Re: What are the constituents of pig slurry (dung) ?
Date: Mon Mar 30 15:01:35 1998
Posted By: Bob Peeples, Chemical Engineer, Environmental Program Management, U S Postal Service
Area of science: Environment/Ecology
Agricultural activities (animal feeding and crop production) are
for the majority of surface water impairment in the United States. Animal
waste, if applied to land properly, can supply nutrients such as nitrogen
and phosphorus to soil. However, improper application of animal waste
or spills from lagoons can result in discharges into rivers and
streams that contribute to nutrient pollution of surface waters.
Overabundance of nutrients speeds the growth of algae in surface waters,
oxygen in the waters is depleted, and fish kills can result. Animal waste
also linked with pathogens such as cryptosporidium and giardia, that can
diseases in humans. You can easily see why it is
important to ensure that
animal waste is disposed of correctly.
I will assume that your question is only referring to a qualitative
Discharges from large scale concentrated animal feeding operations have
been regulated in the United States since 1976. In June 1995, heavy rains
caused an eight-acre lagoon in North Carolina to breach its dike, spilling
approximately 22 million gallons of animal waste into the New River. The
spill was twice the size of the Exxon Valdez oil spill, and reportedly
killed fish along a 19-mile downstream area. The US Environmental
Protection Agency (EPA) responded with a plan to reduce the possibility of
animal waste spills in the future. The Compliance Assurance
Implementation Plan For Concentrated Animal Feeding Operations can be
found on the EPA web site.
Sometimes it is easier to look on the surface for circumstantial evidence
such as pig
hair, ear tags, cigarette butts, or animal health products such as
hypodermic needle sheaths, etc. rather than the actual organic products of
porcine metabolism. Hogs (and farmers) tend to drop more than hog wastes
through the floor slats. Volunteer plants (such as a corn stalk in your
wheat field) might be evidence
of undigested or spilled swine food grains. Usually, the land application
is designed to pour or pump the slurry on to a spinning spreader rather
than spray it, so any small solid objects that pass through the pump end up
the field. As the liquid is absorbed within the soil, the solid material is
left sitting on the surface.
If you know what the hogs are being fed, it will make your job a lot
easier. This is especially true if unusual grains that show up as volunteer
plants, or if growth enhancing chemicals such as insecticides, hormones,
antibiotics, etc. are known to be used in the feeding regimen.
Isotope sampling tests are able to
differentiate between organic and inorganic nitrogen. From this test, you
can tell whether organic or chemical fertilizers were used as sources of
Microbial assessments may also
provide evidence, depending upon what you mean by "recent". Fecal coliform
bacteria, for instance, are readily identifiable and a good indication of
recent slurry application.
There is some discussion of the nature of livestock residues in Residue
Chemistry Test Guidelines, (7101) EPA 712-C-96-172 August 1996: OPPTS 860.1300, Nature of the
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