Biochar and smarter water table management could help cut greenhouse gas emissions from peatlands

Peatlands store vast amounts of carbon, but when they are drained for agriculture, they can become major sources of greenhouse gases. Restoring water levels can slow carbon dioxide emissions, yet overly wet peat can produce methane, a powerful greenhouse gas. This creates a difficult climate dilemma: how can peatlands be managed to protect soil carbon without triggering high methane release?

A new two-year study published in Biochar suggests a promising answer. Researchers found that moderate water table management combined with biochar amendment can substantially reduce greenhouse gas emissions from lowland peat soils, while helping maintain peat carbon stores.

The study, led by Peduruhewa H. Jeewani and colleagues, used outdoor mesocosms containing intact peat soil cores from an intensively managed lowland fen peatland in Doncaster, United Kingdom. The team tested how different water table depths and organic amendments affected emissions of carbon dioxide, methane, and nitrous oxide over 730 days. Amendments included Miscanthus biochar, Miscanthus chips, paper waste, biosolids, and cereal straw.

“Peatland management is often seen as a tradeoff between carbon dioxide and methane,” said lead author Dr. Peduruhewa H. Jeewani. “Our results show that this tradeoff can be managed more intelligently. By keeping the water table at a moderate depth and adding a stable material such as biochar, we can reduce overall greenhouse gas losses while protecting peat carbon.”

In the experiment, saturated peat with the water table at the soil surface produced high methane emissions. When the water table was lowered to 20 cm below the surface, methane emissions dropped by more than 90% compared with saturated conditions. Although carbon dioxide emissions increased under moderate drainage, the sharp reduction in methane meant that total greenhouse gas emissions, expressed as CO2 equivalents, were 27 to 35% lower under the 20 cm water table regime.

The most consistent mitigation effect came from biochar. Across the full two-year study, biochar reduced cumulative carbon dioxide emissions by up to 52%, outperforming the other organic amendments. Biochar-treated peat also showed the lowest soil carbon loss among the treatments, suggesting that its stability and redox-buffering properties may help slow peat decomposition.

In contrast, more labile materials with lower carbon-to-nitrogen ratios, such as cereal straw and biosolids, increased carbon dioxide and nitrous oxide emissions under moderately drained conditions. These materials may stimulate microbial activity once oxygen becomes available, accelerating carbon loss rather than preventing it.

“Our findings highlight that not all organic amendments behave the same way in peat soils,” said co-author Professor David R. Chadwick. “Stable amendments such as biochar can support climate-smart peatland management, whereas more easily decomposed materials may unintentionally increase emissions.”

The authors emphasize that peatland restoration and agricultural management should not rely on water level alone. Instead, combining moderate water table control with recalcitrant carbon amendments such as biochar may offer a practical strategy for reducing emissions from cultivated peatlands.

The study provides new evidence that biochar can help address the peatland greenhouse gas dilemma by suppressing carbon losses under contrasting hydrological conditions. As countries seek nature-based strategies to meet climate targets, the findings point to a more nuanced approach for managing peatlands that balances methane control, carbon storage, and agricultural use.

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Journal Reference: Jeewani, P.H., Rhymes, J.M., Evans, C.D. et al. Biochar mitigates the peatland GHG dilemma under contrasting water table regimes: phase-dependent responses of CO₂ and CH₄ over a two-year study. Biochar 8, 93 (2026).   

https://doi.org/10.1007/s42773-026-00610-2   

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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. 

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