News Nitrogen
'Calculation model for critical deposition value flawed'
The calculation model for the critical deposition values (KDW) for nitrogen has serious shortcomings, according to the American statistician Matt Briggs and the Dutch researcher Jaap Hanekamp. This is reported by the Agrifacts Foundation (Staff).
Briggs and Hanekamp collected the underlying literature on the basis of which the CDWs were calculated for the different habitat types. The research is not carried out on behalf of Staf, but is partly financed by the foundation. "The critical deposition values – how much nitrogen a certain type of nature can tolerate without the risk of wasting away – are in fact the cork on which nitrogen legislation floats. Many critical deposition values were determined decades ago and have remained unchanged since then," explains Staf.
Multiplication indiscriminately
The organization highlights 3 imperfections. The KDW model is built on 19 measurements. According to the researchers, this is not enough to run the model, so 90 fictitious measurements have been added. Secondly, the KDW model would arrive at impossible results. "When there is no nitrogen deposition at all (background deposition of 0), the KDW model calculates a 20% chance that nitrogen has a harmful effect on nature."
Finally, the study shows that the scarce field trials that exist were conducted on plots of one square meter. "These are then indiscriminately multiplied by 10.000 to arrive at moles per hectare."
The researchers' first findings have been published online.
Linda van Eekeres
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