Pursuing implementation solutions for targeted nitrogen management in agriculture- a novel approach to synthesize knowledge and facilitate sustainable decision making based on collaborative landscape modelling.

Regulation of nitrate emission from agriculture to aquatic environments in Denmark currently depend on general rules for nutrient application and associated farm-level reporting schemes. Similar or comparable centralized regulation instruments dedicated to controlling and limiting rather than focusing and improving N application practices exist in large parts of the OECD. Recent policy debates have exposed an array of problems relating to this type of regulation. Problems include issues of appropriate scale, transparency and failures to adapt intervention and regulation to relevant geo-ecological variations in contexts where general rules are being imposed on varied agro-ecosystems. Therefore it has been proposed to rescale regulation to better fit relevant socio-political and agro-environmental processes including the scale of farmers' decision making, the scale of relevant hydrological systems and the scale of key agro-ecological conditions such as soil characteristics and drainage. However, the challenge of shifting the regulation to a more local scale raises a number of questions. These include (1) How information produced locally can be integrated with national scale data? (2) In what way integrated datasets can used to model environmental effects of current and possible land use patterns? (3) In what way data and estimates of consequences of land use changes are best made available in decision making processes? To address these questions this article reports on ongoing work in Denmark to develop a decision support tool for N-management at the scale of agricultural landscapes, which are areas where a similar pattern of land use is repeated across the land surface, reflecting a specific mode of adapting agriculture to natural conditions. The aim of the article is to evaluate the design of a decision support tool aiming at enabling strategic N-management at landscape scales by linking decision support at the scale of individual farms with decision support targeted at groups of farms where a coordinated effort to solve common problems may be more efficient. Design targets for the tool were established empirically based on evidence from exploratory workshops with farmers and other stakeholders in 6 case areas across Denmark. On this basis a prototype GIS-tool for capturing, storing, editing, displaying and modelling landscape scale farming practices and associated emission consequences was developed. The tool was designed to integrate locally held knowledge with national scale datasets in live scenario situations through the implementation of a flexible, uniform and editable data model for land use data - the dNmark landscape model. Based on input data that is corrected and co-authored by workshop participants, the tool estimates the effect of potential land use scenarios on nutrient emissions. The tool was tested in 5 scenario workshops in case areas in Denmark in 2016, on the basis of which its design is evaluated and discussed in this article.

Abating N in Nordic agriculture - Policy, measures and way forward.

During the past twenty years, the Nordic countries (Denmark, Sweden, Finland and Norway) have introduced a range of measures to reduce losses of nitrogen (N) to air and to aquatic environment by leaching and runoff. However, the agricultural sector is still an important N source to the environment, and projections indicate relatively small emission reductions in the coming years. The four Nordic countries have different priorities and strategies regarding agricultural N flows and mitigation measures, and therefore they are facing different challenges and barriers. In Norway farm subsidies are used to encourage measures, but these are mainly focused on phosphorus (P). In contrast, Denmark targets N and uses control regulations to reduce losses. In Sweden and Finland, both voluntary actions combined with subsidies help to mitigate both N and P. The aim of this study was to compare the present situation pertaining to agricultural N in the Nordic countries as well as to provide recommendations for policy instruments to achieve cost effective abatement of reactive N from agriculture in the Nordic countries, and to provide guidance to other countries. To further reduce N losses from agriculture, the four countries will have to continue to take different routes. In particular, some countries will need new actions if 2020 and 2030 National Emissions Ceilings Directive (NECD) targets are to be met. Many options are possible, including voluntary action, regulation, taxation and subsidies, but the difficulty is finding the right balance between these policy options for each country. The governments in the Nordic countries should put more attention to the NECD and consult with relevant stakeholders, researchers and farmer's associations on which measures to prioritize to achieve these goals on time. It is important to pick remaining low hanging fruits through use of the most cost effective mitigation measures. We suggest that N application rate and its timing should be in accordance with the crop need and carrying capacity of environmental recipients. Also, the choice of application technology can further reduce the risk of N losses into air and waters. This may require more region-specific solutions and knowledge-based support with tailored information in combination with further targeted subsidies or regulations.