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Nitrate in upper groundwater under agricultural land, 1992-2015

Average nitrate concentration in groundwater in the Sand Region has diminished to levels close to the Nitrates Directive. The four-year average of nitrate concentrations in on-farm surface water in the Sand Regions of the Netherlands as measured over the latest reporting period for the Nitrates Directive (2012-2015) is 54 mg/l, down from 58 mg/l over the previous reporting period (2008-2011). In the southern part of the Sand Region, the average concentration of nitrates over these periods decreased from 92 to 81 mg/l, still well above the limit value of 50 mg/l.

Nitrate concentrations vary per area

In the Loess Regions, the average nitrate concentration in surface water on farms over the latest reporting period for the Nitrates Directive (2012-2015) was 75 mg/l, also well above the 50 mg/l limit value. There is barely any improvement in these regions compared to the previous reporting period (2008-2011). In the Clay and Peat Regions, nitrate concentrations in upper groundwater are much lower than in the Sand Region, because more nitrate is broken down. As a result, the average concentrations are well below the limit value.
Except for the Loess Region, nitrate concentrations have increased in all soil regions since 2012. This increase is not due to a lower precipitation excess, however this period is too short to find any further explanation. Although the average in the Sand Region is within reach of the 50 mg/l level, almost half (46%) of those farms which were sampled in the Sand Region do not comply with the limit value, including dairy farms (around 20%) and arable farms (70%). Large deviations are seen within the Sand Region. In the southern Sand Region (Noord-Brabant and Limburg province), the average nitrate concentration is higher at 81 mg/l than in the northern (34 mg/l) and central (44 mg/l) Sand Region. This difference is partly due to the fact that crops in the south are relatively more prone to leaching (i.e. crops which, when fertilised based on specifications, have a nitrate concentration exceeding the prescribed limit value of 50 mg per litre), the higher prevalence of soils which are more vulnerable to nitrogen leaching and the presence of many intensive (granivore) livestock farms with high quantities of manure and small land areas.

Decline in nitrogen surpluses stagnating

The trend as seen in nitrogen surpluses on agricultural land (i.e. amount of nitrogen not absorbed by plants and potentially leaching to upper groundwater or surface water) determines the trend of nitrate leaching. As described in the Nitrates Directive reporting (RIVM, 2016), the average nitrogen surpluses on the surface soil balance for dairy cattle farms as well as arable farms in all soil regions over the period 2011-2014 were lower than in the previous period (2007-2010). However, nitrogen surpluses at dairy cattle farms in the Sand Region have declined increasingly slowly while surpluses in the Clay and Peat Region have not declined since 2003. Nitrogen surpluses in surface soil at arable farms have barely decreased since 2000, both in the Sand and in the Clay Region (RIVM, 2016). The nitrogen surplus has not declined in recent years as there has barely been a further decrease in application standards for nitrogen, the use of nitrogen fertilisers and the amount of nitrogen in animal manure per hectare of agricultural land. The decrease in agricultural area suitable for fertilisation may be a factor here, as this provides an extra incentive to maximise the space for animal manure application.
Over the entire monitoring period 1991-2015, the trend in sampled nitrate concentrations in the Sand Region is fairly similar to the trend of nitrogen surpluses in soil. This supports the policy view that a manure policy which is focused on decrease of nitrogen surplus is effective in reaching the nitrate target. In 2014, nitrogen application standards for crops vulnerable to leaching in the southern Sand Region were tightened by 20%. The effects of this measure on the magnitude of nitrate leaching cannot be measured as yet.

References

  • Fraters, B, A.E.J. Hooijboer, A. Vrijhoef, J. Claessens, M.C. Kotte, G.B.J. Rijs, A.I.M. Denneman, C. van Bruggen, C.H.G. Daatselaar, H.A.L. Begeman (auteur), J.N. Bosma (2016), Landbouwpraktijk en waterkwaliteit in Nederland; toestand (2012-2014) en trend (1992-2014). Resultaten van de monitoring voor de Nitraatrichtlijn. RIVM Rapport 2016-0076
  • Willems J., M. van Schijndel, H. van Grinsven, F. Kragt, H. van Zeijts, J. van Dam, G.J. van den Born & S. van der Sluis (2012), Evaluatie meststoffenwet 2012. Den Haag: Planbureau voor de Leefomgeving

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Reference for this page

CBS, PBL, RIVM, WUR (2017). Nitrate in upper groundwater under agricultural land, 1992-2015 (indicator 0271, version 10 , 29 March 2017 ). www.environmentaldata.nl. Statistics Netherlands (CBS), The Hague; PBL Netherlands Environmental Assessment Agency, The Hague; RIVM National Institute for Public Health and the Environment, Bilthoven; and Wageningen University and Research, Wageningen.

The Environmental Data Compendium is a partnership of CBS, PBL, RIVM and WUR.