Land management effects on ditch greenhouse gas dynamics in UK lowland peatlands

The UK’s lowland peatlands occupy ~465,000 ha and are distributed across much of the country. The large majority (90%) of this lowland peat has been drained for agriculture, creating productive, fertile soils, but also exposing previously waterlogged organic matter to decomposition. Peatland drainage can alter aquatic biogeochemistry by increasing dissolved organic carbon fluxes to surface waters and promoting greenhouse gas (GHG) emissions from drainage ditches. Peatland rewetting has been demonstrated as an efficient mitigation technique for peatland GHG emissions. It is critical to understand how peatland drainage and subsequent rewetting may influence GHG emissions, as drainage may have allowed long-term accumulation of substances of agricultural or industrial origins, such as macronutrients (e.g. carbon, nitrogen, phosphorous) and heavy metals, which are released upon rewetting. Here, we present the results of an on-going, national-scale field study (part of the LowlandPeat3 project, https://lowlandpeat.ceh.ac.uk/lowlandpeat3) examining the spatio-temporal dynamics of GHG emissions in ditches draining arable lands (including conventional and regenerative agriculture) at paired “business as usual” and rewetted sites, during the baseline period prior to rewetting. We have measured carbon dioxide, methane, and nitrous oxide concentrations (and modelled fluxes) approximately monthly from sites across England. The results of this research will help us understand the risks and benefits of peatland rewetting on water quality, drinking water, aquatic ecology, and climate, to help inform lowland peat management and policy.