[Strategies for enhancing soil organic carbon in rice-wheat rotation farmland: A meta-analysis]

Soil organic carbon (SOC) is a critical indicator for maintaining ecosystem functions and mitigating climate change in farmlands. To address soil degradation caused by long-term intensive cultivation in rice-wheat rotation farmland, we collected data from 86 field trial papers published before December 2024, and conducted a meta-analysis to systematically analyze the effects of organic fertilizer application, straw returning, conservation tillage, and reduced fertilization on SOC, as well as their driving factors. Results showed that, compared to their respective controls (no fertilization, straw removal, and conventional tillage), the application of organic fertilizers, straw returning, and conservation tillage significantly increased SOC content by 21.2%, 13.0%, and 4.2%, respectively. Notably, the addition of organic fertilizer after conventional fertilization yielded the highest increase of SOC, while reduced fertilization led to a significant 6.1% decrease in SOC. Furthermore, the combination of straw returning and conservation tillage exhibited a synergistic effect, increasing SOC by 18.6%. The effects of management practices on SOC were significantly regulated by environmental factors. Straw returning demonstrated stronger SOC enhancement under conditions of mean annual temperature >18 ℃ and in alkaline soils, whereas organic fertilizer application showed greater improvement effects in alkaline soils with initial SOC≤12.1 g·kg^-1 and bulk density>1.31 g·cm^-3. Our results elucidated the effects of different management practices in rice-wheat rotation farmland on enhancing SOC, providing a scientific basis for developing differentiated carbon sequestration strategies in major production regions of East and South Asia.