Assessment of biomass, productivity and sustainability of soybean based cropping systems at three levels of nitrogen in deep vertisols of semi-arid tropical India

Abstract

In a 2-year field experiment (2001/02-2002/03) on deep Vertisols of Bhopal, India, the production potential, economic feasibility and nutrient balance of five cropping systems (soybean, sorghum and maize as sole crops, soybean + sorghum and soybean + maize as intercrops) each at 0%, 75% and 100% recommended dose of nitrogen (RDN) during rainy season were evaluated followed by growing wheat with RDN during post-rainy season. The results indicated that sole cropping of sorghum and maize recorded higher biomass yield than sole soybean and their intercrops. In contrast, the biomass yield of wheat during post rainy season was higher when the preceding crops were sole soybean or soybean + maize intercropping. At N0 level, intercropping of soybean + maize followed by wheat system was more productive and remunerative with a gain of 7.7 and 27.0 kg/ha of soil available P and K, respectively, but resulted in a net loss of 4.0 kg/ha of soil available N over a period of 2 years. This cropping system was less susceptible to runoff and soil erosion. At 75% and 100% recommended N levels, maize-wheat system was more productive and remunerative with a gain of 2.0 and 5.8 kg/ha of soil available N, 9.0 and 7.8 kg/ha of soil available P and 35.0 and 28.4 kg/ha of soil available K, respectively. However this cropping system resulted in higher runoff and soil loss. Adopting appropriate agronomic and soil conservation measures may correct the negative aspect of this system.