Soil organic carbon sequestration potential of conservation agriculture in arid and semi-arid regions: A review

Conservation agriculture is increasingly adopted for efficient soil and water management in dry environments, yet their role in climate change mitigation through increased soil organic carbon (SOC) sequestration is not fully understood. This study reviewed the literature on SOC change in arid and semi-arid regions with the adoption of cover cropping, diverse crop rotations, and reduced or no-tillage management to elucidate the role of conservation practices on SOC sequestration. Published data between 1990 and 2021 were evaluated based on comparison counts and discussed in terms of percentage or mean change for SOC storage and sequestration potential. Results revealed mean SOC sequestration of 271 kg C ha−1 yr−1 and 235 kg C ha−1 yr−1 with cover cropping and diverse crop rotation, respectively, in the upper 30 cm soil depth. However, the SOC sequestration potential varied with soil type and tillage management. The SOC response to cover cropping or diverse crop rotation was more evident in medium-textured soils than other soils, in which diverse cropping systems with conservation tillage sequestered 10% more SOC than conventional tilled crop-fallow systems, greater than SOC sequestration with diverse cropping or conservation tillage alone. It was also noteworthy that the SOC sequestration rate was high in the first five years of adopting conservation practices and decreased as time passed until it reached a new equilibrium. The average SOC sequestration rate for studies <5 yr was highly variable across the arid and semi-arid regions, while the rate was low but consistent in the studies >10 yr. Conservation systems can benefit arid and semi-arid agrosystems by enhancing SOC sequestration; stacked conservation practices could effectively harness greater benefits.