Mungbean (Vigna radiata L. Wilczek) and cowpea (Vigna unguiculata (Walp)) intercrops and green manure for upland rice in Prafi, Manokwari, Indonesia
1995
Sukar
N accumulation was higher in the shoot than in the root or nodule. Uninoculated mungbean or cowpea did not produce nodule. Soil was a better planting medium than river sand. Available soil N sharply increased up to four weeks after biomass incorporation. Incorporating biomass of mungbean and cowpea at six weeks after planting improved the rice yield as compared to removing the biomass or using it as mulch. Soil N content declined with removal of the mungbean or cowpea biomass, while soil N slightly increased with the green manure as mulch. The N accumulated and added to the soil ranged from 165.8 to 274.7 kg N/ha when mungbean and cowpea were harvested at flowering stage, and between 61.42 to 137.77 kg N/ha when both crops were harvested at maturity for seed yield. Rice yield was significantly improved by adding inorganic N in all plots. The application of 90 kg N/ha of urea gained the highest grain yield among the intercropped plots. Mungbean and cowpea performed better when planted simultaneously with upland rice than when planted 7 or 14 days before upland rice. Monocrop rice yield was higher than intercrop rice with mungbean or cowpea. However, the efficiency of monocrop was lower, the land equivalent ratio of intercrop being more than 1.5. Considering the economic yield, intercropping performed better than monocropping, the latter resulting in negative profit. The highest profit was produced by the mungbean-upland rice intercrop planted simultaneously and without N-fertilization
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