By stacking and averaging the calculations of different weather models, the most probable line of the weather forecast is created. The same should be done with the calculation of nitrogen emissions and deposition. That is what Geesje Rotgers of the AgriFacts Foundation (STAF) says.
Stand-alone calculation models have too many uncertainties and inaccuracies. Rotgers concludes that the Ministry of Agriculture continues to stick to the Aerius Calculator and does not want to calculate with other available European scientific models.
Hordijk Critical Committee
According to the Hordijk Committee, the uncertainty of the Aerius Calculator at a local level is too great for permits to be granted. The committee was set up by Minister Schouten after the House of Representatives, through motions initiated by the CDA and VVD, urged an investigation into the validity of the RIVM calculations on nitrogen emissions and precipitation. In June 2020, that led to the final report of the advisory board 'Measuring and calculating nitrogen'
The AgriFacts Foundation calculated the figures using European models such as Lotos-Euros and Emep, which the renowned Dutch consultancy firm TNO also uses. They conclude that there are deviations of 50% in the amount of ammonia that precipitates per hectare per year, compared to the results of the Aerius Calculator.
Rotgers: "If LNV would only use the European models Lotos-Euros and Emep, then the target for agriculture for 2030 has already been achieved. The differences between the calculation models are so great. We do not get an answer from the ministry as to why they not calculate the consequences of the policy using multiple models, while the Hordijk Committee has recommended that."
In the letter to parliament that Minister Schouten devoted this week to the findings of the Hordijk Committee, she emphasizes the general conclusion of the advisory board that the measurement and calculation methods used by the Ministry of LNV are basically sufficient.
Adopted Recommendations
However, the government has adopted a number of recommendations. For example, expanding the number of monitoring networks. Rotgers: "When it comes to measurements of deposition, that's a good thing. The University of Amsterdam also started a study this spring that uses various techniques to measure ammonia and NOx throughout the Netherlands."
The Hordijk Committee is critical of the use of Aerius Calculator as part of the licensing process, the minister also acknowledges. That is why we are constantly working on the development of the model (a new release with updated data will follow this afternoon, Thursday 15 October). At the same time, she notes that there is currently "nowhere in the world a better method for issuing permits."
In the letter to parliament, the minister also mentions the possibility of considering the use of satellite images, as recommended by the Hordijk Committee. The European Union is also working on this, says Rotgers.
The minister also states that he will commission research into broadening the lower limit, whereby projects with less than 0,005 mol deposition per hectare per year do not require a nature permit. But that does not stop the minister from continuing to use the much-criticized lower limit for permits for the time being, which can accelerate from today due to the update of the Aerius Calculator.
Many questions about Nox vs Ammonia
The questionable distinction between calculations of NOx emissions and precipitation from traffic and industry and ammonia emissions from livestock farming is also no reason for the minister to change policy. Once again, she announces research, but in the short term, adjustment would delay the licensing process. Rotgers: "The AgriFacts Foundation also gets a lot of questions about this." The Hordijk Committee concluded about this distinction that improvements in the short term are indeed possible that remove the imbalance in the calculation method between NOx and ammonia.
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