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Tommy Dalgaard

Targeted set-aside: Benefits from reduced nitrogen loading in Danish aquatic environments

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Nitrogen (N) surplus form agricultural production is currently one of the most influential sources of eutrophication in coastal waters. Danish policies implemented to lower coastal N loads has previously been applied at the national scale without acknowledging spatial variation in e.g. N retention soil capacities from source to recipient and synergetic effects from the implemented measures on the surroundings (e.g. nature areas and production value of agricultural areas).
With Denmark as study region, our goal was to assess the effect of spatially targeting N measures (using set-aside as an efficient measure) according to different criteria for where to place set-aside, in all cases reaching the N reduction goals set out by the Danish water management plans using only agricultural areas. Three criteria were considered: 1) costal N load (kg N/ha/yr), 2) nature value of the surroundings, and 3) land rent, which is a measure of production value of agricultural fields (DKK/ha/yr), thereby favoring agricultural areas with high N loads, close to nature, and low land rent. These three criteria were then combined resulting in three individual multifunctional scenarios (GreenEnvi - N load dominates, TerreEco - Nature dominates, AgroEcon - land rent dominates).
Results show that targeting for coastal N load require 23% of the agricultural area set aside to reach the 90 coastal water catchments N reduction goals, but 36% when targeting for nature, 37% for land rent, and 35% when using no targeting. Hence, there is a clear benefit using targeting over no targeting in sense of less agricultural area lost when targeting for N load. Furthermore, the scenario GreenEnvi takes up 25% of the agricultural area. Simultaneously, this scenario is slightly cheaper and effects a larger nature area than targeting for e.g. N load. Hence, multiple benefits could be achieved if willing to take up marginally more of the agricultural land - 23 to 25%. Another result indicates that it is less costly to target for N load than for land rent. This is interesting as it illustrates a possible decoupling of low costal N loads and low land rent thereby facilitating socio-economic benefits only focusing on areas with high N loads - despite the isolated soil production value.
Original languageEnglish
JournalJournal of Environmental Management
Volume247
Pages (from-to)633-643
Number of pages11
ISSN0301-4797
DOIs
Publication statusPublished - 2019

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