Arbejdsrapport fra Miljøstyrelsen, 22/2005 – Scenarieberegning af konsekvenser for landbrug ved grænseværdi for nitrat

Arbejdsrapport fra Miljøstyrelsen, 22/2005 – Scenarieberegning af konsekvenser for landbrug ved grænseværdi for nitrat

Summary and conclusions

In this paper the costs of introducing a maximum level for nitrate leaching of 75 and 150 mg nitrate per litre for sandy and sandy clay soils has been estimated for The Danish Environmental Protection Agency. The calculation is based on analyses made by the Institute of Agricultural Sciences showing that 16,000 ha will exceed the above mentioned limits. The calculations have been made on the municipality level where the average leaching within this area is compared with a weighted average based on the distribution of soil types in that municipality. The total required reduction is 59 tonne N, assuming that the Plan for the Aquatic environment III reduces the nitrate leaching by 7.5 kg N per ha.

Catch crops has been chosen as the sole measure as analyses have shown that this measure is cost effective and able to give a reduction in leaching of 30 kg N per ha. The area with catch crops is estimated to be around 2,000 ha, the area should be located where the nitrate leaching is highest. The costs are estimated to 500 DKK per ha. This includes seed, seeding and some costs related to changes in crop rotations. No administrative costs or benefits are included in the calculations.

The total cost is estimated to 1 million DKK a year which correspond to a lump sum of 16 million DKK using an interest of 6 percent and infinite *lifetime. Sensitivity analyses cover changes in the limit for the nitrate content on sandy soil from 62.5 to 87.5 mg Nitrate per. Litre. The analyses show that the cost is between 0.4 and 2.8 million DKK a year. When the uncertainty regarding the implementation of the Plan for the Aquatic environment III (5-10 kg N/ha) is included the minimum cost is 0.2 million DKK and the maximum cost is 3.5 million DKK.

The analysis shows that the level of aggregation is important for the cost estimate. The Danish Environmental Protection Agency have assumed that the municipality level is a suitable proxy for the ground water reserve level. An analysis at the field level will therefore increase the area which exceeds the limit for nitrate in groundwater. No costs for too high pesticide levels been included, as the Agency for the Environment find that the level of 0.1 microgram per litre will not be exceeded.