Soils Classified (USDA System)

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Soils Classified (USDA System)

• Terminology
• a. class A group of individuals that are
  similar in selected properties.
• b. category A group of classes.
• c. hierarchical system A system having a number
  of categories differing in level of
  generalization, such that each class within a
  category is also a subclass of a class within any
  higher category.

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• Formative Elements Syllables used to designate
  classes Order through Great Group
• Formative elements for Orders are as follows
• Alfisols - alf Inceptisols - ept
• Andisols and Mollisols - oll
• Aridisols id Oxisols - ox
• Entisols ent Spodosols - od
• Gelisol el Ultisols - ult
• Histosols ist Vertisols - ert

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5. Soil Orders that occur in Florida Histosols
- Dominated by organic soil material Spodosols
- Have Spodic. May have Argillic Mollisol - Have
Mollic BS 50. May have Argillic Alfisols
- Have argillic and BS 35 in lower
part Ultisol - Have argillic and BS lt 35 in
lower part Inceptisol - Have Umbric or Histic
(in some cases Mollic) Entisol - Default.
Absence of most diagnostic horizons to 2 m
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6. Categories Nomenclature Examples
Examples of Entisol Great Groups

• Suborder
• Aquents
• (Wet Entisols)

• Great Groups
• Cryaquents - cold
• Fluvaquents - floodplain
• Hydraquents - water
• Psammaquents - sand
• Epiaquents - perched

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Examples of Entisol Great Groups

• Suborder
• Fluvents
• (Floodplain soils)

• Great Groups
• Torrifluvents - torrid
• (hot and dry)
• Tropofluvents - tropical
• (warm and humid)
• Udifluvents - humid
• (not dry in most years)
• Ustifluvents - semi-arid
• (between Udic-Aridic)
• Xerofluvents - semi-arid
• (Mediterranean climate)

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Examples of Entisol Great Groups

• Suborder
• Psamments
• (Sandy Soils)

• Great Groups
• Cryopsamments
• Quartzipsamments - Quartz
• Torripsamments
• Udipsamments
• Ustipsamments
• Xeropsamments

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Examples of Subgroups
4 3 2 1 Typic Fluvaquents
4 1 2 Typical Entisols
with aquic moisture regimes
3 that occur on floodplains.
1. Order 3. Great Group 2.
Suborder 4. Subgroup (the typical
concept of Fluvaquents
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Examples of Subgroups
4 3 2
1 Mollic Fluvaquents 1
2 Entisols with aquic moisture regimes that
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occur on floodplains and have thick,
4 dark surface layers. 1. Order
3. Great Group 2. Suborder 4.
Subgroup (intergrading toward a Mollisol)
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Examples of Subgroups
4 3
2 1 Aeric Fluvaquents 1
3 2 Entisols on floodplains with aquic
moisture regimes that are not so wet. They are
better 4 aerated in the upper part of the
soil profile. 1. Order 3. Great
Group 2. Suborder 4. Subgroup
(intergrading toward a more aerated subgroup)

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Aquic Soil Moisture Regimes

• Typic subgroup of an aquic suborder
• Typic ____aqu____
• wettest
• Aeric subgroup of an aquic suborder
• Aeric ____aqu____
• better aerated
• Aquic subgroup
• Aquic ___________
• driest

From Mausbach 1992
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Nature of Number
Differentiating Category of Taxa
Characteristics Family Many The Family
name consists of a series of descriptive
names that modify the subgroup
name. Note since the family name adds no
knowledge to our understanding of wet
soils the family level of soil classification
will not be discussed.
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Nature of Number
Differentiating Category of Taxa
Characteristics Series 17,000 May have
virtually the full range of properties that
is permitted in a family, but in one or more
properties the range is restricted. N
ote since the series name adds no knowledge
to our understanding of wet soils it the
series level of soil classification will not
be discussed.
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7. Practice
Typic Haplosaprists
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Typic Haplosaprists

• What does the taxonomic classification mean?
• Is it likely, not likely, or maybe hydric?
• Histosol dominated by sapric material (wet).
• Likely to be hydric. Large areas of this soil
  converted to crop land in south Florida.

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Aquic Paleudalfs
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Aquic Paleudalfs

• What does the taxonomic classification mean?
• Is it likely, not likely, or maybe hydric?
• Alfisol with aquic conditions moderately deep in
  profile.
• Likely to be nonhydric. Has water table in E
  horizon for brief periods during high rainfall.
  In an aquic subgroup.

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Aquic Quartzipsamments
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Aquic Quartzipsamments

• What does the taxonomic classification mean?
• Is it likely, not likely, or maybe hydric?
• Entisol that is sandy, dominated by quartz sand,
  with aquic conditions moderately deep in profile.
• Likely to be a nonhydric soil. In an aquic
  subgroup. Seasonal high water table at about 24
  inches.

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Typic Argiaquolls
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Typic Argiaquolls

• What does the taxonomic classification mean?
• Is it likely, not likely, or maybe hydric?
• Mollisol with aquic conditions near surface and
  accumulation of clay in subsoil.
• Likely to be hydric. Hydric soils commonly
  classify in an aquic suborder argi is double
  whammy (will explain).

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Aeric Alaquods
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Aeric Alaquods

• What does the taxonomic classification mean?
• Is it likely, not likely, or maybe hydric?
• Spodosol with aquic conditions near surface not
  quite as wet as typic subgroups.
• Maybe hydric. Typical Spodosol on flatwoods. In
  an aquic suborder.

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Class as Likely Hydric, Maybe Hydric, or Likely
Non-Hydric

• Typic Haplosaprists Terric Haplosaprists
• Lithic Cryofolists Aquic Paleudalfs
• Aquic Glossudalfs Typic Aquisalids
• Aquic Quartzipsamments Typic Humaquepts
• Typic Argiaquolls Argiaquic Argialbolls
• Aeric Calciaquolls Aeric Alaquods
• Typic Umbraquults Chromic Epiaquerts

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Answers According to Hurt

• Likely Hydric
• Typic Haplosaprists Terric Haplosaprists
• Typic Humaquepts Typic Umbraquults
• Typic Argiaquolls Typic Aquisalids
• Chromic Epiaquerts Argiaquic Argialbolls
• Maybe Hydric
• Aeric Calciaquolls Aeric Alaquods
• Likely Nonhydric
• Aquic Glossudalfs Aquic Paleudalfs
• Aquic Quartzipsamments Lithic Cryofolists

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Summary

• Likely Hydric Soils in the Albolls Suborder or
  soils with a formative element at the Suborder
  level of soil classification (Aqu, Fibr, Hist,
  and Sapr.), unless they have the formative
  element aeri at the suborder level and soils in
  the following Great Groups Aquisalids,
  Historthels, and Histoturbels.
• Maybe Hydric Soils with a a formative element at
  the Suborder level of soil classification (Aqu,
  Fibr, Hist, and Sapr.) and the formative element
  aeri at the suborder level and soils on flood
  plains such as Aquic Dystrochrepts, Aquic
  Eutrochrepts, and Aquic Udifluvents.
• Likely Nonhydric Soils with all other
  classifications including aqu at the Subgroup
  level of soil classification with some exceptions
  (note the three example given above).