Water quality on farmlands. Evaluation of the Fertilizers Act 2007
Waterkwaliteit op landbouwbedrijven. Evaluatie Meststoffenwet 2007
26 May 2012, PDF |
51 pages |
Hooijboer AEJ, Fraters B, Boumans LJM
RIVM Report 680130002
The nitrate concentration of the upper groundwater on farmlands in sand regions exceeds the standard of the European Nitrate Directive (50 mg/l). The implementation of the minerals policy has resulted in a gradual decrease in the nitrate content until 2002, following which time, the nitrate content has stabilized. The nitrate standard is generally not exceeded on farms in clay and peat areas, although there is no clear relation between the minerals policy and nitrate content. A decrease in the nitrate content of groundwater and ditch water on agricultural enterprises reduces the nitrate load on the environment. The average nitrate content differs for different types of farms. The upper groundwater on dairy farms has generally the lowest nitrate content, with 50% of all dairy farms in sand regions meeting the European standard. In contrast, crop farms fall below this level, with only 30% of crop farms in sand regions meeting the standard in groundwater. Only 20% of all industrial-scale animal farms, such a pig farms, meet the standard; these farms have, on average, the highest nitrate content. Ditchwater is also monitored on farms in clay and peat areas. The total nitrogen content (including nitrate) of ditch water is above the standard established for ecological risks (Maximum Permissible Concentration).