Cover crops for soil carbon sequestration and sustainable agroecosystem: a review of ecological processes

Cover crops are increasingly promoted as a pillar of climate-smart agriculture due to their potential to improve soil organic carbon (SOC) sequestration, improve soil health, and regulate agroecosystem resilience. However, reported gains in SOC are inconsistent, and a fragmented understanding of the underlying mechanisms has hindered a clear evaluation of their long-term stabilization potential. This review summarizes the recent literature on the various functions of cover crops in the soil carbon cycle, nutrient cycling, and ecological processes. Cover crops can enhance SOC sequestration in numerous ways, such as through above- and belowground biomass inputs, root protein exudation, and microbial necromass. They also help in carbon stabilization by improving soil aggregation and physical protection of soil organic matter. Cover cropping leads to an average of 7–8% increase in SOC stocks and 15% increase in water-stable aggregates, with these effects differing based on climate, soil properties, cover crop species, and management approach. Biologically, cover crops contribute to soil biodiversity, microbial activity, and habitats of useful organisms that facilitate natural pest control and weed control. Notwithstanding these advantages, there are certain drawbacks, such as possible water use trade-offs and inconsistent effects across agroecosystems. This review emphasizes the diverse benefits of cover crops for sustainable agricultural production, climate change mitigation, and ecosystem resilience. The future studies should focus on long-term, system-based, and region-specific studies to quantify the carbon stabilization mechanisms and optimize cover cropping management in different agroecosystems. Cover crops increase global soil organic carbon stocks by 7–8%. Water-stable aggregates increase by 15% under cover crop management systems. Soil organic carbon sequestration rate ranges from 0.24–0.32 Mg C ha⁻¹ yr⁻¹ Cover crops enhance microbiomes (up to +24%) and soil biodiversity. Cover crops enhance soil structure, water storage, and decrease soil erosion. Legumes also fix nitrogen, reducing synthetic N fertilizer by 30–50%.