|Keeney, Dennis - IOWA STATE UNIVERSITY|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: November 2, 2000
Publication Date: N/A
Technical Abstract: Nitrogen (N) along with carbon is the most complex and crucial of the elements essential for life. Supplementing grain and grass forage crops with organic and inorganic fertilizers has long been recognized as a key to improving crop yields and economic returns. Nitrogen is the most widely utilized plant nutrient in fertilizers and is a major component of animal manures. Nitrogen compounds also have been recognized for their many potential adverse impacts on the environment and health. Many ecological problems occur when N is separated from its most common partner, carbon. Nitrification, denitrification, nitrous oxide formation, leaching of nitrate, and volatilization of ammonia are fates of the "mobile" N atom. Effects within the environment vary with the N form. The atmosphere might receive more nitrous oxide than it can assimilate, resulting in stratospheric ozone destruction. Combined N in the atmosphere and precipitation fertilizes natural ecosystems resulting in lowered biodiversity, stress, and N leakage, while acidity from nitric oxide and ammonia oxidation depletes ecosystems of bases and results in acid lakes and declining health of forests. The "solutions" to the issues on environmental effects of N will involve looking beyond the edge effects to redesigning agriculture in ways that will "tighten up" the N cycle and that will provide for N sinks such as grasslands and wetlands. To do this, policies will need to be developed that assure farmers and the public that such measures will not cost productivity, and that a redesigned agriculture can provide for future food needs. Turning back is not possible. The road ahead will demand a level of innovation of agricultural research and development of new agriculture systems.