ABSTRACT Humans need food. Humans use energy. Production of food and combustion of fossil fuels increase concentrations of reactive nitrogen in the atmosphere, soils, and surface and ground waters of the Earth. These increases are caused in part by agricultural practices aimed primarily at increasing food production: the use of synthetic nitrogen fertilizers, widespread planting of N-fixing legumes, increased demand for animal protein in human diets, and increased use of fossil fuels. The world's crops, forests, and fisheries respond to reactive nitrogen (defined in the body of this article) enrichment with some positive benefits (such as increased food, feed, timber, and fish production) and some negative consequences (including acidification and eutrophication of aquatic and terrestrial ecosystems, decreased biodiversity, increased regional haze, global warming, and such human health impacts as nitrate contamination of drinking water and increased pulmonary and cardiac disease caused by exposure to toxic ozone and fine particulate matter).
So far, most pollution abatement strategies have aimed at resolving one or another air or water pollution problem in which various oxidized, reduced, and organic forms of reactive nitrogen play an important part. The time has come to consider more fully integrated strategies by which reactive nitrogen management practices can be optimized to increase agricultural, forest, and fish production while decreasing nitrogen-induced soil, air, and water pollution.
Contemporary challenges and opportunities facing animal agriculture in the United States today include joining with the U.S. Environmental Protection Agency, animal industry, university, and other scientists and policy makers in making realistic assessments of actual positive and negative impacts of reactive nitrogen emissions and leaching from animal agriculture and developing practical (economic) guidelines and strategies for the following: a) improving nitrogen conversion efficiency in poultry, swine, beef/dairy, and fish production, b) minimizing reactive nitrogen losses from manures, c) conserving and reusing reactive nitrogen and other valuable nutrients in animal wastes, d) developing more cost-effective horizontally and vertically integrated systems of animal production and manure management through production and marketing of value-added products, and e) minimizing use of fossil fuels in agriculture.
Science and Policy Implications
Contemporary changes in animal agriculture are increasing the circulation of reactive nitrogen (Nr) in the environment, which creates some positive benefits for agriculture and forestry, while also causing negative impacts on air and water quality, human health, and ecosystems. In most ecosystems, the result of increased loads of Nr will be substantially the same whether Nr emissions occur as oxidized, reduced, or organic forms. Instead of dealing with different forms of Nr separately, the Total Reactive Nitrogen Approach is justified. The Concept of Optimum Nr Management for Society is also proposed. Implementation will require determination of deposition and emission ceilings for each type of land use. Alternatives by which to adjust Nr loadings then can be considered. This will facilitate decisions by which various sectors of society can adjust their emissions of total Nr, and so do their part toward achieving a preferable total Nr emissions load within a more sustainable society.Key Words: Air Pollution, Ammonia, Emission, Environmental Impact, Nitrogen Cycle, Nutrient Management, Water Pollution
© 2002 American Society of Animal Science. All rights reserved.
J. Anim. Sci. 80(E. Suppl. 2):E157-E167
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