Denmark

Denmark is situated in the Atlantic lowland region of northern Europe dominated by intensive agriculture. The main land use is agriculture which covers 61%. Nature covers 25% in total and 13 % is forest (Levin et al 2018).

Despite an overrepresentation of agriculture, the Danish landscape shows a significant geographical variation in other geophysical, hydrological and landscape elements such as nitrogen (N) retention, costal nitrogen (N) loads, soil types, soil organic carbon, biodiversity, and farm type and practices. At Danish research institutions and public administrative agencies, these geographical data exist, open source, in a relatively fine resolution, which strengthens the possibilities for conducting landscape analysis and enables a more targeted implementation of NBS for the benefit of aiming at zero pollution.

The chosen Danish NBS site is situated in Northern Jutland and represents part of the Limfjord catchment, which connects the North Sea and the Kattegat and covers an area of 260,000 ha where approximately 63% is agriculture. The land use of the NBS site resembles the average national land use.

Furthermore, the site partly covers the national range of both biodiversity scores (0-16 score – where 20 is the highest at the national level) as well as N retention percentages (5-100%), which makes the site representative for the Danish region.

Still, the Limfjord represents a catchment with some of the poorest water quality and ecological status and thus a higher nitrogen reduction goal relative to the rest of Denmark, in order to fulfil the goals of the European Water Framework Directive.

With a national costal N reduction goal of approximately 13,000 ton N/yr by 2027, approximately 28% of this are to be reduced from the catchment surrounding the Limfjord and half of this should be reduced from the chosen NBS site (1500 ton N/yr).

A key conclusion from previous investigations on policy implementation in Denmark shows that it will not be possible to reduce these amounts of N by implementing only collective measures such as constructed wetlands (SEGES, 2017). There is a need for a combination of measures and a higher level of stakeholder involvement if the goals are to be delivered. One solution of setting aside large amounts of agricultural land could compromise the economic profit of agricultural areas (Ørum et al., 2017), and are therefore not seen as a plausible solution. Therefore, innovative NBS that are targeted at individual catchments with the involvement of relevant stakeholders are needed for socio-ecological transformation.

The Danish partners will assess the NBS from a systems approach thereby helping to define, monitor, and assess NBS effects at field/local, farm, landscape, and regional level - embracing the whole system.

For the Danish site trans4num selected two NBS:

• Changes in crop rotations (Circular and N crop-rotation) towards more biomass crops, including perennial crops, e.g. grass production and grass clover mixtures for biorefinery purposes to produce protein to feed monogastric animals and fiber for ruminants (Hermansen et al., 2017; Børgesen et al., 2018).

A replacement of cereal with grass will facilitate changes in field and crop rotations (local level) and influence farm nutrient balances, local climate accounts, and potentially benefit positive effects in surrounding nature areas and the aquatic environments such as the Fjord (landscape/regional level) (Odgaard et al., 2019b). Furthermore, other farm types using biorefinery products will also be influenced (system level).

• Biobased fertilizer from organic waste.

Use of biobased fertilizers from manure and other waste streams in replacement of chemical fertilizers will increase the circular use of nutrients and potentially decrease N loss to the environment while enhancing the farmer’s profit.

These NBSs both fit well with the general definition of NBS from IUCN: “Nature-based Solutions are actions to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges effectively and adaptively, simultaneously benefiting people and nature”

A targeted approach can be used to distribute the various NBS most effectively across the landscape (landscape/regional level). Hence, the selected NBS can embrace local to regional level effects, depending on the research design. The potential of each NBS to facilitate a more sustainable production will be assessed through desk studies, modelling activities, and interviews. Furthermore, their implementation are discussed with relevant practitioners and evaluated though societal transformation scenarios.

The effect of the selected NBS will be monitored using e.g. remotely sensed data and machine-learning methods. Implementation of these NBS potentially also have positive impacts on soil, climate and biodiversity while also delivering positive effects on rural communities and local economies (Odgaard et al., 2019ab).

The practical partners aligned for the Danish NBS sites and region are Klimafonden Skive, ICOEL (Organic Innovation Center Denmark) and FieldSense (Cordulus) a SMV with expertise in remote sensing for the monitoring and optimization of nutrient flows from NBS. While the scientific partner are Department of Agroecology, Aarhus University.