Soil Quality, Resilience, and Crop Productivity Under 32-Year-Old Long-term Rice-Rice System in Acidic Alfisol of Assam

Rice-rice system is the foundation of food security in South Asian countries. Assessment of the quality and resilience of soil for sustaining productivity of the double rice system is extremely important under an impending climate change scenario. This study aims to evaluate the long-term effect of fertilization and manuring on the quality, resilience, and productivity of the soil. Samples were collected from 32-year-old long-term rice-rice cropping system situated at the Regional Rice Research Station of Assam Agricultural University (AAU), Titabar, Assam, from eight treatments, viz. control, 100% nitrogen (N), 100% nitrogen phosphorus potassium (NPK) zinc with sulfur (ZnS), 100% NPK zinc without sulfur (Zn-S), 50% NPK+50% green manuring (GM)-N, 50% NPK+50% farmyard manure (FYM)-N, 50% NPK+25% GM-N+25% FYM-N, and FYM at the rate of 10 t ha −1 at 0–15cm soil depth. Soil quality was assessed and soil resilience index (SRI) was calculated in terms of carbon mineralization with or without heat stress (48 °C for 24 h) and substrate addition (0.02 g glucose/g soil) and validated with soil quality index (SQI), soil organic carbon (SOC), and yield attributes. Available zinc (Zn), available potassium (K), acid phosphatase activity (ACP), and bulk density (BD) were selected as the key indicators of soil quality. Integrated treatment with 50% NPK+25% GM-N+25% FYM-N had the highest SQI. With an SRI value of 0.84, the 50% NPK+25% GM-N+25% FYM-N treatment was the most resilient to heat stress, whereas control soil was the least resilient. The SQI and SRI had a strong agreement (73%) with each other. Regression analysis between SRI and annual rice yield showed 73% agreement between each other. Integrated management practices may be recommended for rice-growing farmers in Assam for maintaining the quality, resilience, and productivity of the soil. Graphical Abstract