Influence of Cotton + Legume Intercropping on Soil Health in Rainfed Vertisols Under High-Density Planting System

Although several intercropping systems have been reported for cotton, the effects of legume under high-density planting systems on soil biology and nutrient availability in rainfed Vertisol have not yet been studied. With this research gap, we performed a comprehensive evaluation of different legumes (black gram, cluster beans, cowpea, green gram, soybean) in cotton and studied their effects on soil biology and nutrient availability. Legume intercropping in cotton significantly decreased soil pH (4%) and calcium carbonate content (29%), indicating soil acidification. Significant enhancements in soil organic carbon (27%), mineralizable nitrogen (35%), available phosphorus (45%), sulphur (39%), and boron (21%) were observed in cotton + legume intercropping compared with the sole cotton. Legume intercropping significantly increased glomalin (24%), soil polysaccharide (16%), and soil phosphatase activities (58%). Among legumes, soybean and green gram exhibited higher beneficial activities. Overall, our study revealed the beneficial effects of legume-based intercropping in cotton. Among the legumes, soybean and green gram were superior in enhancing soil nutrient availability and biological activities.