| RESEARCH METHODS
Water Quality
Although composting poses less of a threat to ground water than burial, emergency composting operations that are exposed to excessive rainfall can be expected produce contaminated liquid, known as leachate, that has potential to affect soil and shallow water quality beneath the composting area.
As illustrated above, excess liquid that causes leachate originates in two ways. Carcasses themselves release considerable water. One thousand pounds of cattle or swine carcasses contain about 750 pounds (90 gallons) of water. Leachate also is produced when precipitation percolates through the cover material and decaying carcasses.
Leachate can contain several potential water pollutants including: nitrogen; phosphorus; biochemical oxygen demand; organic acids; and chloride. Nitrogen and phosphorus are of greatest concern since they are released in the greatest quantities. Every 1000 lbs of cattle or swine carcasses contain about 22 pounds of nitrogen and 8 pounds of elemental phosphorus.
Leachate Quantity and Quality Representative samples of leachate produced by decaying carcasses and the various cover materials are captured by collection devices placed within the base layer of the composting test units. 
As shown here, the leachate collectors are simply half-sections of 6-inch diameter PVC pipe mounted on a treated lumber support.
The leachate collectors are slightly higher in the center of the pile than at the edges. This allows leachate to flow by gravity to plastic storage bottles at the toe of the test unit.
 The volume of leachate is recorded, and samples are analyzed in the laboratory for ammonia-nitrogen, chloride, and biochemical oxygen demand.
Soil Sampling Impacts of the composting process on soil and soil moisture quality are assessed by collecting four soil samples prior to construction of each test unit, and four samples after each test unit is dismantled.
Soil samples cores are collected using an electric impact hammer that drives a plastic-lined coring barrel into the top four feet of soil.
After removal, the soil cores are labeled and frozen until they can be tested for ammonia-nitrogen, nitrate-nitrogen, chloride, and total organic carbon.
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