The Soil Fertility Improvement and Soil Amendment Innovation Team at the Institute of Agricultural Resources and Regional Planning (IARRP), Chinese Academy of Agricultural Sciences, recently reported advancements in utilizing crop straw resources. By synthesizing 464 comparison data sets from 126 peer reviewed publications, the team mapped the spatial distribution of straw humification coefficients across China's major climatic zones and identified the primary factors shaping these patterns. The study highlights a strong link between straw decomposition rates and soil carbon–nitrogen status, nitrogen application rates, and regional climate, supporting China's goals in green agricultural development, farmland quality enhancement, and the national "carbon peaking and carbon neutrality" strategy. The findings were published in the "Journal of Environmental Management".

Straw incorporation is a key component of agricultural carbon sequestration. China produces a large amount of crop straw every year, and its effective utilization is not only essential for improving soil fertility and stabilizing agroecosystem functions but also closely tied to agricultural emission-reduction and carbon-sink goals. During decomposition, some straw-derived carbon becomes stable and is retained in soil through humification, making the straw humification coefficient key to long-term carbon-sequestration potential and soil quality improvement. However there has been little systematic analysis on the key factors affecting straw decomposition in different climate zones. This information is essential for, and crucial to, developing the best nutrient management strategies, and for the effective utilization of straw.

The study found substantial regional differences: the straw humification coefficient in mid-temperate, warm-temperate, and subtropical regions averaged 0.392, 0.319, and 0.356, corresponding to natural annual decomposition rates of approximately 61%, 68%, and 64%, respectively. The warm-temperate zone exhibited the fastest decomposition rate—driven not by climate alone, but by the combined influence of favorable hydrothermal conditions and soil nutrient status. The researchers highlighted that relying solely on climate to infer straw decomposition potential may lead to management biases; instead, soil nutrient levels and nitrogen availability must also be considered.

The study further revealed a "dual-threshold effect" of nitrogen input on straw humification, varying across both regions and soil types. These insights provide a scientific basis for developing China's policies on straw return, soil fertility improvement, and regional agricultural carbon-management schemes. The findings also offer research support for ecological farmland construction, emission-reduction and carbon-sink initiatives, and strategic land-protection programs. The team recommends strengthening long-term monitoring and regional model validation to guide the establishment of a "region-specific, soil-specific, and differentiated straw-return" technical system that enhances resource-use efficiency, soil health, and carbon-sequestration capacity simultaneously.

Sun Yue, a former master's student at IARRP, is the first author of the paper, and Researcher Duan Yinghua is the corresponding author. The study was supported by the State Key Laboratory of Efficient Utilization of Arable Land in China, the National Key R&D Program, and the CAAS Agricultural Science and Technology Innovation Program.