Denmark has to comply with the EU Water Framework Directive on good ecological status for all water bodies. One of the main factors influencing the aquatic environment is the input of nitrogen, including that from agriculture. It is therefore important to document how different initiatives can affect the agricultural emission of nitrogen to the environment.

Scientists and other experts from Aarhus University and University of Copenhagen have analysed and described the potential measures that can be used to reduce agricultural losses of nitrogen to the environment. The analysis is to be used as part of the decision support system for the second generation of water management plans and future differentiated agricultural regulations. The results have just been published in a report by DCA - Danish Centre for Food and Agriculture at Aarhus University.

Two categories of measures

The scientists analysed 26 different measures that are divided into two categories:

Category 1 consists of measures that can potentially be used in connection with the second generation of river basin management plans and includes voluntary or compulsory measures (both targeted and general). Typical of this category are measures that do not involve growing crops on farmland and therefore do not have an effect on future field management plans.

These areas include the use of wetlands, stone reefs, planting of common eelgrass, kelp and algae production, mussel farming, wide/intelligent buffer zones, removal of biomass in the buffer zones, removal of biomass from low-lying areas, afforestation, buffer zones and permanent fallow.

Category 2 consists of measures that can potentially be used in conjunction with new, targeted area-specific regulations. Typical of these measures is that they for the most part will have an impact on the way the fields are cultivated when the measure is put into practice.

The category 2 initiatives include: cover crops, break crops, set-aside (temporary), crops with a high nitrogen uptake, ban on soil tillage in certain periods, ban on conversion from forage grass in the autumn, ban on livestock manure application in the autumn, incineration of the fibrous fraction, using straw for biogas production and returning the biochar to the soil, early sowing of winter wheat, incorporation of straw before winter crops, conservation tillage, site-specific fertilisation, mini-wetlands – constructed wetlands, controlled drainage and perennial energy crops.

More information on the way

There is not sufficient data to estimate the nitrogen effect for all the measures listed in the catalogue. In those cases more data will need to be collected or tests carried out before an effect can be calculated. For some of the instruments, projects have already been started that are expected to provide the documentation needed in the coming years.

Besides the nitrogen effect of the measures, the report includes a description of their secondary effects and side effects in relation to phosphorus, nature/biodiversity, impact on climate and pesticide use as well as an economic assessment of the cost of removing one kilogram of nitrogen.

The report has been compiled by DCE - Danish Centre for Environment and Energy and DCA - Danish Centre for Food and Agriculture at Aarhus University with contributions from authors from the Department of Agroecology, Department of Bioscience and the Department of Environmental Science, and from the Department of Food and Resource Economics at the University of Copenhagen.

The DCA report no. 52, December 2014, has been published in Danish and is available from here. It has been prepared on the instruction of the Ministry of Food, Agriculture and Fisheries, the Ministry of the Environment and the Ministry of Climate, Energy and Building.

For further information please contact:

For general information and Category 2 measures:

Professor Jørgen Eriksen, Department of Agroecology, e-mail: jorgen.eriksen@agro.au.dk, telephone: +45 8715 7672, mobile: +45 5168 0554

For Category 1 measures:

Senior Consultant Poul Nordemann Jensen, DCE - Danish Centre for Environment and Energy, email: pnj@dce.au.dk, telephone: +45 8715 8793