A review of mechanisms underlying soil carbon sequestration and enhancement strategies via diversified planting and green manure integration

Soil carbon sequestration plays a vital role in mitigating global climate change and sustaining crop productivity on farmlands. The key mechanisms underlying soil carbon sequestration on farmland involve chemical stabilization, physical protection, and microbial regulation. Soil hydrothermal conditions, soil physicochemical properties, soil enzyme activities, and soil microorganism communities strongly influenced these processes. Crop diversification is an important approach to improving soil ecological environments and enhancing carbon sequestration potential. In recent years, legume green manure integrated into major cropping systems has improved productivity, reduced carbon emissions, and promoted carbon sequestration. Incorporating green manure into a crop production system can reduce soil organic carbon (SOC) mineralization, increase SOC inputs, regulate soil aggregation processes, promote microbial biomass accumulation and residue formation, and improve microbial communities and their metabolic activity. These functions can be subdivided into three categories of physical, chemical, and microbial stabilization. The key technologies currently for enhancing soil carbon sequestration via diversified planting with green manure encompass selecting suitable green manure varieties, designing a sustainable diversified planting pattern, optimizing nutrient management to maximize synergies of green manure and other fertilizers, and cultivating carbon pool technologies that green manure combined with synergistic products. Future research should consider breeding specialized green manure varieties with high carbon sequestration efficiencies, improving the management of diversified planting with green manure, elucidating the synergistic mechanisms underlying microbial–aggregate–mineral interactions in soil carbon stabilization, establishing long-term monitoring systems to evaluate the role of green manure in soil carbon sequestration, and developing an integrated SOC management framework for diversified planting and green manure integration. This review provides theoretical insights and practical guidance for enhancing SOC sequestration and advancing carbon pool management on farmlands.