Effects and mechanisms of cover crops on yield enhancement, resource efficiency, carbon sequestration, and emission reduction in southern China's multi-cropping systems

The southern part of China abounds in water and heat resources. Developing multiple cropping systems in this region has long been recognized as a crucial strategy for safeguarding national food security. The expansion of these systems has driven the rapid growth of cover crops, positioning the region as a key production area for cover crops in China. Recently, many studies have shown the critical role of cover crops in addressing challenges such as low resource use efficiency, high greenhouse gas emissions, and soil degradation in southern China’s intensive cropping systems. However, the adoption of cover crops remains at an early stage, hindered by disorganized planting practices, inflexible cultivar selection, and limited farmer adoption within complex multiple cropping regimes. Furthermore, existing research has predominantly focused on isolated factors, leaving the synergistic mechanisms underlying cover crops’ dual benefits of yield enhancement and carbon sequestration poorly understood. This review systematically examines the current status, challenges, and research advancements in cover crop integration within southern China’s multiple cropping systems. Key mechanisms by which cover crops enhance productivity and sustainability are analyzed, including: increasing exogenous organic matter input to improve soil physicochemical and biological properties; fostering synergistic interactions with primary crops under intercropping or rotation systems; and reducing agricultural inputs while optimizing resource use efficiency. Finally, in light of the issues currently present in the development of cover crops, we suggest that when implementing the cultivation of cover crops in this region, measures should be taken to suit local conditions and seasonal factors. Starting from the regional characteristics and integrating the actual cropping systems with the dominant cultivated crops, appropriate cover - crop varieties and planting patterns ought to be chosen. By elucidating the synergies between yield efficiency and soil carbon sequestration, this study aims to provide a theoretical foundation and practical insights to guide the green development and scalable adoption of cover crops in southern China’s agricultural systems.