Biochar “switches on” natural oxygen chemistry to suppress soil-borne pathogens and reshape healthier microbial communities
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Biochar modulates soil microbial communities via reactive oxygen species derived from its constituents
view moreCredit: Meng Liu, Siqi Shen, Haiyang Qiao, Huiqiang Yang, Yaru Zhu, Yawei Zhou & Hanzhong Jia
A new study published in Biochar reveals how specially prepared biochar can directly suppress a destructive soil-borne pathogen while helping rebuild a richer and more stable soil bacterial community. The findings offer a clearer scientific basis for designing biochar amendments that protect crops without broadly damaging beneficial soil life.
Soil-borne diseases remain one of agriculture’s most stubborn challenges. Pathogens such as Ralstonia solanacearum, the bacterium responsible for bacterial wilt in crops including tomato and tobacco, can persist in soil and attack plant roots. Traditional soil disinfection methods can reduce pathogens, but they often act broadly, harming both harmful and beneficial microorganisms. This makes it difficult to maintain long-term soil health.
In the new study, researchers led by Hanzhong Jia investigated whether biochar could provide a more targeted way to manage soil pathogens. The team prepared biochars from four types of straw materials at different pyrolysis temperatures, ranging from 300 to 700 °C, and tested their antibacterial effects against R. solanacearum.
The strongest results came from tobacco stem biochar, which showed powerful antibacterial activity. Biochar made at 300 to 400 °C inhibited the pathogen by 92.91% to 99.60%, while biochar produced at 500 to 700 °C achieved 100% inhibition in laboratory tests.
“Our results show that biochar is not only a passive soil amendment,” said Hanzhong Jia, corresponding author of the study. “By controlling the raw material and pyrolysis temperature, we can tune the reactive chemistry of biochar and use it to suppress pathogens while supporting a healthier microbial community.”
The key lies in reactive oxygen species, or ROS. These oxygen-containing molecules can damage bacterial cells through oxidative stress. The study found that biochar’s ROS profile changed with pyrolysis temperature. At lower temperatures, tobacco stem biochar mainly produced free radical ROS, including hydroxyl radicals and superoxide radicals. At higher temperatures, it mainly contained non-radical ROS, including singlet oxygen and hydrogen peroxide.
This temperature-dependent switch mattered. Quenching experiments, which used chemical scavengers to neutralize different ROS, confirmed that ROS were the principal antibacterial mechanism. When the researchers reduced ROS activity, the biochar’s ability to suppress the pathogen also dropped sharply.
The team then tested whether this effect could protect plants. In hydroponic tomato seedling experiments, plants infected with R. solanacearum showed severe wilting. By contrast, seedlings treated with tobacco stem biochar showed no disease symptoms and maintained growth comparable to healthy controls. When ROS were quenched, the protective effect was largely lost, further confirming the central role of ROS.
Beyond pathogen control, the study found that tobacco stem biochar helped reshape the rhizosphere microbiome. In artificial soil and diseased soil systems, biochar increased bacterial richness and promoted a more complex and stable microbial network. The Chao1 richness index increased by 497.77 to 951.34, while microbial network nodes increased by 82 to 136 and edges increased by 1,224 to 2,185. Beneficial genera such as Rhizobium, Paracoccus, Cellvibrio, Fluviicola, and Pseudomonas became more abundant, while several pathogen-associated or less desirable groups declined.
“These findings help explain why biochar can sometimes improve disease resistance in soil,” Jia said. “The benefit comes not only from changing soil properties, but also from direct ROS-mediated interactions with microorganisms.”
The study provides a practical message for agriculture: biochar performance depends strongly on how it is made. By selecting suitable biomass and pyrolysis temperatures, researchers and growers may be able to design biochar products that reduce soil-borne disease pressure while encouraging beneficial microbial recovery.
The research points toward more precise, microbiome-friendly strategies for sustainable crop protection.
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Journal Reference: Liu, M., Shen, S., Qiao, H. et al. Biochar modulates soil microbial communities via reactive oxygen species derived from its constituents. Biochar 8, 122 (2026).
https://doi.org/10.1007/s42773-026-00637-5
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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.
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Journal
Biochar
Method of Research
Experimental study
Article Title
Biochar modulates soil microbial communities via reactive oxygen species derived from its constituents
Biochar and smarter water management could help make rice safer in polluted soils
Biochar Editorial Office, Shenyang Agricultural University
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Synergistic effects of Fe–Mn modified biochar and water management on remediation of Cd and Hg co-contaminated soils
view moreCredit: Tong Sun, Wenhao Yang, Yuebing Sun, Lin Wang & Xuefeng Liang
A new study suggests that pairing iron and manganese modified biochar with carefully chosen irrigation strategies can reduce cadmium and mercury buildup in rice, offering a practical path toward safer food production in co-contaminated paddy fields.
Cadmium and mercury are among the most concerning pollutants in agricultural soils. Both can enter rice plants and accumulate in grains, creating potential risks for people who rely on rice as a daily staple. The challenge is especially difficult because the two metals behave differently in paddy fields. Flooding can help reduce cadmium uptake, but it may increase the formation of methylmercury, a highly toxic form of mercury. Aerobic irrigation can lower mercury accumulation, but it may increase cadmium uptake.
