This report describes the methods and procedures used by the Dutch Minerals Policy Monitoring Programme (LMM) in the years 2011-2014. The LMM provides information on the effects of Dutch minerals policy on agricultural practices and water quality. It plays a role in the accountability and evaluation of the Dutch Fertiliser Law, the European Nitrate Directive and the Dutch derogation of the Nitrate Directive. According to this derogation, the Netherlands has been granted permission under certain circumstances to apply more nitrogen via animal manure than is normally permitted by the Nitrate Directive. It is, however, under an obligation to monitor the effects of the application of larger amounts of nitrogen via animal manure. Several changes were made in the years 2011-2014 to optimise the monitoring network and to adapt it to changing circumstances. The purpose of this report is to describe all the relevant changes in order to clarify the monitoring methods used. The RIVM and Wageningen Economic Research (previously known as LEI Wageningen UR) cooperate in the LMM to collect information about agricultural practices and water quality on Dutch farms. Wageningen Economic Research collects financial, economic and environmental data on approximately 450 farms. The RIVM monitors the quality of groundwater, soil moisture, ditch water and/or drainage water on these farms. The participating farms are a representative random sample covering all the soil regions (sand, clay, peat, loess) and farm types (arable, dairy, industrial livestock and other).

Scientific research points to a possibly increased risk of childhood leukaemia in children who live near overhead power lines. Because of statistical uncertainties and the fact that the disease mechanism is not known, it is not clear whether the magnetic fields of the power lines are the cause. Out of precaution, the Netherlands and several other European countries have developed policies several years ago that aim to reduce the exposure to magnetic fields from new power lines. Different countries deal in different ways with the uncertainties in the available knowledge and strike a different balance between scientific evidence and social, economic and political arguments. These are the findings of an investigation by the National Institute of Public Health and the Environment (RIVM). The report clarifies the policy in the Netherlands on magnetic fields from power lines and compares it with the policies in four nearby countries (Belgium, France, Germany and the United Kingdom). These countries differ in the applied limits and in the locations and types of electricity infrastructure to which the policy applies. For example, the policy in the United Kingdom is the most restrained and is aimed at informing the public and changing the connectivity (phasing) of power lines, for example in power stations, which weakens the magnetic field. Further measures are not deemed proportional to the possible risk. Germany applies a policy that aims to minimise magnetic fields from a broader range of electricity infrastructure, for example also for switch stations and the overhead wires of railways.

Dutch manure policy tries to limit the harmful environmental impact of agriculture. This is in line with international agreements on fertilizer use. The European Nitrates Directive prescribes Member States to limit the use of animal manure to 170 kg nitrogen per hectare. Farms with at least 80 percent of grassland may, under certain conditions, use more manure from grazing animals such as cows and sheep (derogation). Over the last 10 years, nitrate leaching from the manure to the upper groundwater has decreased or remained the same for these farms. By 2015, on average, the concentration is in all regions below the EU standard of 50 milligrams of nitrate per liter. This is according to the annual report by RIVM and Wageningen Economic Research. They follow agricultural practices and the effects on water quality at 300 derogation farms and report their results to the EU annually. This report describes the situation in 2015 and the development between 2006 and 2016 (trend). Management. The permissible amount of nitrogen from grazing manure is, depending on the soil and region, 250 kilograms per hectare (in the Clay region. Peat region and northern part of the Sand region) or 230 kg/ha (in the Loess region and the rest of the Sand region). On average, derogation companies have used 238 kilograms of nitrogen from animal manure per hectare in 2015. The amount of nitrogen that can leached as nitrate to groundwater is determined, among others, by the so-called nitrogen soil surplus. This is the difference between the input of nitrogen (such as fertilizers) and their output (including through grass and maize). The average nitrogen surplus over the regions has decreased over the period considered. Groundwater quality. By 2015, the average nitrate concentration in the groundwater in Sand 250 was 26 milligrams per liter (mg/l). The highest concentration is measured in the Loess region (42 mg/l) and in Sand 230 (45 mg/l). On the average, farms in the Clay region and the Peat region had lower nitrate concentrations in leaching water (22 and 13 mg/l respectively). The difference between the regions can be explained by the proportion of soils prone to nitrate leaching. Especially in Sand 230 and in the Loess region there are grounds for which nitrate is reduced in a lesser extent, and therefore can leach more to groundwater.