IATP Hog Report - Institute for Agriculture and Trade Policy

Section 4
IV. Part of the Pig
Really Does Fly
Sub-sections:
Odorous and Toxic
Emissions
Air Pollution Impacts on
Neighbors
Pollutants in Rain
Deposition
Greenhouse Gasses
Produced
Potential Solutions
Some Strategies and
Action Alternatives for
Clean Air from Animal
Production
References
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Part of the Pig Really Does Fly
Gasses emitted from liquid manure (slurry) lagoons and intensive
livestock confinement buildings are having detrimental effects, not only
on neighbors' quality of life, but also on their physical and mental health.
Ammonia released from the surface of liquid manure storage structures
also contributes to ammonia deposition in rainfall that can cause excessive
growth of algae in surface waters and the loss of aquatic life due to oxygen
depletion. Methane, carbon dioxide, and nitrous oxide are known to
contribute to global warming.
The problem results from the anaerobic (absence of free oxygen) nature of
manure that has been liquefied by the addition of water. 1 The
decomposition of liquid manure by anaerobic bacteria during storage and
treatment produces and emits nearly 400 volatile organic compounds. 2
Animal factories need not be large to create a problem. Prior to the mid-
1980s, most small, independent farmers raised their animals in bedded
shelters or barns with access to pastures and handled manure as a solid.
This practice caused few neighbor complaints and few environmental
problems. Increasingly, to save on labor and because it is the technology
recommended by the industry and agricultural advisors at land grant
universities, smaller farmers have adopted liquid manure handling
systems. These farmers also can create detrimental effects, albeit on a
more localized scale.
Odorous and Toxic Emissions
Compounds identified in liquid manure emissions include sulfides,
disulfides, organic acids, alcohols, aldehydes, amines, fixed gasses,
nitogen heterocycles, mercaptans, carbonyls, and esters. 3 Also identified
are carcinogens such as benzene 4 and the mutagen phosphane. 5 These
compounds also may be found in emissions from cattle and hog slurry
biogas processing plants. In addition to gasses, disease molecules can be
carried on the wind for miles, potentially affecting the health of animals
on other farms. 6
When manure is not liquefied and bedding is used, the soiled bedding is
stored in a solid form. Sufficient bedding creates a porous mixture wherein
free air space provides conditions suitable for aerobic microbes to
flourish. 7 Decomposition of solid manure by aerobic bacteria begins a
heating process called composting. 8 This decomposition process produces
heat, water vapor, carbon dioxide, and ammonia. Only ammonia is
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