If it ain’t anything else, it’s an… If it ain’t anything else, it’s an…

EntisolEntisolRebecca FranklinRebecca Franklin

SWES 541SWES 541

What is an Entisol?

• Soils of recent origin• Central concepts:

– soils developed in unconsolidated parent material – usually no genetic horizons except an A horizon– All soils that do not fit into one of the other 11 orders are Entisols– Characterized by great diversity in environmental setting and

land use.

• Many Entisols are found in steep, rocky settings. • Also, Entisols of large river valleys and associated

shore deposits provide cropland and habitat for millions of people worldwide.

What is an Entisol? continued

• weakly-developed soils• lack of strong development often due to one of

several factors: – persistent high water table – parent material composed mainly of quartz sand– location on an eroding slope– location on a very young landscape– are extremely young because recently disturbed by

human activity

Environmental conditionsconducive to Entisol formation

• Climate • Vegetation • Relief• Parent Material• Time

Entisol Processes and Properties

•Environment can inhibit soil forming processes

•Waterlogged•Sparse vegetation

•Compactness of rock

•May be in equilibrium with environment

•Ochric epipedon

•Albic horizon

•Maybe some fragmented diagnostic horizons

When you look at an Entisol you see…

• No commonly observed diagnostic horizons or properties.

• Some representative horizon sequences? Yes.

C

Bw

A

Bs

C

A

C

A

Accumulation of sesquioxides of Fe and Al

Development of color/structure; little or no accumulation of illuvial materials (Bw not cambic due to being too sandy)

Where in the world do you find Entisols?

• Entisols = ~17.9% of the Earth's ice-free land area, the largest percentage of any of the soil orders

Concentration of Entisols in U.S.

SUBORDERS

• Aquents - Entisols with a water table at or near the surface for much of the year

• Arents - Entisols that have been disturbed and contain fragments of diagnostic horizons that are not arranged in any discernable order

• Psamments - very sandy Entisols

• Fluvents - alluvial Entisols commonly found on floodplains

• Orthents - common Entisols that don't meet criteria of other suborders

What type of Entisols are in the United States?

% Wld %US Use Natural fertility

Psamments 3.14 2.81 Crops, Range

Low

Fluvents 2.2 1.7 Crops Moderate

Aquents <0.01 1.4 Wetlands, Crops

Moderate

Orthents 10.58 5.93 Forest, Range, Crops

Low to Moderate

For what do we use Entisols?

Fluvents• Recent water-deposited

sediments on:– Flood plains– Fans– Deltas along rivers or small

streams • Fluvents are frequently

flooded, unless protected by dams or levees

• Stratification of materials normal.

• Fluvent use:– Rangeland– Forest– Pasture– Wildlife habitat– Cropland

Udifluvent in east-central Louisiana

SW Wisconsin

Psamment• Psamments widespread, mainly:

– Nebraska– California– Minnesota– Wisconsin– Michigan– Arizona– Florida.

• Sandy in all layers- among the most productive rangeland soils in some arid and semiarid climates.

• Psamments that are nearly bare subject to soil blowing and drifting (bad driving).

• Psamments use:– Rangeland– Pasture– Wildlife habitat

Typic Psamment(in glacial outwash too sandy to be cambic, slight accum. of sesquioxides)

Xeric Psamment (in eolian sand)

AquentsPermentantly or usually wet soils

formed on river banks, tidal mudflats etc.

General wetness limits development.

Dominate some of the delineations along southern Atlantic, gulf coasts, flood plains along Mississippi River, and along other rivers and streams.

Some Aquents are forming in sandy deposits, mostly in recent sediments. They support vegetation that tolerates permanent or periodic wetness.

Use:PastureCroplandForestWildlife habitat.

Example from an athletic field: sandy fill material (anthrotransported deposits) placed over buried hydric soils

Arents• Mixed horizons, not permanently saturated with

water• Exhibit fragments of diagnostic horizons below

the Ap (plowed/disturbed layer) horizon• Deeply disturbed by farming, mining, or

construction. • Also termed anthropogenic soils: diagnostic

horizons cannot develop because of continued deep mixing through plowing, spading, or other methods of moving by humans.

Orthents• Very shallow soils• Completely devoid of weatherable

minerals• Found on recent erosional

surfaces or very old landforms• Lack horizon development due to

either steep slopes or parent materials that contain no permanent weatherable minerals (i.e. ironstone)

• Orthents are exceedingly shallow soils, referred to as "skeletal soils" or Lithosols

• Any former soil either completely removed or so truncated so diagnostic horizons typical of all orders other than Entisols are absent

• Orthent use: – Rangeland– Pasture– Wildlife habitat

To review…

• Summary: – Vegetation: not specified, bare soil – Climate: pergelic to hypothermic – Soil moisture regime: dry to aquic – Major soil property: featureless soil bodies – Diagnostic horizons: typically absent, albic (horizon

free from clay and iron oxides)– Epipedon: ochric – Characteristic: little or no evidence of soil

development