Pueraria phaseoloides (Roxb.) Benth, a legume, widely used as cover crop in plantations in the tropics, can contribute to increased food production. In association with food crops, pueraria can improve soil nutrient availability, stimulate soil biological activity, and control soil erosion, leading to high soil productivity. Under conditions in West Africa, pueraria has been shown to accumulate ... [Show full abstract] 150 to 250 kg N ha-1 within 4 to 18 mo of growth, of which 68% were derived from the atmosphere on P and K poor soil, and 87% when soil P and K supply was sufficient. Pueraria roots reach around 2 m, permitting survival during 5 to 7 mo of dry season and possibly contributing to the capture of nutrients in deep soil horizons. Pueraria fallow reduces the decline of soil organic matter under cropping and increases N concentration in particulate soil organic matter. Soil P absorption and requirement are reduced after pueraria fallow in the derived savanna. Pueraria fallow is more effective than the natural fallow in maintaining soil biological activity with higher microbial, earthworm, and microarthropod populations. Organic input from pueraria fallow and enhanced activity of soil biota by pueraria fallow resulted in a reduction in soil bulk density and an increase in aggregate stability. On an Alfisol in Southwestern Nigeria runoff and soil loss were reduced with pueraria residue mulch on yam mounds. On-farm research near Ibadan confirms that pueraria cover crop fallow has a positive effect on the subsequent food crop yield under farmer's conditions. The 8-yr cumulative net benefit was $1664 ha-1 for the pueraria fallow system, $1121 for the Chromolaena odorata natural fallow system, and $1113 for continuous cropping under farmer input in southwestern Nigeria. The pueraria fallow system was suitable on acid and non-acid soils with c1ay- and effective cation exchange capacity (eCEC)rich subsoil in the derived savanna and humid forest zones where maize is a dominant crop and fertilizer is not easily available.