The Impact of Animal Production Systems on the Nitrogen Cycle

The impact of animal production on the nitrogen cycle, and resulting causes for concern can be summarized by a sequential series of statements. - Nitrogen is in short supply All organisms require nitrogen for life, but natural sources do not provide enough nitrogen to grow plants and animals to sustain the world's population. - Human-created useable nitrogen can be used to grow plants and animals. The development of the Haber-Bosch process in the early 19th century was fundamental to society's ability to grow food. Without this additional source of nitrogen, 40% of the world¿s population would not be here today. - Most of the nitrogen added to fields or fed to an animal is lost to the environment. Plants and animals are inefficient in their uptake and incorporation of applied N. As a result, a large proportion of the N used to grow plants and animals is released to the environment. - Released nitrogen causes a cascading series of negative effects on ecosystems and humans. One atom of nitrogen released to the environment will contribute to most environmental issue of today, and can remain active in the environment for years to decades. - Industrial animal production systems (IAPS) are among the largest contributors of nitrogen to the environment. Large proportion of the N2O and NH3 emitted to the atmosphere are from IAPS. N2O contributes to global warming and stratospheric ozone depletion. NH3 enters the nitrogen cascade and can contribute photochemical smog, acid deposition, ecosystems fertilization, coastal eutrophication. In addition, much of the nitrogen lost to coastal ecosystems is from IAP systems. The nitrogen first contributes to eutrophication and then if converted to N2O will contribute to global warming and stratospheric ozone depletion. - There are regions (hotspots) where nitrogen losses to the environment from IAP systems dominate the nitrogen cycle. Atmospheric and riverine losses to the environment from IAP systems are especially pronounced in very large regions of Asia, in western Europe and smaller regions of North America, Latin America and Africa. - IAP systems result in large-scale transport of nitrogen exchange among continents due to international trade in fertilizer, feed and meat. With the significant growth of the international transport of N-containing commodities, nitrogen from one region can be transported thousands of kilometers, used for its purpose (e.g., fertilizer, feed) and then most is lost to the environment, contributing to the global impact of nitrogen. This paper expands on these statements by examining the role of industrialized animal production in contributing to the release of N to the Earth's atmosphere, biosphere and hydrosphere (on a spatially explicit global scale), the consequences of the losses, and presents a management model that will minimize the negative impacts, and enhance the benefits of nitrogen used for animal production.JRC.DDG.H.2-Climate chang