Upward Revision of Restrictions on Nitrogen Applications in Denmark

Keywords: nitrogen regulation, regulation of nitrogen input; value of protein and optimal nitrogen supply, yield and optimal nitrogen rates.

In Denmark regulation of the use of manure, fertiliser and land use started in 1985. The current regulation is based on a plan for sustainable agriculture developed in 1991, where nitrogen (N) quotas and fertiliser accounts were introduced.

In the period between 1999 and 2016 the N-quotas were based on sub optimal N-rates. However a political agreement in 2015 stops the demand for fertiliser quotas below the economic optimum, coming into effect in 2017. The regulation of the use of nitrogen has been very effective, and the use of nitrogen in mineral fertiliser has been reduced by 50%. The loss of nitrogen into coastal waters has declined by nearly 50% from 1990 to 2014, but it is difficult to see an improvement in the ecological status in the sea.

The sub optimal N-quota has resulted in a higher loss of income for agriculture than was expected. Under-fertilisation has increased because the need for nitrogen has increased over time due to higher yield potentials, and lower mineralisation of nitrogen from the soil because of lower input. In addition, increasing prices of protein have led to higher demands for nitrogen. If the value of protein in feed is included when calculating optimal N-rates for winter wheat, the optimal N-rate has increased by approximately 30 kg N/ha. The total loss of income in agriculture as a consequence of reduced quotas has been calculated by SEGES to be €300 million per year (€140/ha).

A political agreement in 2015 stopped the requirement for fertiliser quotas below the economical optimum, but kept the target for reducing nitrogen loss nearly unchanged. The higher nitrogen quota will lead to an increased loss of nitrogen, and must therefore be countered by other instruments to reduce the loss. Collective initiatives such as wetlands, constructed wetlands and afforestation are examples of other possibilities. However a significant need to reduce the amount of loss from catchments into vulnerable fiords and inlets will probably result in new nitrogen restriction quotas and higher demands for mandatory catch crops on agricultural land.

Leif Knudsen SEGES, Agro Food Park 15, Skejby, Århus, Denmark.

19 pages, 10 figures, 5 tables, 13 references