Biochar–starch combo helps lettuce fight back against antibiotic pollution

Antibiotic residues in farmland soils are an emerging global concern, with potential risks for ecosystems, food safety, and human health. Now, researchers in China report a promising new approach to tackling one of the most common culprits—oxytetracycline (OTC)—by combining biochar with carbohydrate-based soil amendments. Their study shows that this simple yet effective strategy not only accelerates the degradation of OTC in soil but also reduces its transfer into lettuce, a widely consumed leafy vegetable.

The research, published in Biochar, tested different treatments: biochar alone, biochar plus glucose, biochar plus sucrose, and biochar plus starch. Lettuce was grown under controlled greenhouse conditions in soils spiked with OTC, simulating heavily contaminated agricultural fields.

The team found that biochar alone enhanced OTC breakdown by up to 67% and lowered its movement into lettuce leaves. When paired with carbohydrate carbon sources, the results were even more striking. Glucose and sucrose provided a short-term boost in microbial and enzyme activity, but their effects quickly faded as these sugars were rapidly consumed. In contrast, the biochar–starch treatment (BCST) consistently outperformed the others: OTC degradation reached 92%, the antibiotic’s half-life in soil dropped to just eight days, and microbial biomass carbon increased by 55% over the growing period.

Importantly, the starch-based treatment also reduced OTC accumulation in lettuce roots and leaves, helping safeguard food quality. While overall plant biomass did not differ significantly across treatments, BCST improved nitrogen uptake and chlorophyll content in lettuce, signs of healthier crop growth under antibiotic stress.

“Our findings highlight biochar–starch as a cost-effective and sustainable solution for reducing the risks of antibiotic residues in farmland,” said corresponding author Dr. Qiang Zheng of China Agricultural University. “By supporting soil microbes and maintaining enzyme activity, this strategy promotes long-term antibiotic degradation while protecting crop health.”

Antibiotic contamination of soils—often linked to livestock manure and wastewater irrigation—is widespread, with oxytetracycline frequently detected at concerning levels. Residual antibiotics not only harm soil microorganisms and plant growth but also contribute to the spread of antibiotic resistance genes through the food chain.

The study suggests that pairing biochar with slow-release carbon sources such as starch could be a practical tool for farmers and land managers seeking to mitigate these risks. The approach leverages natural soil processes, avoids reliance on chemical treatments, and could be adapted to a range of crops and soils.

“Antibiotic pollution poses a dual threat to agricultural sustainability and public health,” added co-corresponding author Dr. Peiling Yang. “Our work provides new insight into soil remediation strategies that are both effective and environmentally friendly.”

The authors note that further field trials are needed to confirm large-scale effectiveness under real-world farming conditions. Still, the findings open new possibilities for managing antibiotic residues and ensuring safer food production.

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Citation: Zeng et al. “Enhancing oxytetracycline degradation and reducing its transfer to lettuce using biochar combined with carbohydrate carbon sources.” Biochar (2025). https://doi.org/10.1007/s42773-025-00502-x 

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Media Contact:
Wushuang Li
liwushuang@vip.126.com

About Biochar

Biochar 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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