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About Hydric Soils

Lists of hydric soils are maintained for each soil survey area and may be obtained from the Field Office Technical Guide (FOTG) located in each NRCS field office.   You can locate the USDA Service Center that serves the county of interest at: http://offices.usda.gov/scripts/ndISAPI.dll/oip_public/USA_map.

What is a Hydric Soil?

"A hydric soil is 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." (Federal Register, July 13, 1994) A hydric soil is a soil that meets this definition.

What are Hydric Soil Criteria?

Hydric soil criteria are used to generate Hydric Soils Lists based on estimated soil properties. There are four types of criterion:

  • All Histosols except Folists
  • Soils that have a seasonally high water table during the growing season.
  • Soils that are frequently ponded for long or very long duration during the growing season.
  • Soils that are frequently flooded for long or very long duration during the growing season.

What are Hydric Soils Lists?

Hydric Soils Lists contain soils or soil map unit components that have a probability of being hydric. The Hydric status of a soil is an interpretation made by comparing its estimated soil properties with the Hydric Soil Criteria. A soil that is identified as hydric on a list must be confirmed in the field as meeting the Hydric Soil Definition through the use of hydric soil field indicators and/or best professional judgment.

What are Hydric Soil Field Indicators?

Hydric Soil Field Indicators are soil profile features used to identify and delineate hydric soils in the field. Presence and documentation of a field indicator confirms that a soil meets the Hydric definition. These field indicators are contained in the USDA-NRCS publication Field Indicators of Hydric Soils.

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Last Modified: 04/03/2006