Sensitivity Analysis and Application of a Dynamic Simulation Model of Nitrogen Fluxes in Pig Housing and Outdoor Storage Facilities

This article presents the sensitivity analysis of a deterministic model proposed by Berthiaume et al. (2005) for the prediction of daily nitrogen concentrations Nconc in kg [N] t−1[slurry] and loads Nload in kg [N] inside buildings and storage facilities at the production site scale. This model makes use of many parameters and therefore, it is important to evaluate the impact of each of these. Identification of those parameters which most affect the output values allows for the rationalisation of resources when establishing a sampling protocol for determining more precise parameter values. The most important parameters identified were the proportion of proteins in feed P, the temperature of the slurry T, the pH of the slurry h, and, the air speed over slurry v. It therefore confirmed the already acknowledged high importance of feed content and methods of distribution—information that can be easily obtained from producers and, thus, can be used in the determination of regional amounts of nitrogen produced by swine production systems (e.g, municipality, county or watershed level). In addition, this sensitivity analysis confirmed that some characteristics that are seldom known to producers—slurry pH and air speed over slurry—are also of great importance. Finally, two sets of simulation scenarios were used to illustrate potential applications of this model as a management tool and to further demonstrate its coherent behaviour over different sets of parameter values.