You can get a good idea about your soil type by rubbing a moistened sample between two fingers. Soil tests will provide information on soil type. For information on taking a soil test, contact your local University Outreach and Extension centers, the Soil and Water Conservation District or local Natural Resource Conservation Service offices. Groundwater is the water below the surface of the earth that, from the water table down, saturates the spaces between soil particles, sand and gravel layers, or fills cracks in underlying bedrock. Soil particle size influences which pollutants are able to reach groundwater.
Some soils are better at trapping pollutants than others.
Clay soils, common in north Missouri, are made of tiny particles, so they slow the downward movement of water and sometimes impede water movement completely. Sandy soils, as found in the Missouri Bootheel and along large rivers, allow rapid water movement, and silty soils occupy the middle range. Soils made of large particles pose the greatest risk, because water seeps downward through them readily without filtering out or decomposing pollutants. The ideal soil is a mix of midsize particles to allow infiltration and tiny particles, like clay or organic matter, to slow water movement and filter pollutants. Soil type can also affect surface water contamination.