Long-term Impact of Crop Residue Management on Lability and Thermal Sensitivity of Soil Organic Carbon under Wheat Based Cropping Systems

The study was conducted beginning from 2009 to 2020 (11 years) at ICAR-Indian Agricultural Research Institute, New Delhi, India to evaluate the long-term effects of various residue management practices (RMPs) on soil organic carbon (SOC) fractions in wheat based cropping systems in north-western India. A split-split plot design included four RMPs: biochar (BC) application, crop residue incorporation (CRI), crop residue burning (CRB), and complete residue removal (CRR), applied across three cropping systems: wheat-maize (WMCS), wheat-pearl millet (WPCS), and wheat-rice (WRCS). The study examined SOC mineralization, particulate organic matter carbon (POM-C), and oxidizable organic carbon (OOC) fractions. The findings reveal that BC application significantly enhances the stability of SOC, as evident from the higher activation energy (Ae) and Q₁₀ values, particularly in macroaggregates across different soil depths. Regardless of the cropping systems, the plots treated with BC had the largest percentage of macroaggregate associated POM-C in both the soil depths, specifically 5.67 g kg^-1 at 0–15 cm and 2.41 g kg^-1 at 15–30 cm. Furthermore, the findings demonstrated that the application of crop residue incorporation (CRI) and BC treatments consistently increase the amount of higher labile carbon (C) available in the soil, hence promoted nutrient cycling and microbial activity. In contrast, CRB and CRR treatments showed lower SOC stability and labile C contents. These results highlight BC’s potential as a sustainable residue management strategy (RMP) for boosting soil health and SOC sequestration in wheat based cropping systems.