Organic C dynamics and its conservation under wheat (Triticum aesetivum) – Mint (Mentha arvensis)-Sesbania rostrata cropping in sub-tropical condition of northern Indo-Gangetic plains

Soil organic carbon (SOC) is accumulated or depleted as a result of cropping and management strategies. It plays a significant role in maintaining soil quality, plant productivity and mitigating greenhouse gas emission. We studied the long-term (20 years) influence of a wheat-mint-Sesbania cropping system on the SOC stock. Estimates of stabilization of SOC in different pools and a tentative C budget were also developed. Twenty years of cultivation caused a decrease in SOC only in control soils, which received no manure and fertilizer. However, it increased with balanced use of NPK inputs. Soil C stock decreased significantly with increased in soil depth 0–15 cm to 15–30 and 30–45 cm. About 6% (−2 to+14) of the C added in crop residues and green manure were stabilized in the soil. On an average 12%, 14%, 59%, 15% of the water stable aggregates were in the >2 mm, 2.0–0.25 mm, 0.25–0.05 mm, and