As the planet warms, soils may release more nitrous oxide, a powerful greenhouse gas linked to agriculture, fertilizer use, and microbial nitrogen cycling. A new study published in Biochar shows that biochar, a carbon-rich material made by heating biomass with limited oxygen, can change how strongly soil nitrous oxide emissions respond to rising temperatures. But the effect is not one-size-fits-all.
Researchers tested two contrasting soils, agricultural soil and forest soil, with two types of biochar made from wood and rice husk. They applied the biochars at two rates, 1% and 3%, and incubated the soils at 10 °C, 20 °C, and 30 °C. The team focused on Q10, a measure of how much a biological process changes when temperature rises by 10 °C.
The study found that nitrous oxide emissions increased with warming in both soils, but forest soil was more temperature-sensitive than agricultural soil. Q10 values were higher in forest soil, ranging from 1.63 to 2.84, compared with 1.13 to 1.63 in agricultural soil. This suggests that warming may have a stronger effect on nitrous oxide release in soils with more active nitrogen cycling and higher nutrient availability.
"Biochar is often discussed as a climate mitigation tool, but our findings show that its effects depend strongly on the soil environment," said corresponding author Xiaolin Liao. "The same biochar treatment can push soil nitrogen processes in different directions depending on whether the soil is agricultural or forest soil."
Among all treatments, only high-rate wood biochar significantly changed the temperature sensitivity of nitrous oxide emissions. In agricultural soil, it lowered Q10, meaning that nitrous oxide emissions became less responsive to warming. The researchers found that this treatment strongly reduced nitrate availability and weakened the temperature response of nitrate, creating greater substrate limitation for nitrous oxide production.
In forest soil, however, high-rate wood biochar had the opposite effect. It increased Q10, even though biochar generally reduced total nitrous oxide emissions in that soil. The authors suggest that wood biochar may have altered short-term nitrate retention and strengthened the coupling between nitrification and nitrate-consuming processes, making nitrous oxide emissions more sensitive to temperature changes.
"This result is important because it shows that reducing total emissions and reducing warming sensitivity are not always the same goal," said first author Siyu Luo. "A treatment may suppress nitrous oxide emissions overall, while still changing how emissions respond to future warming."
The team also measured soil pH, dissolved organic carbon, ammonium, nitrate, microbial biomass carbon, and several nitrogen-related microbial functional genes. Their path modeling showed that temperature was the dominant driver of nitrous oxide emissions, acting through changes in substrate availability, soil pH, and microbial genes. Biochar acted as a secondary modulator, shaping the soil conditions that control microbial nitrogen transformations.
The findings add nuance to the growing interest in biochar as a climate-smart soil amendment. Rather than applying biochar with a universal expectation of greenhouse gas mitigation, the study suggests that soil type, biochar feedstock, and application rate should all be considered when designing biochar strategies under climate change.
"Our study highlights the need for soil-specific biochar management," Liao said. "To use biochar effectively for nitrous oxide mitigation, we need to understand not only whether it lowers emissions, but also how it changes the sensitivity of those emissions to warming."
The research provides new mechanistic insight into how biochar, temperature, and microbial nitrogen cycling interact, offering guidance for more targeted soil management in a warming world.
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Journal Reference: Luo, S., Li, Z., Hu, J. et al. Biochar modulates temperature sensitivity of soil N2O emissions: soil-specific mechanisms. Biochar 8, 81 (2026).
https://doi.org/10.1007/s42773-026-00591-2
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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.
