Slurry — a mixture of animal faeces, urine and water — and silage liquor, a by-product of the process by which cut grass is compressed and fermented into silage, are polluting water sources.
One of the increasingly important sources of agricultural pollution is the animal waste produced by corporate farms--huge operations housing thousands of animals in assembly-line conditions. The concentration of livestock in factory farms leads to a buildup of animal waste in the areas where these livestock operations reside. In the majority of cases, the systems used to treat animal waste are inadequate. Waste is pumped into open air pits called "lagoons", and from there, liquid manure is sprayed onto fields for crop irrigation.
In the United States, North Carolina's hog population has grown faster than any state in the nation, swelling from 2.6 million to 10 million hogs since 1987. These animals produce 19 million tons of feces and urine a year, or over 50,000 tons every single day. The hogs are concentrated in the eastern coastal plain, an economically important and ecologically sensitive network of wetlands, rivers, and coastline. In June 1998 the State authorities introduced tough new legislation on hog farms to control the dangers caused by the waste products.