Soil Taxonomy
Using Soil Taxonomy
to Identify Potential
Hydric Soils
Soils are classified on the basis of:
• Soil properties observed in the field (e.g.,
soil horizons, texture, color, pH) and
• Soil properties inferred from the combined
data of soil science and other disciplines
(e.g., soil temperature and moisture regimes
inferred from soil science and
meteorology).
Soil Taxonomy
Order
12 Orders
Sub Order
First sign of wetness
Soil Orders
Entisol
•
•
•
•
•
•
Fluvent
Great Group
Ustic
Sub Group
Mollic
Family
Fine-loamy, mixed, frigid
Series
Korchea
Dominant Soil Orders
Alfisols
Andisols
Aridisols
Entisols
Gelisols
Histosols
•
•
•
•
•
•
Inceptisols
Mollisols
Oxisols
Spodosols
Ultisols
Vertisols
Taxonomic Names
Alfisols
Andisols
Aridisols
Entisols
Gelisols
Gel/Inc (AK)
Histosols
Inceptisols
Mollisols
Oxisols
Spodosols
Ultisols
Vertisols
Soil Order
Alfisol
Andisol
Aridisol
Entisol
Gelisol
Histosol
Inceptisol
Mollisol
Oxisol
Spodosol
Ultisol
Vertisol
Name Ends in:
-alf
-and
-id
-ent
-el
-ist
-ept
-oll
-ox
-od
-ult
-ert
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Entisol Suborders
• Aquents
• Orthents
(L. Aqua, Water)
Wet Entisols
• Fluvents
(Gr. Orthos, True)
The Typical Ones
Examples of Entisol Great Groups
• Suborder
Aquents
(Wet Entisols)
• Psamments
(L. Fluvius, River)
Floodplain Soils
(Gr. Psammos, Sand)
Sandy Soils
• Great Groups
Cryaquents - cold
Fluvaquents - floodplain
Hydraquents - water
Psammaquents - sand
Epiaquents - perched
Taxonomy’s “Problem” Soil
Orders
Oll
Mollisols
Dark colored surface layers "mask" redox features.
Check colors below mollic, allow surface layers to
dry then look for redox (NTCHS Indicator F6).
Od
Spodosols
Sandy surface layers, no redox features evident in
upper part. (Use organic layers, dark surface, and
stripped matrix indicators).
Alf
Alfisols
Gray / White (high value / low chroma) horizon
below A, not necessarily indicative of wetness.
Ent
Entisols
Recent depositions exceed rate of typical hydric
morphology formation. Many sands are Entisols.
Houghton Muck
Houghton Series
Hydric
Typic
Argiaquolls
Summary
• Interpretation of Soil Taxonomic names in
Soil Survey manuscripts provides another
tool for identifying hydric soils.
– Most useful off-site as part of preliminary
analysis
– Also useful to identify potential “problem”
hydric soils
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