• Fertilizer use and legume crops have almost doubled total annual nitrogen inputs to global terrestrial ecosystems

• Mitchell and Entry (1998) found that long-term planting of legumes as a winter cover crop resulted in higher soil organic carbon levels compared with treatments that did not include a winter cover crop.

• Vigna unguiculata (cowpea), Vigna subterranea (Bambara groundnut), Macrotyloma geocarpum (Kersting?s bean) are the major indigenous legumes cultivated throughout Sub-Saharan Africa.