Proposed Method for Determining Ammonia Emission Factors from Confined Swine Feeding Operations

Using an average ammonia emission factor multiplied by number of pigs to determine a regional or national ammonia emission inventory may be misleading. Ammonia emissions from swine feeding operations depend on the housing type; animal size, age, and type; manure management, storage and treatment system; land application techniques or manure utilization method, and climatic variables. Typically, emission factors developed for swine facilities in Western Europe have been used to estimate emission factors in the U.S. Housing, manure management practices, and climate vary in different regions of the United States, and can be very different from Western Europe conditions. Also, various ammonia measurement methods and methods of determining ammonia emission or flux have been used, often making it difficult to compare results. To determine accurate ammonia emissions from confined swine feeding operations, it is important that emission factors unique to animal type and size, housing system, manure storage and treatment, and land application are used, as well as accounting for climatic effects. This paper describes the strengths and limitations of emission factors as currently used and provides recommendations for determining realistic ammonia emission factors for swine feeding operations. Because of the limited data published in the literature, examples of emission factors for different animal management systems were not calculated.