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Figuur 4. De resultaten van de experimenten met diverse mesttoedieningstechnieken op grasland in de periode 1989-2003.
Source publication
De focus van onderliggend onderzoek ligt op ammoniakemissies bij bemesting en op trends in atmosfeer- concentraties. Daartoe hebben we van de Wageningen University & Research (WUR) enkele meetreeksen van bemestingsproeven ontvangen (overigens zonder vermelding van spreiding van meetdata en meetonzekerheid) tezamen met het rekenmodel om die metingen...
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Water and public health
Dissertação de mestrado em saúde pública/ufc
Citations
... Thus, the widely reported dividing lines between emissions from different manure application techniques are likely blurred'. In addition, Hanekamp et al. (2017b) noted that the large uncertainties imply that 'claims such as '74% of the ammonia is released when manure is applied by means of surface broadcast spreading' are not only irresponsible but also incorrect'. These are serious comments that are addressed in this study by revisiting ammonia emission data obtained in 199 experiments conducted in the Netherlands, as reported by Huijsmans & Schils (2009). ...
... Due to the large number of experiments, especially for surface broadcast spreading and shallow injection, the 95% intervals are not very wide. This implies that, again on average, the conclusion of Huijsmans & Schils (2009) that '74% of the ammonia is released when manure is applied by means of surface broadcast spreading', which was criticized by Hanekamp et al. (2017b), is supported by the analysis in this paper. Moreover, differences between the three application methods are very significant with P-values smaller than 0.001. ...
A recent study has raised doubts about the ammonia emission reduction achieved in the Netherlands when applying manure to grassland by means of low-emission techniques such as narrow band and shallow injection. The critics claim that percentages of ammonia released to the atmosphere associated with low-emission techniques might even overlap with that from surface broadcast spreading given the large alleged experimental uncertainties in measurements. Consequently, the rationale behind the regulations to which farmers are exposed is questioned. In this study, it is shown that the alleged large uncertainties were obtained by means of an erroneous statistical method and that the real uncertainties are much smaller. It is also shown that, even when there is a large uncertainty in individual measurements, previous conclusions about differences in emission between different manure application techniques are still valid. It is further argued in this study that uncertainty in the percentage of applied ammonia emitted is implicitly taken into account in any comparative statistical analysis conducted in the past.
