Growth and nutrient accumulation of winged bean and velvet bean as cover crops in a subtropical region

We examined biomass dry matter and nutrient uptake of live plant parts, leaf area index, and litter of winged bean (Psophocarpus tetragonolobus) and velvet bean (Mucuna pruriens) 12, 18, 24 and 30 weeks after sowing (WAS). The two plants had similar leaf and stem + petiole biomasses. At 30 WAS winged bean had a signifi cantly lower pod yield than velvet bean. Between 18 and 30 WAS, winged bean produced less litter than velvet bean due to differences in growth stages. The total mulch of live parts and litter of winged bean and velvet bean completely covered the ground by 18 and 12 WAS, respectively. Compared to velvet bean, the leaf and stem + petiole of winged bean had a signifi cantly higher N concentration; signifi cantly higher N uptake at 24 and 30 WAS; signifi cantly lower C/N ratio; and signifi cantly higher P, K and Mg concentrations. In winged bean, P uptake was signifi cantly higher in the leaf at 30 WAS and in the stem + petiole at all harvesting times. The total biomass of the leaf, stem + petiole and litter of winged bean was 317 -561 g DM m^-2, and their N content was 12.3 -17.7 g m^-2. The total biomass of live parts and litter of winged bean might be suffi cient to suppress weeds and increase soil N. Winged bean is an appropriate legume cover crop and green manure due to its longer growing period and superior ground-covering ability and high N input.