Soil Quality Assessment under Long-term Soil and Nutrient Management Practices in Vertisols of Kovilpatti

In order to assess the impact of integrated nutrient management (INM) treatments on soil quality, two ongoing long-term experiments at Kovilpatti centre of All India Coordinated Research Project for Dryland Agriculture were adopted. Under each experiment, 19 soil q uality indicators were assessed. In experiment 1, the key soil quality indicators identified and their per cent contributions towards soil quality were: electrical conductivity (19%), available N (23%), P (18%), S (8%), microbial biomass carbon (MBC) (10%) and labile carbon (22%). The relative order of performance of INM treatments in terms of soil quality and their soil quality index (SQI) values were: T5: 40 kg N ha⁻¹ + 20 kg P ha⁻¹ + 25 kg ZnSO₄ ha⁻¹ (2.80) = T4: 50% N (urea) + 50% N as farm residue (2.69) = T3: Farm Yard Manure (FYM) to meet 20 kg N ha⁻¹ + 10 kg P ha⁻¹ (2.65) = T2: 40 kg N + 20 kg P ha⁻¹ (2.49) = T6: Farmers method (FYM 5 t ha⁻¹) (2.44) = T1: Control (2.26). In experiment 2, the key soil quality indicators identified and their per cent contributions towards soil quality were: P (20%), S (16%), Fe (22%), Mn (10%), MBC (8%) and bulk density (24%). The order of superiority of the INM treatments in terms of soil quality along with their SQI values was: T5: 40 kg N ha⁻¹ as FYM + 20 kg P ha⁻¹ as SSP (1.93) > T3: 40 kg N as urea + 20 kg P ha⁻¹ as SSP (1.85) = T6: 20 kg N as urea + 20 kg N ha⁻¹ as FYM + 10 kg P ha⁻¹ as SSP (1.75) = T7: 20 kg N as urea + 20 kg N ha⁻¹ as FYM + 20 kg P ha⁻¹ as SSP (1.72) = T2: 40 kg N as urea (1.65) = T4: 40 kg N ha⁻¹ as FYM (1.63) > T1: Control (1.38).