PR - ECONOMIC GAINS FROM TARGETING MEASURES BASED ON DETAILED NITRATE REDUCTION MAPS
From 1990 until 2003 Denmark has reduced N-leaching from the root zone by 50%. However, more measures are required and in recent years the focus has been on how to differentiate measures in order to ensure that measures are implemented where the effect of N-reduction per ha of the measures is the highest. The purpose of the NiCA project has been to estimate the nitrate reduction potential in greater detail than before using a plot size of 1-25 ha. This article builds on these findings and presents the possible economic gains to the farmer when using this information. Targeted measures are especially relevant where the N reduction at the field level varies largely within the same farm. In this paper, the knowledge of spatial variation in N-reduction potential is used to plan where to place measures such as catch crops or set a side in order to gain the largest effect. The detailed N-reduction map is used on 10 farms in the Norsminde Catchment near Århus, Denmark. The findings suggest that the average farm would gain approximately 100-150 DKK per ha per year from targeted measures as opposed to not knowing where to place the measures. The analysis indicates that the economic gain is higher than the costs of providing the detailed maps, which are estimated to be 40-60 DKK/ha/year. When reduction requirements are increased, the economic gains are higher. When combined with new measures like mini wetlands and early sowing, the economic advantage is increased further. The paper also shows that not all farms can use the detailed information on N-reduction and so there is not a clear link between spatial variation in N-reduction at the farm level and possible economic gains for these farms.
Keywords: Nitrate reduction, spatially distribution, site specific regulation, targeting, non-point pollution, cost-effectiveness