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Curbing Livestock Emissions: ammonia, greenhouse gases, and odors
Author(s) -
Meadows Robin
Publication year - 2016
Publication title -
csa news
Language(s) - English
Resource type - Journals
eISSN - 2325-3584
pISSN - 1529-9163
DOI - 10.2134/csa2016-61-9-2
Subject(s) - livestock , greenhouse gas , ammonia , manure , environmental science , feedlot , nitrous oxide , manure management , nutrient pollution , agriculture , environmental chemistry , agronomy , chemistry , zoology , ecology , biology , organic chemistry
Livestock are a major source of ammonia, a nitrogen compound that contributes to the greenhouse gas nitrous oxide as well as to the fine airborne particles that threaten people’s health. Ammonia also harms the environment by acidifying soil and adding nitrogen to lakes, which boosts plant growth at the expense of animal life. In the U.S., agriculture accounts for more than 80% of ammonia emissions, which according to a 2016 PNAS study (www.pnas.org/ content/113/21/5874.full), have overtaken combustion from motor vehicles and industry as the dominant source of nitrogen pollution. Ammonia emissions rose 11% between 1990 and 2010 in the U.S., and the researchers cited livestock growth as one of the main causes. Ammonia emissions result from excess protein—which contains nitrogen— in livestock feed. Unused nitrogen is excreted in urine as urea, which a bacterial enzyme called urease then turns into ammonia. Cows excrete up to 90% of the nitrogen they eat while growing pigs excrete about 70%. But balanced diets— for example, those that supply adequate essential amino acids but not a protein overload—can cut nitrogen excretion by as much as 40%.