Leicester team shows how to reduce carbon emissions from agricultural peatland

Raising the water table could slow down global warming, boost crop yields, and preserve peat soils according to a new study.

A team of scientists from the University of Leicester began measuring the emissions of carbon dioxide (CO₂), a greenhouse gas, on farmed East Anglian peat soil in 2012, and in 2015 combined with researchers from the University of Sheffield to investigate the impact that manipulating the water table would have on these emissions.

Published in Science of the Total Environment, this controlled environment study found that raising the water table closer to ground level in peat soil cores by 20 cm not only reduced soil CO2 emissions, but also improved the growth of radishes. Importantly, the study also showed a decrease in the rate of peat loss from these carbon rich soils that have been significantly diminished both in area and depth since they were drained for agricultural use.

Continuous field measurements have been collected by University of Leicester doctoral student Alex Cumming, of the Department of Geography, with the support of his supervision team Dr Joerg Kaduk, Professors Susan Page and Heiko Balzter.

The international team of researchers from the universities of Leicester, Sheffield, Exeter and San Diego, raised the water table from 50 cm to 30 cm in agricultural peat soil collected from the Norfolk Fens – one of the UK’s largest lowland peatlands under intensive cultivation. The findings, now published in the journal Science of the Total Environment, showed elevating the water table increased the average uptake of CO₂.

The Sheffield study team will now aim to analyse other crops, including celery, and look into the impact of fertiliser use on greenhouse gas emissions and productivity. At Leicester, the focus will be on measuring carbon emissions from a field with raised water table, to see how well the controlled environment results are transferrable to the landscape and identifying opportunities to reduce soil carbon loss at critical phases during the annual farming cycle, e.g. during ploughing, harvesting and the winter fallow period.