Mitigating diffuse nitrogen losses in the Nordic-Baltic countries

• We describe the history of mitigating diffuse nitrogen losses in the Nordic-Baltic countries.
• We provide an overview of types of mitigation measures and the extent to which they are used in the Nordic-Baltic countries.
• We examine whether efforts to mitigate diffuse nitrogen losses are reflected in field nitrogen balances.
• We examine the effect of mitigating measures on diffuse nitrogen losses as measured in national monitoring programmes.

Concerns over deteriorating water quality in both freshwater and marine waters have initiated efforts to control diffuse nitrogen (N) losses in all Nordic-Baltic countries. The national strategies for combating diffuse nitrogen losses including selection of mitigation measures, areal extent of measures and incentives for farmers to use the measures differ between the Nordic-Baltic countries. Effects of legislation and other incentives to change agricultural practices and hence to reduce N losses from agriculture are first observed by monitoring close to the source of these losses. Consequently, all Nordic-Baltic countries have set up monitoring programmes including small agriculturally dominated catchments where inputs, outputs and loss of N are followed closely at plot, field and/or catchment scale. We explore the connection between political decisions and regulations, provide an overview of measures and incentives used in the Nordic-Baltic countries, and assess the effect of the measures based on data from national monitoring programmes.