Biochar and rewetting combine to curb farm emissions without yield loss
The study, published in Biochar (2025), examined how adjusting the water table and applying biochar - a carbon-rich material produced from plant biomass - influence emissions of carbon dioxide, methane, and nitrous oxide from peat-based agricultural systems. While drained peatlands are prized for their fertility, they are also major emitters of greenhouse gases due to the oxidation of stored carbon.
Led by Dr. Peduruhewa H. Jeewani, the team found that rewetting peat soils by raising the water table cut carbon dioxide emissions by 18 percent and nitrous oxide by 40 percent, though it caused a slight uptick in methane. When biochar was added under these wetter conditions, the combined strategy reduced overall greenhouse gas emissions by as much as 4.64 tonnes of CO2 equivalents per hectare each year, while simultaneously enhancing yields.
Lettuce grown in biochar-treated peat produced between 38 and 56 percent more biomass compared with untreated controls, regardless of moisture level. The researchers also observed that biochar stabilized soil carbon and reshaped the soil's microbial community, lowering the presence of peat-degrading fungi such as Ascomycota and encouraging a broader array of beneficial microbes that boost nutrient cycling and plant growth.
"Our results show that climate-smart soil management can break the trade-off between food production and carbon conservation," said Dr. Jeewani. "By combining biochar with water-level control, farmers can grow profitable crops while restoring soil carbon and cutting emissions."
Globally, agricultural peatlands account for roughly 4 gigatonnes of CO2 equivalents per year. The findings indicate that coordinated measures - pairing rewetting with carbon-based soil amendments - can help protect these valuable ecosystems while supporting Europe's push toward climate neutrality.
Research Report:Wetter farming: raising water table and biochar for reduced GHG emissions while maintaining crop productivity in agricultural peatlands
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