## 2 Materials and Methods
### Scientific Background of Data Requirement and Modules of AGEM-S
#### 2.2.3 Housing Module  
The ammonia released in the pig houses is derived from urine [45], so the factors that determine the distribution of urine on the floor greatly influence ammonia emission [46; 47; 48; 49], which is a complex physical and chemical process [50].  
Ammonia is released into the air from the floor, the contaminated animal body, the walls, and the manure pit; the main sources are the contaminated concrete floor, the slatted floor, and the liquid manure [51; 52]. Reducing ammonia emissions in the pig barn can be achieved on the basis of the following [1]: reducing the surface area of the slurry; frequently removing slurry from the pit; additional treatment; cooling the surface of the slurry; changing the physical/chemical properties of the slurry; using easily cleanable surfaces; purifying the exhaust air; reducing the internal temperature and ventilation rate; reducing the air flow over the surface of the slurry.  
In the case of litter-based housing systems, deep litter can affect the extent of ammonia emission rates in different ways: urine infiltrates deep into the litter, reducing the surface area in contact with the air, and the structured rough surface of deep litter reduces airflow directly above the emitting litter surface. Moreover, litter material promotes the biological transformation of N through the oxidation and immobilization of TAN [53]. The literature data express contradictory views on the extent of emissions from litter systems. Some authors found significantly higher ammonia emissions from fully slatted floors than from  
\begin{table}
\begin{tabular}{l c} \hline Dry matter content of the diet (\%) \\ \hline Number of dietary phases in the fattening period & (1–4) \\ \hline Crude protein content of the diets (\%) \\ \hline Daily feed intake (g) \\ \hline Crystalline amino acid supplements & \\  & Lysine \\  & Methionine \\  & Thereonine \\  & Trytophan \\ \hline Benzoic acid supplementation of the diets & yes/not \\ \hline \end{tabular}
\end{table}
Table 2: Input data of the nutrition module.  
deep litter with straw bedding [54; 55; 56]; in contrast, others reported that deep litter emits nearly twice as much ammonia as the slatted floor [57; 58].  
Within the housing module of the AGEM-S, the most typical litter- and slurry-based housing systems and techniques for Hungarian conditions were considered, according to the type of floor and the method of manure removal. Several technologies can be chosen, for which ERs were assigned according to [PERSON] [31]: outdoor; litter based housing with daily manure removal; deep litter housing; slurry based housing with fully slatted floor; slurry based housing with partly slatted floor; concrete floor with manure channel. If available on the farm, the model considers the applied NH\({}_{3}\) emission-reducing housing techniques with the CFs on the basis of the Options for Ammonia Mitigation [1].  
The basic unit of the housing module is the stable. The excretion of the indoor livestock, calculated in the feeding module by age categories, is allocated in the given housing environment of each stable using the following input data (Table 3). The effect of feeding benzoic acid is taken into account here. The module calculates how much ammonia is released from the manure indoors and/or outdoors and how much N remains in the manure/slurry storage on the basis of the ERs of the applied housing technology elements and CFs of the emission reduction practices. Continuous production is assumed, with a steady utilization of capacity in the functional stables.