Split strategies and intercropping dhaincha for in situ green manuring and seed production in wet-seeded rice

Abstract

In a wet-seeded rice establishment system, it is feasible to raise dhaincha (Sesbania aculeata. W.) in alternate rows as an intercrop using a newly developed joint rice and green manure seeder. Intercropping dhaincha exclusively for in situ green manuring recorded a higher grain yield of rice (with green manure) than sole rice. Besides in situ green manuring, leaving every 20th row for seed production achieved not only the self manuring of the land, but also the self-production of green manure seed (dhaincha). Leaving dhaincha at narrow spacings (10th or 15th row) for seed production affected the growth, development and yield of rice in the adjacent rows. Within the total dose of fertiliser N, split dose of 25, 33, 21 and 21% at 20 days after sowing (DAS), at green manure incorporation (37 DAS), 55 DAS and 70 DAS were found to be the ideal method of N application, alleviating the temporary lock-up of N, if any, upon green manure incorporation. Thus, the sustainability of the green manure intercrop for in situ incorporation in the rice culture and of green manure seed production were proved by the study.