Competitive behaviour of different legumes grown as intercrop with direct seeded upland rice

Abstract

A field experiment entitled "Competitive bahaviour of different legumes grown as intercrop with direct seeded upland rice" was conducted at the Instructional Farm, College of Agriculture, Vellayani from June 2001 to October 2001. The study aims to find out an optimum row proportion of upland rice to legume combination, to assess the soil fertility improvement and to evolve an economically feasible legume intercropping system in upland rice. The experiment was laid out in randomised block design with ten treatments in three replications. The weather condition during the cropping period was congenial for crop growth. The treatments were sole crops of upland nee, blackgram, greengram and cowpea, intercropping of upland rice with blackgram, greengram and cowpea in 2 : 1 and 3 : 1 ratios. The results of the study indicated that the legumes performed well under intercropped condition than under sole crop situation by dominating the cereal component rice. The association of legumes excepting greengram had complementary effect on rice and it was proved that blackgram or cowpea can be grown in a compatible manner with rice. - . The sole crops produced significantly higher seed yield than the intercropping systems, in which yield varied due to differences in population. The sole crops recorded the maximum nutrient uptake over the intercropping treatments. The competitive behaviour of the components and the bio- economic suitability of the intercropping systems were studied. Higher LER, LEC, RCC and rice equivalent yield were obtained in rice + cowpea in 2: 1 ratio. The highest competition ratio and the highest aggressivity values were 0 btained in rice + greengram in 2: 1 ratio. lA-I The results on monetary returns were higher in intercropping systems except greengram intercropping compared to sole crop of rice. The highest gross returns, net returns and benefit cost ratio were realised from the rice + cowpea intercropping system in 2: 1 ratio. Among the sole crops, cowpea gave higher monetary returns and benefit - cost ratio. The maximum net returns (Rs. 11080 ha ") was obtained when rice and cowpea were grown in 2: 1 proportion. Greengram intercropping with rice was not profitable. In general, the soil nutrient status indicated a significant positive buildup of nitrogen, phosphorus and potassium in all legume included plots where legumes were incorporated into the soil after the final harvest. Thus, raising cowpea or blackgram as an intercrop in upland rice appears to be more profitable. Under the circumstances, where an intercrop is desired for yield stability, to reduce risk or to get yield diversity, raising cowpea and rice in 1:2 proportion can be recommended as an economically viable and biologically sustainable practice.