UvA nitrogen study vague in words, clear in results

In their words, the UvA researchers clearly wanted to save the money and the goat, but anyone who reads the report carefully will see that the results about the behavior of nitrogen emissions from dairy farms are crystal clear and clear.

Also read:

• UvA research sets the agricultural cut-off limit at 300 meters
• In practice, nitrogen emissions deviate significantly from the model

He calls it 'startling' Algemeen Dagblad the one published on Tuesday nitrogen deposition study from the University of Amsterdam. In line with the Telegraaf concludes the newspaper for a broad audience that has come to the end of the farmer's buyout policy. In contrast, conclude Trouw en NRC - newspapers for a highly educated audience - that the UvA research proves the government right. The boerophile magazine Dairy Cattle notes that nitrogen can no longer be traced back to a farmer after 300 meters. Nitrogen is therefore not a local problem, as has been the scientific consensus to date. What are the facts and what can explain such a large difference in interpretation?

The researchers themselves put it as follows. More than 90% of the total emissions of ammonia from stables and manure - commonly called 'farmer nitrogen' - are dispersed in the upper atmosphere and transported over distances of more than 500 meters. This means that about 10% of the total emissions from the stable and manure on the field fall as nitrogen deposition within a radius of 500 meters around the stable. The farm still has an effect 500 meters and further from the stable, but the contribution of one specific company outside the 500 meter circle is low compared to the background concentration of ammonia. By taking background values ​​and effects of fertilization into account, the study was able to determine which part of the measured atmospheric ammonia came from the stable. This share decreased with the distance from the stable: at 25 meters from the stable, 75% of the ammonia concentration came from that stable, while at 500 meters only 25% of the ammonia concentration came from the stable.

These sentences can be found almost literally in the text of the UvA researchers.

Distribution and deposition
In the press release about the research, the UvA formulates the same news as follows: On behalf of the Mesdag Zuivelfonds, researchers from the University of Amsterdam measured in which circle around dairy farms the nitrogen emitted falls. By far the largest part of the emitted nitrogen (≈ 90%) ends up in higher air layers of the atmosphere and will precipitate elsewhere. Within the measured area with a radius of 500 meters around the farm, most of the remaining part (≈ 10%) precipitates within a radius of 100 meters. These results are in accordance with previous research and the RIVM models.

The last sentence is read by Trouw and NRC as a confirmation that the nitrogen models that the RIVM uses on behalf of the government to calculate the dispersion (how far does it reach?) and deposition (where how much is deposited?) of ammonia emissions are correct. However, anyone who reads the research report carefully will note that the deposition attributable to local ammonia emissions is negligible. That is a conclusion that is quite at odds with the idea behind the nitrogen policy and the calculations of the models. These are built on the theoretical premise that agricultural nitrogen has its harmful effect on nature nearby. The researchers note that this is not the case. They further note that the small amount of nitrogen that does precipitate locally mainly precipitates on the farmer's own property and nearby land. NRC and Trouw do not see enough that the researchers are trying to spare the cabbage and the goat. They subtly say that the RIVM is doing a good job in calculating the spread. But what about deposition?

'No form of validation'
On page 15 you can read that the researchers cannot validate the deposition - the harmful precipitation that is the focus of Dutch policy - in any way because the results of the calculation model used by the government differ too much from the actual measurements of the UvA. . That is a deadly sentence for nitrogen policy, but it takes some insight to understand the meaning of those apparently coldly written words. In English, the researchers formulate this sentence: With regard to total NH3 deposition we think the model output is consistent with the observations, but we can't claim a good match nor any form of validation because the observed entities (bulk deposition measurements) are different from those represented in the OPS model. In plain English: the researchers note that assumptions in the model cannot be confirmed in any way by their actual fieldwork. In Dutch professional language: if this research is seen as a test of the model, it must be noted that the facts cannot validate the model. In other words: the model is based on theoretical assumptions that do not correspond to empirical reality.

