13. Grain yield responses in rice to eight tropical green manures.
Trop. Agric. (Trinidad), 69, 2, 1992, pp. 133-136
This study was undertaken to compare eight green manure legume species for biomass production, N accumulation and as substitutes for fertilizer
N in rice.
Crop residues and organic manures are common sources of humus and soil N. During the past few decades, organic manures were abandoned in favour of inorganic fertilizers that came with modern varieties of rice, maize (Zea mays L.) and wheat (Triticum aestivum L.), but owing to fertilizer input cost and concern for sustainable agriculture, interest in organic manures has been renewed. Farmyard manure, compost and green manure are commonly used organic manures, but farmyard manure and compost are limited in supply and generally low in nutrient content. Hence, re-examination of legume crops as a source of organic matter and N for rice is justified.
The treatments were arranged in strip plots with strips of green manures in one direction and N levels in the other. Eight green manure species were grown: dhaincha (Sesbania cannabina (Retz) Poir.); sunhemp (Crotolaria juncea L.); soybean (Glycine max (L.) Merrill); lablab (Lablab purpureus (L.) Sweet); indigo (Indigofera tinctoria L.); pigeonpea (Cajanus cajan (L.) Millsp.); cowpea (Vigna unguiculata (L.) Walp.); and mungbean (Vigna radiata (L.) Wilczek).
No fertilizer was applied to the green manures.
The green manures were incorporated in situ 60 DE by a tractor-mounted rototiller and by a power tiller-drawn mouldboard plough in 1985.
The above-ground biomass of Sesbania cannabina accumulated mean maximum N (84-199 kg ha-1) and indigo accumulated the least N (8-84 kg ha-1) in 30-60 days. Mungbean 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 4.0 t ha-1 in 1984 and 4.6 t ha-1 in 1985, comparable with 4.1 t ha-1 from 50 kg fertilizer N in 1984 and 4.7 t ha-1 from 105 kg fertilizer N ha-1 in 1985. In both years, 50-day Sesbania and Crotolaria acumulated 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 significant from Sesbania green manure in 1985. Soil organic C and total N were also significantly higher after Sesbania and Crotolaria than after other green manures or fertilizer N treatments.
1103 92 - 4/146
Asia, Philippines, study, field trials, intercropping, maize, mungbean,nitrogen,utilization efficiency, inoculation, land equivalent ratio
CHOWDHURY, M.K. and E.L. ROSARIO
[Ukrainian] [English] [Russian]