8. Tropical lowland rice response to preceding crops, organic manures and nitrogen fertilizer.
Trop. Agric. (Trinidad), 69, 1, 1992, pp. 96-100
This study determined the effects of alternative crops grown late in the dry season on fertilizer N response of wet season irrigated rice and residual effects on dry season irrigated maize.
The experiment was initiated in 1984 on the farm of the International Rice Research Institute, Philippines, and repeated in 1985.
Five cropping sequences were examined:
- Green manure (Sesbania cannabina [Retz] Poir)
The experiment was laid out in a strip plot design with strips of crops in one direction and strips of N levels in the other. The treatments were replicated four times. Crop sequence and N level strips were re-randomized for each of the four replicates.
The soil of the experimental field was clay.
Mean rice grain yield without fertilizer N was maximum (4.5 t ha 1) after Sesbania and minimum 2.7 t ha-1) after maize fodder. Mean yields of unfertilized rice after FYM, fallow, and mungbean were intermediate, decreasing in that order. Yields of unfertilized rice grown after Sesbania, the aboveground biomass of which accumulated 70 kg N ha-1 (1984) and 98 kg ha-1 (1985) in 60 days were comparable with rice yields in fallow plots to which 44 and 96 kg ha-1 fertilizer N, respectively, were applied. FYM (15 t ha 1) supplied 68 kg N. The efficiency of N from FYM in combination with different N levels on rice ranged 31-51%.
Significant residual effects of FYM and green manure on the succeeding maize crop were not detected. Soil organic C and total N after wet season rice in 1985 were higher when Sesbania and FYM preceded rice compared with maize fodder, mungbean or fallow.
Crops in the tropics are often grown in a particular sequence.
Fertilizers and manures applied to one crop can affect the response of the succeeding crop.
To estimate optimum N fertilizer rates for crops grown in sequence, the effects of the preceding crop species and application of farmyard and green manures should be considered.
1245 92 - 12/71
Africa, Niger, semi-arid tropics, drylands, farm practices, field trials, pearl millet, cowpea, intercropping, soil fertility, crop productivity
REDDY, K.C. et al.
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