Biochar could help make tea farming cleaner, safer, and more climate resilient

Tea is one of the world’s most widely consumed beverages, but the soils that sustain tea plantations are under growing pressure. Long-term fertilizer use, monocropping, soil acidification, nutrient loss, heavy metal contamination, and climate stress are threatening both tea productivity and environmental safety. A new review published in Biochar examines how biochar, a carbon-rich material produced by heating biomass under limited oxygen, could become a practical tool for more sustainable tea cultivation.

“Tea farming depends on healthy soil, but many tea-growing regions are facing serious soil degradation and contamination risks,” said corresponding author Md Shafiqul Islam. “Our review shows that biochar can help address several of these challenges at the same time, from improving soil fertility to reducing the movement of toxic metals into tea leaves.”

Tea plants often grow in acidic, nutrient-poor soils. Intensive management can worsen acidity, wash away essential nutrients, and increase the mobility of toxic metals such as cadmium, lead, and arsenic. These problems can weaken plant growth and raise food safety concerns. The review synthesizes recent field and laboratory studies on the biochar, soil, and tea nexus, focusing on five connected areas: soil properties, microbial communities, nutrient cycling, tea productivity and quality, and heavy metal detoxification.

The authors report that biochar can buffer soil acidity, increase cation exchange capacity, improve soil structure, enhance water retention, and reduce nutrient leaching. These changes create a more favorable root environment for Camellia sinensis, the plant used to produce tea. Biochar can also provide habitat for beneficial microorganisms and shift microbial communities toward groups that support nutrient turnover, carbon cycling, and soil resilience.

Biochar may also improve the efficiency of fertilizer use. By holding ammonium, phosphorus, potassium, calcium, and magnesium in the root zone, biochar can help tea plants access nutrients more effectively while reducing losses to leaching or gas emissions. Some studies reviewed by the authors showed improvements in root development, leaf biomass, shoot density, bud weight, and tea yield when biochar was used alone or with organic and mineral fertilizers.

The review also points to potential benefits for tea quality. Biochar-amended soils can support biochemical pathways linked to free amino acids, flavonoids, soluble sugars, catechins, and other compounds that shape tea flavor, aroma, and sensory balance. However, the authors caution that results depend strongly on biochar feedstock, pyrolysis temperature, soil type, application rate, and local management practices.

One of the most important findings concerns food safety. Biochar can bind metals through surface functional groups and mineral phases, shifting contaminants into less available forms. In contaminated tea soils, this can reduce the uptake and movement of heavy metals into edible tea leaves and buds, lowering potential exposure risks for consumers.

“Biochar should not be treated as a one-size-fits-all amendment,” said co-author Shangwen Xia. “Its performance depends on how it is made, where it is applied, and what problem the grower wants to solve. Matching biochar properties with local soil conditions is essential.”

The review also links biochar use to climate-smart agriculture. Because biochar contains stable carbon that can persist in soil for long periods, it may contribute to carbon sequestration and greenhouse gas mitigation. Some studies also suggest that biochar can reduce nitrous oxide and carbon dioxide emissions from tea soils.

Despite these promising findings, the authors emphasize major research gaps. Long-term field trials remain limited, especially in tropical tea-producing regions. More work is needed to understand cultivar-specific responses, biochar aging, microbial mechanisms, heavy metal stability, and the best application rates for different soils.

The authors conclude that biochar offers a promising pathway toward healthier tea soils, safer tea products, higher nutrient efficiency, and more resilient tea farming systems, but its use must be guided by site-specific science and long-term field evidence.

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Journal Reference: Islam, M.S., Xia, S. Biochar–soil–tea nexus: a review of soil health, microbial interactions, and sustainable Camellia sinensis cultivation. Biochar 8, 71 (2026).   

https://doi.org/10.1007/s42773-026-00580-5   

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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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