A process-based modeling approach was used to develop a comprehensive and predictive ammonia emission model for estimating ammonia emission rates from animal feeding operations. The ammonia emission model consists of farm emission model (FEM) and animal allocation processor (AAP) and can be used to calculate ammonia emission rates both from an individual AFO and from a group of AFOs and also allows predictions of different time scale resolutions. The Farm Emission Model (FEM) covers five animal species, including dairy, beef cattle, swine, layers, broilers, and turkeys. For each species, the FEM reflects different farm practices with regards to animal feeding, animal housing, manure collection and storage, and land application. The overall structure and selected model components of FEM are described in this paper. Some computer simulation results for a finishing swine farm are presented. The predicted ammonia emission rates are variable during the day and over the period of the year.This paper was presented at 14th International Emission Inventory Conference, 11–14 April 2005, Las Vegas, NV.</p
