Nationwide, ambient groundwater monitoring approaches in Europe for monitoring the effectiveness of the Nitrates Directive Action Programs
National Institute for Public Health and the Environment
Introduction: Use of nitrogen and phosphorus in agriculture increased rapidly after the Second World War in Europe, increasing agricultural production but also pollution of waters. This was recognized by policy makers in the European Union and led to the adoption of a directive to abate the nitrate pollution of waters by agriculture in 1991 - the Nitrates Directive. This directive obliges Member States amongst others to designate Nitrate Vulnerable Zones; make Action Programs that regulate nitrogen use in agriculture; to monitor the effects of these Action Programs and to report every four years to the European Commission. There are large differences between countries with respect to use of surface water and groundwater, and with respect to the intensity and structure of the agriculture. There seems, however, no relationship between intensity of agriculture and whether Member States have designated Nitrate Vulnerable Zones, or whether they apply their Nitrates Directive Action Programs to the entire territory. Member States regulate nitrogen use by use standards for artificial fertilizer and animal manure. Derogation with respect to the maximum allowable nitrogen application rate of 170 kg/ha of N with manure is only applied for or considered by Member States with larger regions with a substantial livestock density. Farmers are judged on the basis of their nitrogen use and use of other prescribed measures, not on water quality. Monitoring approaches: All Member States are required to monitor their groundwater, surface water and the effectiveness of their Action Programs. There are no regulations for monitoring; only (draft) guidelines have been published by the European Commission. Guidelines for four-annual reporting to the Commission have also been published. Member States are investing a lot of time and money in monitoring networks, with several Member States still extending their networks. There was an agreement on the general strategy for effect monitoring of the Action Programs and the fact that this does not imply that all Member States have to monitor in the same way. Some Member States use regular groundwater and surface water monitoring networks for effect monitoring, while others use quick response networks. Two different approaches of effect monitoring were defined: up scaling and interpolation. The up scaling approach uses the results of studies on effects of changes in agricultural practice on nitrate leaching (and water quality) on experimental sites (e.g. plots or parcels). Process models and data on national-scale change in agricultural practice are used to upscale the experimental-sites results to describe the effect of the Action Program on nitrate leaching and water quality on the national scale. Countries employing an approach that could be classified as up scaling include Denmark, Sweden and the United Kingdom. The interpolation approach uses the results of the monitoring of agricultural practice and nitrate leaching (and water quality) on a random sample of locations, e.g. farms. Statistical models and national-scale monitored changes in agricultural practice are used to describe the effect of the Action Program on nitrate leaching and water quality on the national scale. Countries employing an approach that could be classified as interpolation include Austria, Belgium, Germany, Ireland and the Netherlands.