Sticking to a flat earth
Some calling back and forth provides an idea of ​​what seems to have happened. The Amsterdam researchers did not want to offend the RIVM and the government too much. The story corresponds to the anecdote with which the famous American sociologist of science Thomas Kuhn explained why, according to Cardinal Bellarmino, the world had to remain flat, while Galileo and Bellarmino himself - a man who was interested in new scientific insights - knew that it is round and revolves around the sun: 'then no one will believe our policy and our objectives anymore'. Translated to our time and this dossier: because politicians, media and the public think that the earth is flat, it should remain that way otherwise no one will believe that we should limit nitrogen emissions. The media themselves appear to be divided into believers and non-believers and lack the cool gaze of an observer who looks critically at the different churches.

Blanket
Nitrogen, like carbon, appears to be a 'blanket' issue. It doesn't so much have a local source for a local problem. This does not mean that there is no nitrogen deposition, but it does mean that it is brought in by the wind and comes down with the rain (as Nico Gerrits showed in one of his first contributions on the subject). The problem that extra fertilizer in the form of nitrogen is supplied to nature reserves that thrive where you want poor nature will therefore continue to exist. However, the extent to which it precipitates somewhere is not correctly calculated by the RIVM: the calculations of the models are contradicted by field work. It is also clear that nitrogen deposition is not an issue - contrary to what policy has thought so far - that can be meaningfully tackled locally. Nitrogen ends up high in the air, is probably (consistent with basic chemical knowledge) transported over great distances by the wind and returns to the earth through the rain. That is why it cannot be solved by only removing local emission sources, such as buying out farmers or relocating companies such as Rockwool (one of the largest industrial emitters of ammonia in our country).

NRC and Trouw overlook this news that has finally been made plausible through field work. Perhaps it is easier for our readers to understand from the report, because we have been looking critically at the models here for almost ten years and approaching them from chemical and physical insights and we are not so tied to Bellarmino's concerns and prefer to be clear.

The scientific journal Nature published a Chinese study indicating that there are more significant sources of ammonia than livestock farming. By an unfortunate coincidence, the FDF released it yesterday at the same time as the above research from the UvA. That is also not only with us, but also with TNO known for years. Now that the UvA report has been published, it is time to recalibrate thinking about nitrogen policy. A number of questions require fresh answers from outside the familiar groove. What do we actually know about nitrogen emissions and the damage they cause to nature somewhere? What do we want to achieve, what measures are needed to achieve our goals and what do we need to know to be sufficiently certain of the results of measures? Which laws and regulations are part of an effective package of measures (and which are not)? And if nitrogen is indeed a blanket issue just like carbon, among other things cars with catalytic converters and industry contribute to this, what nature conservation measures are needed to no longer treat mobility and industrial activity as the elephant in the room?

Spicy Schiermonnikoog
The most interesting aspect of the UvA research is the refutation of Minister Van der Wal's statement why farmer deposition increased instead of decreasing after the significant reduction in the number of cows on Schiermonnikoog. In picture 5 on page 14, the researchers show that nature no longer experiences any effect from ammonia 150 hours (less than a week) after fertilization. According to Van der Wal deposition does not decrease and the effect - lower deposition - only becomes visible after many years. The UvA researchers belie that statement. It's high time for a new episode of Sjors & Sjimmie on Schiermeeuwenoog.

It is plausible to think that nitrogen deposition is a consequence of rainfall. However, that idea has major consequences for thinking about nitrogen, but does not make the blanket thinner, as the more popular newspapers seem to suggest. Nor is there much that can be done locally about the problem, as NRC and Trouw seem to want to maintain. The merit of the UvA research is that it shows that the government should think in terms of emissions and not in terms of deposition and that this must be done at a European level to stop the blowing in through the back door and not to cause transit through the front door. The latter because nitrogen blows into our country from mainly Belgium and France and falls here with rain; our nitrogen is blowing through again, mainly to Germany. The RIVM distribution model also knows this. However, it calculates how much is true on theoretical grounds for which the UvA says it cannot find any confirmation in practice. It must be examined whether the much-troubled Aerius model can calculate the precipitation more accurately so that it can be confirmed by the actual field work of the UvA.

An answer to the question of whether the UvA research undermines the peak load policy. The UvA researchers do not dare to formulate it clearly, but they do say it out loud: it is based on an validated model that calculates depositions that they have not been able to find in practice.

This article is part of the content collaboration between Boerenbusiness en foodlog.