Effects of long-term nutrient management in semi-arid Vertisols on soil quality and crop productivity in a cotton-greengram intercropping system

Systematic research on the long-term effects of integrated nutrient management (INM) on soil quality and crop productivity, particularly in semi-arid climates, is limited. However, such research is essential, particularly for smallholder farmers in semi-arid regions, to address the triple challenges of sustainable agriculture, food and fiber security, and environmental degradation. This study aimed to investigate changes in soil quality and cotton-greengram system productivity following long-term nutrient management and to establish a quantitative relationship between the soil quality index and system productivity. A study was conducted from 2017 to 21 in a long-term field experiment initiated in 1987 with eight treatment combinations, including sole organics (½NFYM, ½NGli), inorganics (NPK, ½NK), and the integration of organics to substitute for the fertilizer-N requirement (INM) [(N + NGli)PK, (N + NFYM)PK, (NGli)PK] in the cotton-greengram intercropping system of the semi-arid region in Maharashtra, India. Surface soil samples (0–0.2 m) were collected and analyzed for different physical, chemical, and biological properties to develop a soil quality index. The soil quality index was then validated against the system productivity. The INM treatments, where 50 % N was substituted by Gliricidia [(N + NGli)PK] or FYM [(N + NFYM)PK], demonstrated significantly higher cotton-greengram system productivity, sustainable yield index, and soil quality index, while the lowest values were observed in the control. Soil organic carbon (SOC), available nitrogen (N), mean weight diameter, and alkaline phosphatase were identified as the key soil quality indicators. The predictive relationship between system productivity and soil quality index revealed that maintaining 6.5 g kg-1 (chromic acid oxidizable) SOC and 253 kg (potassium permanganate oxidizable) available N ha-1 in the soil of semi-arid climates is crucial for sustaining cropping system productivity. INM that encourages balanced fertilization must include partial N supplementation by FYM/Gliricidia as part of the nutrient application package in semi-arid Vertisols. Our study highlights the significance of adopting sustainable agricultural practices to achieve optimal soil conditions for maximum productivity in semi-arid regions. This knowledge can benefit farmers and researchers globally in optimizing INM practices for different crops and agroecological zones, aiding in the development of sustainable farming strategies and ensuring food-fiber security while preserving soil quality and protecting the environment.