Soil acidification is a growing threat to food production, especially in intensively managed agricultural regions where repeated fertilizer use can gradually make soils more acidic, reduce nutrient availability, and increase the mobility of toxic metals. A new five-year field study published in Biochar shows that biochar may do more than simply neutralize acidic soils. It can help organize a coordinated recovery process across the entire soil ecosystem.
The study, titled "Biochar orchestrates coordinated soil-microbe-metabolite responses in acidifying paddy soils: evidence from a 5-year field study," compared biochar with two commonly used soil amendments, lime and swine manure, in an acidic paddy field in Zhejiang Province, China. The research team applied biochar at three rates, along with lime and manure treatments, and then used advanced multi-omics tools to examine changes in soil chemistry, microbial communities, viral communities, gene functions, and soil metabolites.
"Our findings show that biochar does not act only as a chemical amendment," said corresponding author Huaihai Chen. "It appears to initiate a step-by-step ecological cascade, beginning with improved soil conditions and extending to microbial functions and metabolite production that are important for long-term soil health."
Across treatments, soil amendments helped reduce acidification, with soil pH increasing from about 5.5 to 6.4 and exchangeable aluminum dropping sharply from 12.5 to 3.5 mg kg−1. However, the strongest and most coordinated responses occurred under high-dose biochar treatment. Compared with lime and manure, biochar produced broader changes that linked improved soil chemistry with biological and metabolic recovery.
The researchers found that high-dose biochar improved soil organic matter, cation exchange capacity, and nutrient availability while reducing the bioavailability of metals such as aluminum, cadmium, iron, and nickel. These chemical improvements were associated with shifts in prokaryotic and viral communities. Biochar enriched microbial groups such as Chloroflexi and Planctomycetota, which are often linked with nutrient cycling, and also influenced viral groups including Algavirales and Crassvirales.
These community changes were accompanied by shifts in microbial functional genes. In particular, high-dose biochar increased genes related to membrane transport, nutrient exchange, cell-to-cell interactions, ABC transporters, and quorum sensing, suggesting a more connected and active soil microbial network. At the same time, biochar altered carbohydrate-active enzyme profiles and reduced certain genes associated with glycoside hydrolases, which may be linked to changes in carbon processing and organic matter stabilization.
Soil metabolites also changed under biochar amendment. The study found enrichment of lipids, lipid-like molecules, and terpenoids, compounds that may support plant growth, microbial activity, and long-term carbon stabilization. These metabolite shifts were less apparent under lime or manure, indicating that biochar's long-term effect may depend on its ability to connect soil chemistry with biological function.
Importantly, lime and manure improved some soil properties but did not generate the same integrated response. Lime mainly acted through pH adjustment, while manure had more limited effects on acid neutralization and carried potential concerns related to metals and pathogens. In contrast, biochar's porous structure, alkalinity, nutrient content, and environmental persistence may allow it to support long-lasting soil restoration.
"The long-term advantage of biochar lies in its ability to coordinate soil, microbes, viruses, genes, and metabolites as one system," said co-corresponding author Jiaxin Li. "This provides a mechanistic basis for using biochar as an ecosystem restoration tool in acidifying agricultural soils."
The findings suggest that properly managed biochar application could help farmers and land managers improve acidic paddy soils while supporting nutrient cycling, reducing metal risks, and strengthening soil ecological resilience.
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Journal Reference: Meng, J., Cui, Z., Li, Z. et al. Biochar orchestrates coordinated soil-microbe-metabolite responses in acidifying paddy soils: evidence from a 5-year field study. Biochar 8, 83 (2026).
https://doi.org/10.1007/s42773-026-00598-9
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About Biochar
Biochar (e-ISSN: 2524-7867) is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
