Long-term conservation agriculture to enhance soil properties and quality in rice–wheat cropping system

Conservation agriculture (CA) presents a promising substitute to the tillage-intensive rice-wheat cropping system (RWS) prevalent in the Indo-Gangetic plains (IGPs). In the northwestern IGPs, on-farm studies examining the impact of CA durations on soil properties and quality are limited. This study assessed the effects of CA practised for 2 (CA2), 4 (CA4), 8 (CA8), and 12 (CA12) years and conventional tillage (CT) on soil quality in the Nilokheri block of Haryana, India. The collected soil samples from 0-5 to 5-15 cm were analyzed for 22 different soil parameters, and a soil quality index (SQI) was developed using principal component analysis (PCA) for each scenario. The results showed that scenarios CA8 and CA12 had 9.8-10.7 and 11.1-11.3% lower bulk density, respectively, compared to CT. Mean weight diameter, saturated hydraulic conductivity, and water holding capacity were significantly higher in CA8 and CA12 over CT at both soil layers. Microbial biomass carbon and dehydrogenase activity increased by 32 and 42.7%, 14.9 and 32.3% in CA8 and CA12, respectively, over CT in the surface soil. Most of the chemical parameters were significantly influenced by CA, except for pH, electrical conductivity, and available Cu. Key soil quality indicators identified through PCA included Ks, WHC, β-glucosidase activity, dehydrogenase activity, available S, available Fe, and available Cu. The highest SQI was observed in CA12, followed by CA8 and CA4, and the lowest in CT at both depths. The derived regression coefficients revealed a strong positive relationship between SQI and both rice equivalent yield and wheat yield. This finding highlights the potential of enhancing soil quality to boost agricultural productivity under CA, thereby fostering sustainable farming. Such improvements are vital for building climate-resilient cropping and supporting the widespread adoption of CA practices. Therefore, it may be concluded that adopting CA for more than 8 years could help restore soil health and sustain productivity in the rice-wheat cropping system of northwest IGPs.