Optimizing crop straw management in China: valuing bioenergy potential and greenhouse gas reduction opportunities

Tailoring straw return strategies to specific regional conditions can optimize soil health, enhance crop yields, and contribute to climate change mitigation. By using the Rothamsted carbon model (RothC) and the bioenergy-emission-economic model (BEE), we assessed the spatially explicit, optimal straw harvest strategies to maintain soil organic carbon (SOC), and evaluated the climate benefits aquired from straw-based bioenergy. We found that the national average straw return rate needs to reach 43% to meet the 4 per mille SOC target. Most crop straws in Northeast China must be returned to cropland to maintain SOC level, while straws in East China and Central China could provide substantial quantities of biomass feedstock for energy production without SOC loss. Under future climate scenarios and designed straw harvest strategies, 0.3 to 0.7 Pg C of straw could become available annually for energy production, providing a greenhouse gas mitigation potential of 1.4 to 2.5 Pg CO₂e using the combined heat and power (CHP) and integrated gasification combined cycle (IGCC) technologies (2020-2100). These region-specific straw management strategies offer insights into sustainable agricultural practices, soil carbon enhancement, and agricultural sector’s climate policies.