Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: November 2, 2007
Publication Date: July 20, 2008
Citation: Keeney, D.R., Hatfield, J.L. 2008. The nitrogen cycle, historical perspective, and current and potential future concerns. New York, NY: Academic Press. p. 1-18.
Nitrogen (N) along with carbon and oxygen are the most complex and crucial of the elements essential for life. Supplementing grain and grass forage crops with organic and inorganic N fertilizers has long been recognized as a key to improving crop yields and economic returns. Globally, N fertilizer is largely used for cereal grain production and accounts for an estimated 40% of the increase in per capita food production in the past 50 years. Nitrogen fertilizer supplies up to 40% of the world’s dietary protein and dependence on N from the Haber-Bosch process will increase in the future. Nitrogen compounds also have been recognized for their many potential adverse impacts on the environment and health. This review attempts to broaden the perspective on N in the environment beyond that of agriculture and crop production. The issues are major, and are recurring. Some are recycled and some are new, brought on by advances in science and monitoring that increased our awareness (e.g., hypoxia) and some are new because ecosystems are now showing stress that they were able to overcome earlier (global climate change, acid rain, ecosystem degradation). The issues may ebb and flow, but they will not go away. Society-wide spread dissemination of knowledge, open and informed discussion at world forums, and consensus on appropriate actions is called for. Technical solutions are the domain of the scientist, but such solutions must fit the world needs for a sustainable future.