Background

Under standard conditions, ammonia is a colorless gas with a pungent odor detectable at 3 to 5 parts per million but easily discernible at concentrations above 50 parts per million. It is ubiquitous in the soil, atmosphere, and waters of the earth with most of the ammonia coming from anthropogenic (human-related) activity. It is highly reactive and remains in the atmosphere only a short time. It reacts quickly with water, forming ammonium. In the air, it can dissolve in precipitation and fall to the earth as ammonium. Because ammonia gas is so reactive, after being released, its concentration is localized because of absorption by both plants and/or water and neutralization to aerosols. However, ammonia rarely is depleted in the atmosphere because all plants have a point below which they emit gaseous ammonia; at concentrations above this point (ammonia compensation point), plants will absorb ammonia.

The possible combined effect of ammonia absorption and ammonium aerosol deposition can be both beneficial and harmful. In fertilized cropping systems, the plant community may absorb significant quantities of nitrogen from the atmosphere. The release of ammonia into areas of natural terrestrial and aquatic ecosystems may cause a significant shift in the nutrient economy. This destabilizing effect in the existing plant community may result in replacement by species that use more nitrogen. Ecosystem soils may become more acidified, with possible long-term nutrient imbalances of calcium, potassium, and magnesium. Ammonia emissions also potentially cause some nitrous oxide loss into the atmosphere.

The largest source of ammonia emissions is the use of synthetic or biologically-fixed nitrogen (atmospheric nitrogen that has been incorporated into a nitrogen-containing compound by plants). The major global anthropogenic sources are from domestic and wild animal wastes (40%), fertilizer use (17%), oceans (8%), biomass burning (6%), agricultural crops (4%), humans and pets (3%), and natural ecosystems (3%). About half of the global emissions come from Asia, and about 70% of the total is related to food production. However, the regions with highest geographically-localized emission rates are found in Europe, the Indian subcontinent, China, and parts of the U.S. The largest potential concentrated sources are animal feeding operations because they often are located in relatively small geographical areas to provide increased efficiency, improved economics, and a better industry support system. These facilities use waste management systems that release ammonia to the environment.

The calculation of ammonia emissions from domestic animal production is based on an average nitrogen excretion for different categories. However, emissions can be quite different depending on housing types, feedstuffs and nutritional management systems, waste handling methods, application techniques, and type of crops upon which wastes are applied. Indeed, emission calculations do not take into account partial processing of the wastes during housing and/or waste storage (lagoons or holding tanks), assuming all nitrogen losses as atmospheric ammonia emissions and leaching into the soil from the storage liners. Data on domestic animal ammonia emissions in the U.S. are limited, and early ammonia emissions inventories were based on European country-specific emissions from animal wastes. Better emissions information is needed from U.S. production systems, which are very different from European conditions, including climatic, management systems, housing, and waste recycling and/or disposal systems. Furthermore, reduction of nitrogen losses is economically significant, providing strong motivation from the animal and crop producer=s viewpoint to promote reduction or prevention of these losses.

Vision

Productive animal and cropping systems that minimize ammonia-containing nitrogen emissions to the atmosphere

Mission

Develop systems to reduce ammonia emissions from cropping and animal production systems while improving productivity