Re: What are the constituents of pig slurry (dung) ?

Agricultural activities (animal feeding and crop production) are responsible 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 is also linked with pathogens such as cryptosporidium and giardia, that can cause 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 assessment:

• 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 system 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 on 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 soil nitrogen.

• 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 Residue--Plants, Livestock