Potential Utilization of Winged Bean as a Cover Crop

Abstract

In the present paper, we reported the potential utilization of winged bean (Psophocarpus tetragonolobus (L.) D.C.) as a cover crop to prevent erosion and to control weeds in abandoned fields. The yield of younger pods and mature seeds was estimated in the use as cover crop. Also the availability of winged bean residues as a green manure was tested after the younger pods were harvested as a vegetable crop.
The rate of covering over soil by winged bean which was 0.6 m² m^-2 in the inter-row area 12 weeks after sowing due to the slow initial growth increased with almost completely covering being achieved 12 to 32 weeks after sowing. Therefore, winged bean is considered to prevent erosion and control weeds from the rainy season to the typhoon season in Okinawa.
The total yield of the younger pods was 1.46 kg F. W. m^-2 from 28 weeks to 34 weeks after sowing. In addition, the yield of the dried seeds was 0.18 kg D. W. m^-2 in February after the younger pods had been harvested.
Moreover uptakes of N, P and K in the aboveground parts of the winged bean at the end of the harvest of younger pods amounted of 20, 2.7 and 6.3 g m^-2, respectively. It is concluded that a sufficient input could be achieved for use as green manure.