Productivity and nutrient balance of soybean (Glycine max)-based cropping systems as influenced by nitrogen levels in deep Vertisols of Central India

A field experiment was conducted on deep Vertisols during 2000–2001 to 2001–2002 to determine the production potential and nutrient balance of 3 cropping systems involving soybean [Glycine max (L.) Merr.], sorghum [Sorghum bicolor (L.) Moench] and their intercropping at 3 levels of fertility, viz. 0, 75 and 100% recommended dose of nitrogen (RDN) during rainy season (kharif), followed by wheat (Triticum aestivum L. emend. Fiori & Paol.] at 100% RDN during winter (rabi). Sole sorghum at 100% RDN recorded higher productivity, while the wheat productivity was highest when it was preceded by sole soybean at 100% RDN. However, sorghum - wheat cropping system at 100% RDN recorded the highest total productivity of 5,003 and 5,033 kg/ha of soybean-equivalent yield in 2000–2001 and 2001–2002 respectively. This cropping system recorded the total uptake of 475.9, 76.3 and 466.7 kg/ha of N, P and K, respectively, and resulted in a positive balance of 10.6, 4.9, and 12.4 kg/ha of available soil N, P and K, after 2 years. However, soybean-based cropping systems enriched the soil-N, especially with the application of recommended doses of N.