Grain yield responses in rice to eight tropical green manures
1992
Meelu, O.P. | Morris, R.A. | Furoc, R.E. | Dizon, M.A. (IRRI. Manila (Philippines). Multiple Cropping Department)
Eight legume species were evaluated as substitutes for fertilizer N for wet season (WS) rice in the Philippines. The aboveground biomas of Sesbania cannabina accumulated mean maximum N and indigo accumulated the least N in 30 to 60 days. Mungbeans and cowpea, which produced grain and crop residue, are potential dual-purpose grain and green manure species. Regardless of species, mean rice grain yield from green manures was 4t/ha in 1984 and 4.6 t/ha in 1985, comparable with 4.1 t/ha from 50 kg fertilizer N in 1984 and 4.7 t/ha from 105 kg fertilizer N in 1985. In both years, 60-day Sesbania and Crotalaria accumulated N in excess of the rice crop requirement. Residual effects from green manures on dry season (DS) rice were not significant in 1984 but were so from Sesbania in 1985. Soil organic C and total N were also significantly higher after Sesbania and Crotalaria than after other green manures or fertilizer N treatments.
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