refers to the presence or absence either of ground water or of water held at a tension of less than 1500 kPa in the soil or in specific horizons during periods of the year.
Soil Moisture Regimes of the US
http://soils.usda.gov/use/thematic/moist_regimes.html The udic (L. udus, humid) moisture regime - soil is not dry in any part for as long as 90 cumulative days in normal years. The aquic (L. aqua, water) moisture regime - a reducing regime in a soil that is virtually free of dissolved oxygen because it is saturated by water.
A wetland soil (hydric soil) that, unless drained, is saturated with groundwater for long enough periods to develop a characteristic gleyic color pattern. This pattern is essentially made up of reddish, brownish or yellowish colours at surfaces of soil particles (peds) and/or in the upper soil horizons mixed with greyish/blueish colours inside the peds and/or deeper in the soil.
Soil Water Status
A consideration of multiple factors related to soil moisture; Drainage, Flooding, Ponding, Soil Moisture and Water Table
A soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part.
xeric or dry
The xeric moisture regime (Gr. xeros, dry) is the typical moisture regime of Mediterranean climates, where winters are moist and cool and summers are warm and dry.
A moderate or well-balanced supply of moisture, e.g., a mesic forest, a temperate hardwood forest, or dry-mesic prairie. Compared to a dry habitat, a mesic habitat is moister.
Soil Water State
Amount of Water currently in the soil Dry, Moist, Wet or Saturated
Soil Moisture - Tensiometer
measure kPa of vacuum on gauge. Large vacuum = drier soil.
Soil Moisture- Electrical Resistance
measure current through block. Large resistance = drier soil.