The trend towards fewer and larger livestock farms has heightened public concern about pollution. Over the past several years, environmental policy related to animal agriculture has focused on land application of manure, especially methods to stop or reverse soil phosphorus build-up, runoff, and the subsequent pollution of lakes, streams and other surface water bodies. Policy is now focusing on the reduction of air emissions from animal agriculture. For dairy operations, ammonia is by far the most important potential air pollutant. The adverse effects of agricultural ammonia emissions extend to regional, national and global scales (NRC, 2003). Under the federal Consolidated Emissions Reporting Rule, all states are required to report agricultural ammonia-nitrogen (NH3-N) gas emissions to the U.S. Environmental Protection Agency (EPA) by the end of 2004. The data EPA collects will be used in air quality regulations to control the air-borne particulates and haze that affect many regions of the country.