Relay-planted green manures as a substitute for inorganic fertilizers for rice in the intensive cropping systems in Nepal. (422)
Keywords:Green manure, Intensive cropping system, Inorganic fertilizers, Rice, Sesbania aculeata, Vigna umbellata
AbstractIn the intensive cropping systems of Nepal, concern for sustainable soil productivity has emerged as an urgent issue. Farmer participatory on-farm research was carried out for two years (1993 and 1994) at two intensive cropping sites in the Western Hills of Nepal to investigate whether relay-planted green manures of Dhaincha (Sesbania aculeata) and rice bean (Vigna umbellata) can replace inorganic fertilizers in the lowland rice (Oryza sativa L.) intensive cropping system, and whether the relay-planted green manures affected the grain yield of the companion maize (Zea mays L.) crop. The two green manures were compared with the inorganic fertilizers applied at 60 kg N:30 kg P2O5:30 kg K2O ha-1, and compost applied at 10 t ha-1 as a local practice (control). The results of the two locations over two years showed that both green manures resulted in grain yields of rice equivalent to those obtained where inorganic fertilizers were applied and did not reduce the yield of the companion maize crop. Straw yield of the rice was significantly higher with the chemical fertilizer compared to the other three manure treatments. Rice bean was superior to Dhaincha in low soil moisture conditions. The practice of relay planting of green manures appears to be an alternative technology for sustaining rice yields in the intensive cropping systems and in low external input subsistence farming.