Use of cover crops to improve soil productivity: preliminary studies using tropical velvet bean

Abstract

Initial observations of a two-phase trial on the use of Mucuna deeringianum [M. deeringiana] to improve soil productivity are presented. In phase one, 42 seeds were sown at Kabete, Kenya, in October 1990 with 89% germination rate. By September 1991, 4 kg of beans had been harvested. The second phase studied the effects of M. deeringiana on improving crop cover and reducing soil loss at Mbooni and Kabete, resp. Initial observations show that the crop preformed fairly well, providing a cover of up to 25cm uncompressed thickness. Treatments on the runoff plots at Kabete include: bare ground (control), M. deeringiana; maize; the two crops intercropped and sown at the same time; intercropping with M. deeringiana sown one week after the maize; or intercropped with M. deeringiana sown two weeks after the maize. The highest soil loss was found on the bare plot (65 t/ha), followed by the intercropped plot with two weeks between sowing (50 t/ha). Soil loss was lowest in runoff plots with a pure stand of M. deeringiana (11 t/ha). Intercropping and sown at the same time provided highest percentage cover.