Climate-management interactions drive soil organic carbon sequestration potential in China's croplands during 2020–2060

Soil organic carbon (SOC) sequestration in croplands plays a vital role in mitigating climate change and enhancing soil fertility. As one of the world’s leading agricultural nations, China’s croplands exhibit highly representative climate types, soil conditions, crop varieties, and farming systems on a global scale. Despite extensive studies on SOC dynamics, the spatial variability of SOC sequestration potential remains insufficiently quantified across China's diverse agricultural regions, which adopt varying straw management practices. This study employs a process-based modeling approach to systematically assess the dynamics and sequestration potential of SOC in China’s croplands (122.4 Mha) from 2020 to 2060. We found that by sustaining a moderate historical management during 2015-2020 (i.e., an average of approximately 37% residue retention rate in addition to traditional root residue retention and farmyard manure application), China’s croplands SOC stock is projected to increase by more than 25% by 2060, corresponding to total SOC sequestration of approximately 1,650 Tg C at the national scale. Regional variability exists, with southern China (e.g., east and central, south and central, and southwest regions) contributing to approximately 84% of total SOC sequestration, while northeast region has minimal sequestration potential. Carbon inputs, temperature, and precipitation are positively correlated with SOC dynamics, while initial SOC density (SOC D ) shows a negative partial correlation with changes in SOC. This study not only characterizes the dynamics of SOC in China’s croplands over the next 40 years under different carbon management practices and climate change scenarios, but also presents the pathways for achieving sustainable carbon sequestration in future croplands. Our findings highlight the importance of sustaining and optimizing straw return practices, alongside region-specific strategies, to maximize SOC sequestration and support global climate mitigation goals. • The potentials of cropland soil to sequester additional carbon under varying climate-residue management scenarios in China are quantified. • A minimum 30% straw return rate is essential to sustain the nation-level cropland soil organic carbon sequestration to meet the '4 per 1000' initiative target. • The magnitude of carbon inputs outweighs both climatic and edaphic factors in determining future SOC sequestration potential. • China's croplands could sequester approximately 1,650 Tg C by 2060.