Hydric Soils - Overview
The Hydric Soils section presents the most current information about hydric
soils. It updates information that was previously published in “Hydric Soils of
the United States” and coordinates it with information that has been
published in the “Federal Register”. It also includes the most
recent set of field indicators of hydric soils.
Four types of technical information about hydric soils are presented.
- The current definition of a hydric soil
— This definition
has been consistent in the
overall concept that hydric soils are those soils that are sufficiently
wet in the upper part to develop anaerobic conditions during the growing
- The database selection criteria for hydric soils and
the lists which are generated from them — The database selection criteria are selected soil
properties that are documented in Soil Taxonomy and were designed
primarily to generate a list of potentially hydric soils from soil survey databases.
Only criteria 1, 3, and 4 can be used in the field to determine hydric soils;
however, proof of anaerobic conditions must also be obtained for
criteria 1, 3, and 4 either through data or best professional
judgment (from Tech Note 1). The primary purpose of these selection criteria is to generate a list of soil
map unit components that
are likely to meet the hydric soil definition. Caution must be used when
comparing the list of hydric components to soil survey maps. Many of
the soils on the list have ranges in water table depths that allow the
soil component to range from hydric to nonhydric depending on the location
of the soil within the landscape as described in the map unit. Lists
of hydric soils along with soil survey maps are good off-site ancillary
tools to assist in wetland determinations, but they are not a substitute
for observations made during on-site investigations.
- The list of field indicators of hydric soils — The field indicators are morphological properties known to
be associated with soils that meet the definition of a hydric soil.
Presence of one or more field indicators suggests that the processes
associated with hydric soil formation have taken place on the site being
observed. The field indicators are essential for hydric soil
identification because once formed, they persist in the soil during both
wet and dry seasonal periods.
- The Hydric Soil Technical Notes — Contain National Technical Committee for Hydric Soils (NTCHS) updates,
insights, standards, and clarifications.
Next item — Introduction