala, Senna siamea, and Gliricidia sepium, and maize was used as the food crop. The trials were established in 1989 on the two sites with a different land-use history and soil type. Results showed that alley cropping increased crop production on the degraded site and maintained crop production on the nondegraded site, especially when S. siamea was used. Although substantial amounts of pruning biomass were added yearly to the soil, the general fertility status of the topsoil did not improve considerably except for the total soil nitrogen content of the S. siamea treatment on the nondegraded site.