On-farm Preliminary Study on the Possibility of Establishing soybean as Sole Crop or Intercropping with Rice under Saturated Soil Culture

Abstract

A preliminary study on the possibility of planting soybean as sole crop or intercropping with rice under soil saturated condition was conducted in the farmer’s field at Krub yai Sub-district, Banpong district of Rachaburi Province. Split-split plot design with three replications was used in this study. Main plots consisted of soybean planted as sole crop and intercropping with rice in the soil saturated condition plus soybean planted as sole crop under normal irrigation scheme. Sub-plot consisted of three cultivars of soybean viz S.J.4, Nakornsawan 1 and A 138, and sub-sub plot consisted of with and with-out nitrogen fertilizer. Ammonium sulfate at the rate of 2.4 kg N/rai was applied at planting to soybean in nitrogen fertilizer treatment. The study was conducted between August-December 1989. The result of the study revealed that under soil saturated condition soybean planted as sole crop gave higher yield than those intercropped with rice. Under soil saturation, soybean gave significantly higher yield than those receiving normal irrigation scheme. Cultivar A 138 gave the highest yield among other cultivars tested and the effect of nitrogen fertilizer was not found. Rice intercropping with soybean gave significantly lower yield than rice planted as monoculture. Land equivalent ratio (LER) of soybean intercropping with rice was higher than monoculture cropping of rice and soybean. Gross income of soybean intercropping with rice was found to be highest among other treatments. However, based upon gross income derived only from soybean, it was found that soybean planted as sole crop under soil saturation gave the highest gross income. Cultivar A 138 gave the highest gross return than other cultivar used in this study.