In a study published in Biochar, researchers tested whether iron and manganese oxide modified biochar, known as FMBC, could help solve this tradeoff. The team combined FMBC with two water management regimes, continuous flooding and continuous aerobic irrigation, in pot experiments using cadmium and mercury co-contaminated paddy soil.
“Rice farmers and soil managers often face a difficult choice: water conditions that reduce one metal may worsen the other,” said corresponding author Yuebing Sun. “Our study shows that engineered biochar can help break this conflict by stabilizing both cadmium and mercury while also reshaping the microbial processes that control methylmercury formation.”
The results showed a clear “see-saw” effect of water management. Continuous flooding reduced cadmium bioavailability and promoted iron and manganese plaques on rice roots, which acted as a barrier to cadmium uptake. Under flooding combined with FMBC, the cadmium concentration in rice grains fell to 0.05 mg kg⁻¹, well below China’s food safety limit of 0.2 mg kg⁻¹.
However, flooding alone also encouraged the growth of hgcA-containing mercury-methylating microorganisms, which can convert mercury into methylmercury. In contrast, aerobic irrigation reduced total mercury and methylmercury in rice grains, but increased cadmium uptake.
FMBC helped address both sides of the problem. Under aerobic irrigation, FMBC produced the lowest mercury-related risks, with grain total mercury reaching 0.02 mg kg⁻¹ and methylmercury reaching 6.89 μg kg⁻¹. At the same time, it restricted the cadmium increase usually associated with aerobic conditions.
The study found that FMBC worked through multiple mechanisms. Its surface functional groups and iron and manganese oxides helped bind metals in less available forms. It also promoted root plaque formation, strengthened the plant’s natural barrier against cadmium, and reduced the relative abundance of mercury-methylating microorganisms.
Health risk assessment further supported the benefits of the combined approach. Flooding plus FMBC sharply reduced cadmium-related dietary risk, while aerobic irrigation plus FMBC achieved the lowest hazard quotients for total mercury and methylmercury.
The authors note that the best management choice may depend on the dominant contaminant risk. For cadmium control, continuous flooding with FMBC was most effective. For mercury and methylmercury control, aerobic irrigation with FMBC performed best. Together, these findings point to a flexible strategy for paddy fields where both metals are present.
“This is not simply adding biochar to soil,” Sun said. “It is about matching an engineered amendment with the right water regime so that soil chemistry, root barriers, and microbial communities work together to protect rice quality.”
The researchers suggest that future field studies are needed to confirm long-term performance under real farming conditions, but the findings provide a promising foundation for safer rice production in contaminated regions.
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Journal Reference: Sun, T., Yang, W., Sun, Y. et al. Synergistic effects of Fe–Mn modified biochar and water management on remediation of Cd and Hg co-contaminated soils. Biochar 8, 121 (2026).
https://doi.org/10.1007/s42773-026-00616-w
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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.
Follow us on Facebook, X, and Bluesky.
Journal
Biochar
Method of Research
Experimental study
Article Title
Synergistic effects of Fe–Mn modified biochar and water management on remediation of Cd and Hg co-contaminated soils
Public invited to online Forum on Biochar Research exploring 30 years of progress in soil, crops and climate solutions
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Review and synthesis of 30 years of biochar research and development
view moreCredit: Stephen Joseph
A new online Forum on Biochar Research will bring together global expertise to explain how three decades of biochar science are reshaping understanding of soil health, crop productivity and climate action. The event, titled “Review and synthesis of 30 years of biochar research and development,” will be delivered by Prof. Stephen Joseph of The University of New South Wales, Australia, and hosted by Prof. Jianying Shang of China Agricultural University.
The forum will take place on July 14, 2026, at 8:00 AM BST in London, 3:00 PM CST in Beijing, 9:00 AM CEST in Central Europe, and 10:00 AM EEST in Eastern Europe. The public may join via Zoom Meeting ID: 615 672 5359, Passcode: 123456.
Biochar, a carbon-rich material made by heating biomass under limited oxygen, has attracted growing attention as a tool for improving soils while storing carbon. The lecture will synthesize evidence from 30 years of research on how biochar interacts with soil and plants, from early dissolution over the first weeks, to surface development over several months, to long-term aging in soil aggregates.
“Biochar is not a single product with one fixed effect. Its benefits depend on how it is made, where it is used and which soil constraints it is designed to address,” Prof. Joseph said. “When used wisely, biochar can support more resilient agriculture, long-term carbon storage and a circular bioeconomy.”
According to the review, biochar can increase phosphorus availability, reduce plant uptake of heavy metals, build soil organic carbon, lower non-CO2 greenhouse gas emissions and improve crop yields, especially in acidic, nutrient-poor or sandy dryland soils.
The forum will offer researchers, students, farmers, policymakers and environmental professionals a clear overview of where biochar science has been, what it has learned and how tailored biochar applications may support food security and climate mitigation.
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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.
Follow us on Facebook, X, and Bluesky.
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About Carbon Research
The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.
