Scientists say adding biochar to lowland peat soils could ensure wet farming, known as paludiculture, is financially viable for farmers, which would help mitigate climate change.
A new project led by the UK Centre for Ecology & Hydrology (UKCEH), funded by a £500,000 grant from Natural England, will identify cost-effective methods of applying biochar under paludiculture conditions.
Biochar is a charcoal-like substance produced when biomass, such as agricultural waste or forestry residue, decomposes after being heated up at very high temperatures without oxygen. Biochar has a high carbon content and is largely resistant to decomposition, making it an ideal tool for long-term carbon storage.
Peat soils, which are huge carbon stores, are drying out following centuries of drainage for agriculture, which is causing its organic matter to decompose and release carbon into the atmosphere. In 2021, cropland on peat was estimated to emit the net equivalent of around 5.6 million tonnes of carbon dioxide (CO2), which is over 1% of UK greenhouse gas emissions from all sources.
Although paludiculture offers a solution to reduce emissions from cultivated peat, the type of crops that can be grown on wet soils are not as profitable as the typical crops grown on highly productive drained farming systems. Therefore, many farmers are unable or reluctant to adopt wet farming.
If cost-effective ways of applying biochar to soils can be established and ongoing UK trials can quantify the carbon storage potential from biochar, then this would enable farmers to gain an additional source of income from carbon financing. This would involve the sale of the carbon benefits from these practices as credits to companies who wish to offset their CO2 emissions.
Dr Jenny Rhymes, a UKCEH greenhouse gas flux scientist who is leading the new research, says: “There is a range of produce that can be grown in waterlogged soils, including celery for food, reeds for thatching and willow for bioenergy. However, because wet farming is by nature less productive it is likely to be less profitable than growing high-value food crops.
“If biochar can be integrated with paludiculture, carbon finance revenues for farmers can be improved and therefore more attractive to adopt. Our project aims to identify biochar management practices, specific to paludiculture, that maximise the ability of lowland peat soils to remove and store carbon.
“The work will build on national trials by partners who are growing crops in waterlogged soils to trial biochar integration.”
The new UKCEH biochar project is being funded as part of a large-scale investment in peatland restoration announced by the UK Government. Some 12 projects are being funded by Natural England’s £5 million Paludiculture Exploration Fund to support the reduction of barriers to developing commercially viable wet farming on lowland peat soils.
There is also £7.5 million of new Government funding for innovative water management projects at lowland peat sites to help mitigate the impacts of climate change.
Meanwhile, Robert Caudwell, chair of an independent task force appointed by the UK Government, has published a report making 14 recommendations including new investment in wet farming on peat soils, and in water storage, management and control, as well as the creation of viable private financing initiatives. The Lowland Agricultural Peat Task Force comprised a range of experts including Professor Chris Evans, a biogeochemist at UKCEH.