Water management and mitigation of greenhouse gas emissions from agricultural lowland peatlands

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NERC : Benjamin Freeman : NE/R010218/1Global peatlands are our largest terrestrial carbon store. Peatlands form under waterlogged conditions but have been widely drained to allow agricultural use. The drained peat provides highly productive agricultural land thanks to its high nutrient content and capacity to store water that is readily available to plant roots. However, drainage of peatlands to enable agricultural production also allows oxygen into the soil and this stimulates microbes which begin to break down the organic material that makes up the peat. This microbial activity results in substantial greenhouse gas (GHG) emissions and the loss of the carbon stored in the peat, contributing to climate change. In both Canada and the UK, lowland peatlands provide highly productive agricultural soils and play a key role in the production of economically important vegetable crops. Consequently there is an inherent trade-off in peatland agriculture between climate, economic and food security concerns, which creates a challenge for policy makers and land managers. This research project sets out to help address two key challenges on the road to responsible peatland management. Firstly we will calculate carbon footprints for crops which include the GHG emissions derived from the breakdown of the peat soil. This will improve our understanding of the trade-offs involved in peatland agriculture and help highlight key opportunities to reduce GHG emissions in the food production process. Secondly, we will use modelling approaches to understand better the practicalities of how intermediate groundwater management might be used to help reduce GHG emissions from agricultural peatlands. Reducing the drainage depth and thus raising the groundwater slightly nearer to the field surface reduces the volume of peat soil that is aerated and reduces microbial activity in layer below the water table. Therefore, this has been proposed as an option to reduce GHG emissions from peat soils, whilst allowing agricultural production to continue. However, if the groundwater and water supply are not managed correctly this could have serious consequences for farmers, as water shortages and surface water flooding can damage crops and livelihoods. Modelling will allow simulation of the effects of different water management scenarios. This will allow identification of both the key challenges to implementation of intermediate groundwater management and opportunities to maximize its effectiveness. Given the importance of developing responsible management strategies for agricultural lowland peatlands, this research will help inform decision makers in policy and industry, benefiting both the UK and Canada, and helping to protect these valuable natural resources.