Carbon sequestration, emission reduction, and technical strategies of rice-crayfish farming in central China.

Rice-crayfish farming represents a typical green and low-carbon alternative to rice monoculture. It is important to investigate the carbon sequestration and emission reduction effect of rice-crayfish farming to improve paddy soil quality, ensure food security, and address climate change challenges. In this study, we systematically evaluated the carbon sequestration and emission reduction effects of rice-crayfish farming through field experiment, carbon footprint assessment, and the DeNitrification-DeComposition (DNDC) model. Compared with rice monoculture, rice-crayfish farming increased the soil organic carbon (SOC) storage, and reduced the annual CH emissions, annual NO emissions, and global warming potential (GWP) by 6.4, 2.4 and 6.2%, respectively. Field engineering, nutrient management and regional variations contributed to differences in carbon emissions and carbon footprints associated with rice-crayfish farming. Moreover, reduction of CH emissions was pivotal for decreasing carbon footprint in rice-crayfish farming. DNDC model simulation revealed that the carbon sequestration potential of the rice-crayfish system is influenced by agronomic practices (planting pattern, area proportion of culture ditch, proportion of straw returning, nitrogen fertilizer application, tillage depth, and irrigation regime) and regional climate, landform, and soil. Optimized rice-crayfish farming exhibited varying carbon sequestration effects across different regions. Conversion from rice monoculture to optimized rice-crayfish farming altered the regional carbon sequestration and source dynamics. This study provides a rationale for developing tailored strategies to maximize carbon sequestration and minimize carbon emissions at the regional or farm scales.