Nitrogen deposition, 1990-2024

Trend

Dry deposition accounts for the largest share of nitrogen deposition, while smaller amount of nitrogen is deposited through wet deposition. The national average nitrogen deposition in 1990 was over 2,700 mol N/ha. Nitrogen deposition dropped to levels around 1,475 mol N/ha in 2010. Limited decreases in emissions caused deposition remaining stable from 2010 to 2017. Ammonia emissions increased during these years, partly due to the abolition of milk quotas, which led to higher agricultural production. Another factor was improved air quality, which slowed the formation of particulate matter from ammonia (see also Relatie ontwikkelingen emissies en luchtkwaliteit, in Dutch). Since 2017, nitrogen deposition has slightly decreased to approximately 1.315 mol N/ha in 2023 due to a reduction in ammonia emissions. This reduction is partly the result of fewer animals being kept and lower amounts of fertilizer being applied (CBS, 2024). Compared to 2023 the deposition increased in 2024 (based on a provisional figure). Meteorological factors can cause annual fluctuations in deposition of approximately 10%.

The decrease in nitrogen deposition from 1990 to 2023 is the result of lower emissions of both nitrogen oxides (NO_x) and ammonia (NH₃) (see Grootschalige luchtverontreiniging: Uitstoot van NEC-stoffen, in Dutch):

• The emission of nitrogen oxides in the Netherlands has decreased by 76% since 1990. This reduction is the result of measures taken in the transport sector (including the introduction of catalytic converters), in industry, and in the energy sector.
• Ammonia emissions in the Netherlands have decreased by 66% since 1990. This decrease is mostly due to measures implemented before 2010, such as changes in feed composition, the use of low-emission stables, the covering of manure silos, and the direct incorporation of manure during application.
• Emissions of other countries for ammonia and especially for nitrogen oxides have also decreased during the same period.

The extent to which critical loads are exceeded in Natura 2000 areas can be found at Overschrijding van kritische depositiewaarde (in Dutch). For a variety of ecosystems the deposition rates exceed the critical loads necessary for maintaining environmental quality: Environmental quality of terrestrial ecosystems: nitrogen deposition.

National patterns of nitrogen deposition

There are large regional differences in the deposition of nitrogen compounds. In particular in areas with intensive livestock farming, such as the Gelderse Vallei and the Peel, nitrogen deposition can reach levels of more than 3,500 mol N/ha. This is due to the high local ammonia emissions from intensive livestock farming. Ammonia is emitted close to the ground and is deposited relatively quickly, therefore ammonia tends to be deposited closer to the source than nitrogen oxides. However, this does not mean that ammonia mostly deposits locally. On the contrary, most ammonia is deposited over a larger area of tens to several hundreds of kilometres from the source. The roughness of the terrain plays an important role here. Areas with a greater terrain roughness (for example, a forest or a city) capture more nitrogen than a smooth terrain, influencing the dispersion of ammonia over long distances.

About two-thirds of the nitrogen deposition originates from Dutch emission sources. Dutch agriculture contributes about half and is the largest source of nitrogen deposition in the Netherlands. See also: Herkomst stikstofdepositie (in Dutch).