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Proper Use of Hydric Soil Terminology

Proper Use of Hydric Soil Terminology. Objectives. Explain difference between hydric soils definition, criteria, field indicators, and technical standard. Define terms important to hydric soil identification. NTCHS. The National Committee for Hydric Soils is represented by 4 universities

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Proper Use of Hydric Soil Terminology

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  1. Proper Use of Hydric Soil Terminology

  2. Objectives • Explain difference between hydric soils definition, criteria, field indicators, and technical standard. • Define terms important to hydric soil identification.

  3. NTCHS • The National Committee for Hydric Soils is represented by • 4 universities • 6 NRCS • 1 representative from USFS, USACOE, USEPA, USFWS, and BLM • The NTCHS makes all decisions on hydric soils.

  4. Wetlands

  5. Wetlands • Wetlands are delineated for jurisdictional purposes using a 3 parameter approach. • Hydrophytic vegetation • Wetland hydrology • Hydric soils

  6. Definition, criteria, indicators and technical standard

  7. Hydric Soils

  8. Definition • “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”(59 Fed. Reg. 35680, 7/13/94)

  9. Definition • “that formed under” – hydrology alteration does not make a hydric soil no longer hydric • “develop anaerobic conditions” – lack oxygen, does not have to be reduced • “in the upper part” – generally 12.5 cm (5 in.) in a sandy soil and 25 cm (10 in.) in a fine textured soil

  10. CriteriaThe criteria for Hydric Soils (Fed. Reg., 2/29/2012) • All Histels except Folistels and Histosols except Folists • The “saturation” criteria • based on the range of characteristics for the soil series, will at least in part meet one or more Field Indicators of Hydric Soils in the United States, or • show evidence that the soil meets the definition of a hydric soil; • 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…

  11. Growing Season • The portion of the year when soil temperatures are above biological zero at 50 cm. Permafrost: • Hypergelic July – Aug. • Pergelic July – Aug. • Subgelic July – Aug.

  12. Criteria • Main purpose is to create hydric soil lists • Not all soils on list are hydric, • Range of characteristics may include both hydric and non-hydric soils • Hydric soil lists are an interpretative rating which must be confirmed by on-site investigations

  13. Criteria, cont. • Criteria are not intended for on-site application • Criteria 1 is an indicator • Data that proves criteria 3 or 4 exists can be used to document the presence of a hydric soil

  14. Hydric Soil Indicators • Indicators are not intended to replace or relieve the requirements contained in the Hydric Soil Definition • Indicators are used to identify the hydric soil component of wetlands; however, there are some hydric soils that lack one of the currently listed indicators

  15. Data Standard for Hydric SoilsRequirements • Water table measurements • Redox potential measurements • Reduced Iron (Fe II) measurements • In-situ pH measurements • On-site precipitation data • Replicates

  16. Summary • All hydric soils must meet the definition • Criteria are used to generate lists • Lists are used off-site to determine if an area is likely or not to contain hydric soils • Indicators are used to identify hydric soils on site • Technical standard is used with data • To prove a functional hydric soil exists in the absence of an indicator, and to develop new indicators

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