The farmers protests began on Wednesday in an exceptional location: in De Bilt, near the National Institute for Public Health and the Environment (RIVM). They did so because the science underlying the nitrogen measures was no good. That is why, according to the farmers, the nitrogen measures must be revised.

The Farmers Defense Front action group, for example, spoke of "shadowy and non-public methods" and Agractie has a list of points of criticism, including alleged use of a "scientifically prohibited method".

The Mesdag Zuivelfonds interest organization has even announced that it will start a lawsuit against the RIVM, because the institute does not want to open up the nitrogen model used.

Some political parties have also criticized the RIVM: CDA, VVD and SGP express their doubts about the reliability of nitrogen measurements. CDA MP Jaco Geurts in the AD not only doubted the calculation model, but also said that there would be no openness about the measurements.


Demonstrating farmers gather in De Bilt

Nitrogen measurements and methods are public

In a response to, a spokesperson for the RIVM said that it was particularly difficult to do so: the institute would always be as transparent as possible. All measurements are publicly accessible, as is the information about the calculation model.

The only exception is the "raw data", because it must first be assessed whether there are measurement errors due to malfunctions. This is to prevent incorrect information from being distributed, according to the RIVM.

In an interview with de Volkskrant , nitrogen expert Jan Willem Erisman from the Louis Bolk Institute agricultural research center also says that RIVM measurements and methods are indeed public. And if the calculations of the model used are incorrect, according to Erisman that would be a few percent, not the big picture.

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Two disputed measurement stations at farms are only a back-up

Agractie has even more criticism of RIVM. For example, only six measuring stations would be used, two of which are close to a chicken farm and a pig farm. These measurements would therefore be too high and not representative. Agractie also argues on the one hand that it cannot be demonstrated that nitrogen compounds can travel long distances through the air, and on the other that it cannot be demonstrated that the nitrogen compounds precipitate on the ground in nature reserves.

The RIVM says that the two disputed measuring stations are not used to determine the nitrogen deposition. But more importantly, the measurement stations only function as a backup for the calculations made by a model.

Precisely because so many nitrogen sources exist in the densely populated Netherlands, the RIVM is looking at the amount of road traffic, industrial combustion and agricultural activity. That emission data is converted into concentrations and nitrogen precipitation by an air quality model.

The measurements are only used to check whether the nitrogen model has indeed made a correct calculation at a certain location. If there appears to be a deviation, the model is corrected for this.

In addition, it is not just six measurement points, but much more. In addition to the six ammonia measurement points in inhabited areas, the model is also tested with 45 measurement points for nitrogen oxides. There are also eight measuring stations that can be used to compare the precipitation of nitrogen via rain with the model calculations, and four measuring sites for so-called 'dry deposition' in plants and soils. In addition, RIVM measures the air concentration of ammonia in more than eighty nature areas.

The RIVM is relatively short about the movement of nitrogen through the air: it can, for example, remain in the air for a few hours after manure has been applied. How far it moves before it settles on the ground depends on the wind: a few tens of kilometers at most.


Why does nitrogen cause so many problems in the Netherlands?

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Nitrogen fertilization leads to displacement in nature reserves

In addition to all criticism of the RIVM, Agractie even disputes that nitrogen is harmful to Dutch nature. In May, however, the Council of State ruled that Dutch nitrogen policy is contrary to European legislation and causes too much damage to nature.

What then is the problem for nature? This is due to two effects. Firstly, the over-fertilization with the nitrogen itself. In itself, nitrogen is an important nutrient that many plants need. But if there is too much in the soil, certain fast-growing species, such as grass and nettle, can displace a greater diversity of other plants.

In grasslands, for example, this comes at the expense of natural flowering herbs, which in turn are important for pollinating insects and meadow birds. The other problem is acidification of the soil. As a result, shortages of other minerals, such as calcium and magnesium, occur in nature reserves that have to buffer the acidity.

See also: The damage caused by nitrogen: 'Nature becomes a fast food restaurant'

Flowering grasslands disappeared, Veluwe loses many birds

Does all nature suffer the same from nitrogen pollution? No, it mainly concerns nature areas that have their own biodiversity because of a nutrient-poor soil, which is being suppressed by more general species through fertilization. These are naturally the sandy soils in the east and south of the Netherlands, and also the (high) peat areas. Low-nutrient flowering grasslands that used to be common, have almost completely disappeared from the Netherlands due to over-fertilization.

Those problems of over-fertilization, acidification and desiccation coincide in, for example, the Veluwe, according to twelve ecologists in Vrij Nederland . A third of the oaks have since died and many bird species have disappeared because there is no longer enough calcium and magnesium in the soil to produce hard eggshells. The young males are even born with soft bones because of the mineral disturbances in the Veluwe that they already break their paws in the nest. The cause, ecologists say: nitrogen, mainly from intensive agriculture.