Over-reliance on chemical fertilizers to feed a growing population has often led to soil degradation and a decline in microbial diversity. Scientists are seeking sustainable alternatives that can maintain crop yields while revitalizing the soil. A new field study from the Chinese Academy of Agricultural Sciences offers a promising solution by demonstrating how biogas slurry—a nutrient-rich liquid byproduct of anaerobic digestion—can significantly enhance soil health and its ability to sequester carbon.
The investigation was conducted over three years at a dryland agriculture research station in China. Researchers compared the effects of applying biogas slurry topdressing (BST) against conventional chemical fertilizer topdressing (CFT) on maize crops. By collecting soil samples at three different depths and three distinct crop growth stages, the team performed a comprehensive analysis of soil chemistry and used 16S rRNA gene sequencing to map the changes in the bacterial communities over time and space.
The results show that using biogas slurry delivers clear and consistent benefits to the soil. Across all soil depths and growth phases, BST treatment increased the total potassium permanganate oxidation carbon (TPOXC) —a measure of active soil carbon—by an average of 13.4%. The overall soil quality index (SQI) also saw a significant average increase of 18.3%, indicating a direct improvement in the soil’s physical, chemical, and biological properties, particularly in the topsoil layer where biological activity is highest.
Beyond improving soil chemistry, biogas slurry fundamentally reorganized the underground microbial ecosystem. The application enriched beneficial, fast-growing bacterial groups, such as the phylum Firmicutes , which are known to break down complex organic matter. Perhaps most importantly, the treatment altered the web of interactions within the soil. While chemical fertilizers fostered a competitive environment between bacteria and soil factors, biogas slurry promoted a cooperative one , creating a more resilient and efficient microbial network that supports nutrient cycling.
The analysis of bacterial functions revealed a significant climate co-benefit. By mapping the genetic potential of the soil microbiome, the scientists found that BST enhances the soil’s capacity for carbon fixation. The treatment boosted the abundance of genes involved in two key biochemical routes for capturing carbon: the Wood-Ljungdahl (WL) and 3-Hydroxypropionate (3-HP) cycle pathways . This suggests that soils treated with biogas slurry are not just healthier and more fertile; they are also more effective at drawing down atmospheric carbon and storing it long-term.
The authors acknowledge that the functional predictions were based on existing genomic databases, which may have limitations. Future work will aim to validate these findings using direct gene quantification and metagenomic techniques. Expanding these long-term studies will be essential for optimizing biogas slurry application as a widespread strategy for sustainable agriculture that can improve food security while contributing to climate change mitigation.
Corresponding Author: Jiandong Wang or Haitao Wang
Original Source: https://doi.org/10.1007/s44246-026-00267-3
Contributions: Xiaoyang Liang and Chuanjuan Wang contributed to investigation, formal analysis and data curation; Xiaoyang Liang drafted the original manuscript and both reviewed and edited the work and developed software. Yongxing Wen, Junjie Qin, Zonglu Yao and Baoqing Chen conducted investigation and reviewed and edited the manuscript. Jiandong Wang handled conceptualization, resources, supervision, project administration and funding acquisition, in addition to conducting investigation and reviewing/editing. Haitao Wang provided resources, supervised the work, administered the project and acquired funding, alongside conducting investigation and reviewing/editing. All authors reviewed and edited the manuscript.
Carbon Research
Experimental study
Not applicable
Resource recycling through biogas slurry topdressing reorganizes spatiotemporal dynamics of soil bacteria and carbon sequestration pathways
4-Jun-2026
The authors declare no competing interests.