Agricultural practices and water quality in the Netherlands: status (2020–2023) and trends (1992–2023) : the 2024 Nitrate report with the results of the monitoring of the effects of the EU Nitrates Directive Action Programmes

Nitrogen and phosphorus in fertiliser improve crop growth. When farms use fertiliser, nitrogen and phosphorus leach into the groundwater and surface water, causing pollution. One of the forms in which nitrogen occurs in soil and in water is nitrate. Every four years, RIVM, together with five other knowledge organisations, reports on the quality of groundwater and surface water, and on developments in water quality through the years. Clean groundwater and surface water is important for drinking water production. Clean surface water also serves as a habitat for a wider variety of plants and animals. The amount of nitrogen and phosphorus in groundwater and surface water decreased significantly from the 1990s, resulting in improved water quality. This is mainly because farmers were required to use less fertiliser. That decrease has stopped since 2012. Between 2020 and 2023, nitrate concentrations rose compared to the previous measurement period (2016–2019). This is most probably due in part to the dry summers of 2018, 2019 and 2020. During drought, crops absorb less nitrogen, leaving more nitrogen in the soil. Nitrate concentrations have started to decrease again since 2021, but they are still higher in the Sand and Loess region than they were before the dry summers. At more than half of the farms in the Sand and Loess region, nitrate concentrations in the groundwater are often still too high for clean groundwater and surface water. When the measurements are taken in deeper layers in the soil, the concentrations get lower. Due to an excess of nitrogen and phosphorus in surface water, the biological water quality in many bodies of water in the Netherlands is poor. Among other things, this can lead to too few different species of plants and animals in those habitats. The biological quality of the water is not sufficient in 44 percent of the bodies of water in the Netherlands. In 11 percent of the bodies, nitrogen and phosphorus concentrations are high, but there are still enough species of plants and animals. However, there is a chance that these species will eventually be affected by the high concentrations. Between 2020 and 2023, the water quality in some surface water bodies improved, but in others the quality deteriorated.