Using Soil Taxonomy Using Soil Taxonomy to Identify Potential to Identify Potential

Hydric SoilsHydric Soils

Soil Taxonomy

A basic system of soil classification for making and interpreting soil surveysObjective: To develop a hierarchical classification that

reflects the relationships between different soils, and between soils and the factors responsible for their character.

Soil Taxonomy

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

Series

Family

Sub Group

Great Group

Sub OrderFirst sign of wetness

Order12 Orders

Entisol

Fluvent

Ustic

Mollic

Fine-loamy, mixed, frigid

Korchea

Fine-loamy, mixed (calcareous), frigid,Mollic Ustifluvent (Korchea series, western ND)

Soil Taxonomy

Nature ofNumber Differentiating

Category of Taxa Characteristics

Order 12 Soil-forming processesas indicated by presenceor absence of majordiagnostic horizons

Soil Orders

• Inceptisols• Mollisols• Oxisols• Spodosols• Ultisols• Vertisols

• Alfisols• Andisols• Aridisols• Entisols• Gelisols• Histosols

Dominant Soil Orders

AlfisolsAndisolsAridisolsEntisolsGelisolsGel/Inc (AK)HistosolsInceptisolsMollisolsOxisolsSpodosolsUltisolsVertisols

Taxonomic NamesSoil OrderAlfisolAndisolAridisolEntisolGelisolHistosolInceptisolMollisolOxisolSpodosolUltisolVertisol

Name Ends in:-alf-and-id-ent-el-ist-ept-oll-ox-od-ult-ert

Entisol Suborders

• Aquents(L. Aqua, Water)Wet Entisols

• Fluvents(L. Fluvius, River)Floodplain Soils

• Orthents(Gr. Orthos, True)The Typical Ones

• Psamments(Gr. Psammos, Sand)Sandy Soils

Examples of Entisol Great Groups

• SuborderAquents(Wet Entisols)

• Great GroupsCryaquents - coldFluvaquents - floodplainHydraquents - waterPsammaquents - sandEpiaquents - perched

Examples of Entisol Great Groups

• SuborderFluvents(Floodplain

soils)

• Great GroupsTorrifluvents - 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)

Examples of Entisol Great Groups

• SuborderPsamments(Sandy Soils)

• Great GroupsCryopsammentsQuartzipsamments -

QuartzTorripsammentsUdipsammentsUstipsammentsXeropsamments

Interpreting Taxonomic Names

Subgroup - Great Group, Suborder, Order4 3 2 1

Vertic Udifluvent• 4 - Vertic subgroup - invert, shrink-swell, high clay• 3 - Udi(c) great group - humid climate• 2 - Fluv(ic) suborder - floodplain• 1 - Ent(isol) order - little soil development

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

Examples of Subgroups

4 3 2 1Typic Fluvaquents

4 1 2Typical Entisols with aquic moisture regimes

3that occur on floodplains.

1. Order 3. Great Group2. Suborder 4. Subgroup

Examples of Subgroups4 3 2 1

Mollic Fluvaquents

1 2Entisols with aquic moisture regimes that

3 occur on floodplains and have thick,

4dark surface layers.

1. Order 3. Great Group2. Suborder 4. Subgroup

Examples of Subgroups4 3 2 1

Aeric Fluvaquents

1 3 2Entisols on floodplains with aquic moisture

regimes that are not so wet. They are better4

aerated in the “upper” part of the soil profile.

1. Order 3. Great Group2. Suborder 4. Subgroup

Soil TaxonomyNature of

Number DifferentiatingCategory of Taxa Characteristics

Series 15,000+ May have virtually the full range ofproperties that is permitted in a family, but in one or more propertiesthe range is restricted, such as:- Kind and arrangement of horizons- Color- Texture- Structure

Typic Medisaprists

Typic Medisaprists

Terric Haplosaprists

Terric Haplosaprists

Lithic Cryofolists

Lithic Cryofolists

Aquic Paleudalfs

AquicPaleudalfs

Aquic Glossudalfs

AquicGlossudalfs

Typic Aquisalids

Typic Aquisalids

AquicQuartzipsamments

AquicQuartzipsamments

Typic Humaquepts

Typic Humaquepts

Typic Argiaquolls

Typic Argiaquolls

Argiaquic Argialbolls

Argiaquic Argialbolls

Aeric Calciaquolls

Aeric Calciaquolls

Aeric Alaquods

Aeric Alaquods

Typic Umbraqults

Typic Umbraqults

Chromic Epiaquerts

ChromicEpiaquerts