Clay lined earthen manure storages are attractive alternatives for manure storage containers on an initial cost basis. As livestock facilities come under increased scrutiny, there will be an increasing need to demonstrate and document that the environment is protected. But be aware that soil material that is informally classified as clay may oftentimes be silt. Silt is not a good sealer to prevent liquid leakage from manure storages. A soil analysis by a qualified soils laboratory is the best way to distinguish silt from clay. However some "feel" methods can provide some clues. Wet clay soil will be sticky and will leave stains on your fingers. When pressed between thumb and forefinger, clay soils will form a long continuous ribbon. Silty soils will not. They may begin to form a

ribbon but will break apart in small pieces. Dry silty soils will have a floury or talcum-powder feel. During construction of an earthen manure storage, walk around and feel the soil to get some idea about whether the liner material is clay or silt. If there are any questions in your mind have the soil tested. Ask for an Atterberg test from soil engineers who have laboratory facilities. This test measures the moisture content at which soil demonstrates liquid properties and the moisture content where it loses its plastic characteristics (where a c of an inch cylinder will no longer stay together). The difference in moisture content is the "plastic index" (PI). NRCS standards suggest the PI should be above 10.

Howard Person