The vadose zone, also termed the unsaturated zone, is the portion of Earth between the land surface and the phreatic zone or zone of saturation ("vadose" is Latin for "shallow"). It extends from the top of the ground surface to the water table. Water in the vadose zone has a pressure head less than atmospheric pressure, and is retained by a combination of adhesion (funiculary groundwater), and capillary action (capillary groundwater). If the vadose zone envelops soil, the water contained therein is termed soil moisture.
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The zone between land surface and the water table within which the moisture content is less than saturation (except in the capillary fringe) and pressure is less than atmospheric. Soil pore space also typically contains air or other gases. The capillary fringe is included in the vadose zone. (See: Unsaturated Zone.)