Landbouwpraktijk en waterkwaliteit op landbouwbedrijven aangemeld voor derogatie in 2021

Samenvatting

Dutch farms that meet certain conditions, such as a minimum of 80 percent acreage as grassland, may use more animal manure than the general limit prescribed by the European Nitrates Directive. This partial exemption is referred to as ‘derogation’. The National Institute for Public Health and the Environment (RIVM) and Wageningen Economic Research monitor the effects of this derogation on the water quality on 300 farms in the derogation monitoring network. This study concludes that derogation has had no negative effects on water quality since 2006, the year the derogation came into effect. However, nitrate concentrations increased in the past years, especially in the Sand region. This increase is probably due to the droughts occurring in 2018-2020. Drought can lead to higher nitrate concentrations in groundwater in several ways, including decreased breakdown of nitrogen (denitrification). The nitrate concentration decreased in all regions in 2022, probably due to the fact that 2021 was a relatively wet year. Management On average, derogation farms have used 229 kilograms of nitrogen from animal manure per hectare in 2020. The permissible amount of nitrogen from animal manure varies from 230 to 250 kilograms per hectare, depending on the soil type and region. Improvements in management and changes in legislation have resulted in more efficient use of nitrogen for crop production. As a result, the nitrogen surplus on the soil surface balance has decreased on average over the entire measurement period. This means that less nitrogen, in the form of nitrate, was available to leach to the lower parts of soil profiles and eventually into the groundwater. The soil nitrogen surplus was 114 kilogram per hectare in 2021, the lowest of all monitored years. Groundwater quality In the south and the east of the Sand region the average nitrate concentrations in the upper metre of the groundwater in 2022 was 51 milligram per litre. This is higher than the EU-standard of 50 milligram per litre. After rising sharply in this part of the Sand Region since 2017, nitrate concentrations decreased in 2022 compared to 2021. In the north of the Sand region the concentration was lower than the EU-standard, and decreased to 22 milligram per litre in 2021. In the Loess region the concentration decreased slightly to 51 milligram per litre in 2021, but remained above the EU-standard. In the Clay region the nitrate concentrations remained consistently under the EU-standard. After a sharp increase in the recent years, the nitrate concentration in the Clay region was 18 milligram per litre in 2022. In the Peat region the lowest concentrations are measured, with 9 milligram per litre in 2021. The monitoring was commissioned by the Ministry of Agriculture, Nature & Food Quality. In September 2022, the European Commission decided to phase out the derogation for the Netherlands. From 2026, the Netherlands will no longer have a derogation.