A volatile discourse – reviewing aspects of ammonia emissions, models and atmospheric concentrations in The Netherlands

Abstract

In the Netherlands, there is a vigorous debate on ammonia emissions, atmospheric concentrations and deposition between stakeholders and research institutions. In this article, we scrutinise some aspects of the ammonia discourse. In particular, we want to improve the understanding of the methodology for handling experimentally determined ammonia emissions. We show that uncertainty in published results is substantial. This uncertainty is under-or even unreported, and as a result, data in national emission inventories are overconfident by a wide margin. Next, we demonstrate that the statistical handling of data on atmospheric ammonia concentrations to produce national yearly atmospheric averages is oversimplified and consequently atmospheric concentrations are substantially overestimated. Finally, we show that the much-discussed 'ammonia gap'either the discrepancy between calculated and measured atmospheric ammonia concentrations or the difference observed between estimated NH 3 emission levels and those indicated by atmospheric measurementsis an expression of the widespread overconfidence placed in atmospheric modelling.

Nitrate leaching from liquid cattle manure compared to synthetic fertilizer applied to grassland or silage maize in the Netherlands

“…A reduction in nitrate leaching due to higher ammonia volatilization is however to be regarded as a negative trade-off. Huijsmans et al (2016) reports an average volatilization loss of 16% of NH4-N for injected LCM versus 74% for surface-spread LCM, but it should be noted that there is ongoing debate on the reliability of ammonia measurements and reported volatilization levels (Hanekamp et al 2017). Because injection of LCM is under most circumstances mandatory in the Netherlands, this study focusses on the comparison between shallowly injected LCM and (surface-spread) CAN.…”

Accounting for uncertainties in ammonia emission from manure applied to grassland

“…Consequently, the confidence intervals in Table of Hanekamp et al . () are much too wide. Appendix provides a simple theoretical example using samples from the normal distribution to illustrate this concept.…”

“…An R script which implements the calculations of Hanekamp et al . () for the eight 2011 data sets is provided as Appendix .…”

“…In a recent critical study, Hanekamp et al . (,b) raised doubts about the emission reduction achieved in the Netherlands using low‐emission techniques, such as narrow band and shallow injection. Their study fuelled a long‐lasting debate (e.g.…”

“…This paper evaluates the method of Hanekamp et al . () for calculating measurement uncertainties of the percentage of applied ammonia emitted. It is shown here that their method is fundamentally flawed.…”