Agricultural landscapes are battle fields for meeting opposing needs, from food production to a growing number of people to reducing negative environmental effects on water and air. To achieve the environmental goals of improved water quality and Ingen övergödning, a number of agri-environmental measures have been suggested as effective tools to reduce soil erosion and nutrient losses. However, they can lead to pollution swapping and increased emissions of a greenhouse gas N2O through incomplete denitrification. This can happen in mitigation measures that reduce water flow and erosion e.g. sedimentation ponds, constructed wetlands and two-stage ditches. Longer residence time and high agricultural load of nitrate nitrogen can enhance denitrification in bed sediments of these measures and production of harmless dinitrogen gas N2. However, if the carbon pool is limited, denitrification can be incomplete, which will lead to emissions of harmful nitrous oxide gas N2O. This project will measure the denitrification rates and N2O emissions from a number of mitigation measures in Sweden, to see if by trying to reduce eutrophication we don't contribute to climate warming.