Researchers from the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, led by Professor Li Hu, have reported new findings on the regulation of soil organic carbon sequestration. The study shows that precise optimization of carbon and nitrogen input combinations can alleviate the trade-off between soil organic carbon accumulation and stability, thereby supporting sustainable carbon sequestration in cropland soils. The findings were published in Geoderma.

Straw return is an important practice for enhancing soil carbon sequestration in croplands. However, the additional soil organic carbon derived from straw inputs often consists largely of relatively labile and less stable fractions, which may create a trade-off between carbon accumulation and carbon stability. How to optimize this process through nutrient management has therefore become a key focus in soil carbon research. To address this issue, the research team synthesized data from from published studies worldwide, and combined meta-analysis, machine learning, and optimization algorithms to systematically examine the effects of straw return and nitrogen on total soil organic carbon and its different fractions. On this basis, they developed a multi-objective optimization framework that balances carbon sequestration, carbon stability, and resource efficiency.

The results showed that under high straw-return conditions, a moderate increase in nitrogen fertilizer input not only promoted soil organic carbon accumulation but also enhanced the stabilization of carbon fractions. In contrast, under low straw-return conditions, increasing nitrogen input had limited or even inhibitory effects on soil carbon sequestration and stabilization.

Further optimization analysis indicated the national average optimal combination was 271.33 kg N ha^-1 yr^-1 and 9,466.33 kg ha^-1 of straw return. Under these conditions, soil organic carbon content could be increased while improving the distribution of carbon fractions and limiting the relative contribution of unstable components, thereby achieving a synergistic improvement in both carbon sequestration capacity and stability. Compared with conventional management practices, this optimized strategy not only enhanced carbon sequestration but also favored long-term and sustainable soil carbon storage.

This study moves beyond traditional single-factor regulation approaches and proposes a data-driven optimization framework for the coordinated enhancement of soil carbon sequestration and stability. It provides a scientific basis for precision fertilization and efficient utilization of straw resources, and holds significant implications for promoting green and low-carbon agricultural development.

The research was supported by State Key Laboratory of Efficient Utilization of Arable Land in China and the Innovation Program of Chinese Academy of Agricultural Sciences.

Original article link：https://www.sciencedirect.com/science/article/pii/S0016706126000728