Mitigating impacts of agriculture on peatland carbon losses

The project will seek to identify and quantify the potential greenhouse gas (GHG) emissions benefits of a range of possible mitigation options for agriculturally managed lowland peatlands in England and Wales.

The project will comprise:

1. A desk based assessment of the practical and economic potential of high water table ‘paludiculture’ management
2. A review of the societal impacts of drainage-based lowland peat management, for example in relation to infrastructure
3. A field experimental study to quantify the magnitude of emissions reductions that may be achievable by raising water levels within conventional arable systems, together with any potential trade-offs in relation to crop yields, disease risk and soil trafficability
4. An evaluation of the economic, environmental, societal and practical costs, benefits, opportunities and barriers associated with altered hydrological management of agricultural peatlands

For the experimental component of the project, we will work with G’s Fresh, a major agricultural company operating on organic soils. Together, we will establish a field-based, replicated and controlled water table manipulation experiment, using an automated chamber system to measure GHG fluxes at a high temporal resolution over two growing seasons. The experiment will incorporate a business as usual (control), medium, high and alternating (‘winter re-wetting’) water table treatments.

During the experiment, we will also measure key parameters relating to crop health and yield, soil condition and trafficability, and water balance and availability. The experiments will be co-located with a network of established eddy covariance flux tower sites operated by the team. These towers will provide high-frequency, multi-year data on soil carbon balance across a range of land-uses, peat types, drainage depths and crop rotations. We will also carry out more extensive ‘snapshot’ surveys of soil respiration rates across a wider range of site types and management in order to place the experimental study and flux tower data into a broader landscape context.

The ultimate aims of the project will be to provide Defra, other policymakers and the farming community with best-practice advice on a range of approaches to mitigate GHG emissions from agriculturally used peatlands. The work will:

• Support Defra’s 25 year plan to reduce GHG emissions from the agricultural sector
• Help to reduce the societal costs of current deep-drained arable systems on peat, and
• Contribute to extending the economic lifetime of farmed organic soils by reducing rates of long-term subsidence and soil loss.

External co-investigator: Professor Chris Evans, Centre for Ecology and Hydrology, Bangor