Tapping indigenous herbaceous legumes for soil fertility management by resource-poor farmers in Zimbabwe

A 2-year study was conducted in three rainfall zones of Zimbabwe to explore opportunities for harnessing biological nitrogen fixation of non-cultivated herbaceous legumes, which hitherto have been regarded simply as weeds, in order to improve soil productivity on smallholder farms. The rainfall zones used ranged from sub-humid (800 mm annually) to semi-arid (50 kg N ha-1. While such relatively small amounts of N input may not result in dramatic yield increases for subsequent crops, they may make a critical contribution towards reversing the highly negative nutrient balances prevailing on the fields of resource-poor farmers. Overall plant biomass yields wer