Report - DCE - Nationalt Center for Miljø og Energi

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The emission of NH3 from manure management is calculated on the basis on
nitrogen excreted from livestock. Most of the N excreted that is readily degradable
and broken down to NH4-N is found in the urine. The relationship
between NH4-N and total N will not remain constant over time due to
changes in feed composition and feed use efficiency. In order to be able to
implement the effect of NH3-reducing measurements as improvements in
feed intake and composition in the emission inventory, it is necessary to calculate
the emission based on the Total Ammoniacal Nitrogen (TAN) content,
which has been done to the extent possible. From 2007 the calculation of
NH3 emission from liquid manure is based on TAN. For solid manure and
deep litter an emission factor for total N is still used.
The normative figures for both total nitrogen excretion and the content of
TAN are provided by Department of Animal Science, Aarhus University.
In Table 2C.1 is given the average N-excretion (TAN) for each NFR livestock
category from 1985 to 2010. These values includes N excretion from grassing
animals. Notice that each livestock category is an aggregated average of different
subcategories (see Table 6.3 in Chapter 6).