New study shows alkaline biochar boosts soil health in saline environments
image: Microbial nutrient limitation and carbon use efficiency in saline-alkali soil amended with biochar: insights from ecoenzymatic C:N:P stoichiometry
Credit: Guorui Zhang, Lan Zhang, Ziyue Shi, Yunfeng Yang & Jie Liu
A new study published in Biochar reveals that alkaline biochar, a type of carbon-rich soil amendment, significantly improves microbial carbon use efficiency and nutrient cycling in saline-alkali soils. These findings could help farmers and land managers restore degraded soils in arid and semi-arid regions around the world.
Saline soils, which cover more than 800 million hectares globally, present major challenges for agriculture due to high salt levels and poor nutrient availability. The study, led by Guorui Zhang and colleagues at Lanzhou University, tested two types of biochar—alkaline and acid-modified—in saline-alkali soils planted with Medicago sativa, a salt-tolerant legume. The researchers found that alkaline biochar, applied at moderate rates, enhanced microbial carbon use efficiency, reduced microbial carbon limitation, and shifted nutrient metabolism from nitrogen to phosphorus limitation. In contrast, acid-modified biochar did not provide the same benefits.
“Alkaline biochar helps microbes in saline soils use carbon more efficiently, which means more carbon is stored in the soil rather than lost to the atmosphere,” said Dr. Guorui Zhang, lead author of the study. “This could be a game-changer for sustainable agriculture in salt-affected areas.”
The study also showed that alkaline biochar increased the activity of enzymes that help plants access phosphorus, a crucial nutrient often lacking in saline soils. Both types of biochar reduced soil salinity and pH, but only alkaline biochar led to clear improvements in microbial nutrient cycling and plant growth.
These results highlight the importance of choosing the right type of biochar for soil restoration. “Our findings suggest that not all biochars are equal—alkaline biochar outperforms acid-modified biochar in saline environments,” said Zhang. “This could help guide better soil management strategies for farmers dealing with salt stress.”
The research was supported by the National Natural Science Foundation of China and other institutions. The authors hope their work will inform future soil restoration projects and contribute to global efforts to combat land degradation and climate change.
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Journal Reference: Zhang, G., Zhang, L., Shi, Z. et al. Microbial nutrient limitation and carbon use efficiency in saline-alkali soil amended with biochar: insights from ecoenzymatic C:N:P stoichiometry. Biochar 7, 68 (2025).
https://doi.org/10.1007/s42773-025-00458-y
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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.