Explore Idaho Soils

 Healthy soil  is the foundation of life. It gives us clean air and water, bountiful crops and forests, productive grazing lands, diverse wildlife, and beautiful landscapes. Soil does all this by performing five essential functions:

• Sustaining plant and animal life - The diversity and productivity of living things depends on soil.
• Regulating water - Soil helps control where rain, snow melt, and irrigation water goes. Water and dissolved solutes flow over the land or into and through the soil.
• Filtering and buffering potential pollutants - The minerals and microbes in soil are responsible for filtering, buffering, degrading, immobilizing, and detoxifying organic and inorganic materials, including industrial and municipal by-products and atmospheric deposits.
• Cycling nutrients - Carbon, nitrogen, phosphorus, and many other nutrients are stored, transformed, and cycled in the soil.
• Physical stability and support - Soil structure provides a medium for plant roots. Soils also provide support for human structures and protection for archaeological treasures.

Soil health recognizes soil as a living, dynamic body capable of sustainably providing vital ecosystem functions for plants, animals, and humans. 

In the process of photosynthesis plants utilize water, sunlight, and carbon dioxide from the atmosphere to produce simple sugars and other carbon-based materials. Some of these come out through the plant roots and are utilized by the microbes in the soil. In return, the microbes help cycle important nutrients into the soil and back to the plant.

Tour Directions: taxonomic designations link to official soil series descriptions, soil location markers and maps are interactive. For any soil of interest, more detailed information is arranged by series, in alphabetical order, in the tour section. The escape key will bring you out of an interactive or zoom feature. Dig in! 

 Very-fine, smectitic, mesic Chromic Haploxererts 

Prominent Characteristic: clayey soil (vertisol)

Vertisols - These soils have markers of processes related to the failure of soil materials along shear planes (slickensides). Because the soil material moves, the diagnostic properties have many accessory properties. Among them are a high bulk density when the soils are dry, low or very low hydraulic conductivity when the soils are moist, an appreciable rise and fall of the soil surface as the soils become moist and then dry, and rapid drying as a result of open cracks. The unique properties common to Vertisols are a high content of clay, pronounced changes in volume with changes in moisture, cracks that open and close periodically, and evidence of soil movement in the form of slickensides and of wedge-shaped structural aggregates that are tilted at an angle from the horizontal. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Ashy, glassy, mesic Vitrandic Haploxerepts 

Prominent Characteristics: apparent coarse fragments which easily break down; weakly developed subsoil; highly erodible volcanic ash surface soil.

 Ashy over loamy-skeletal, aniso, glassy over isotic, frigid Typic Vitrixerands 

Prominent Characteristic: lithologic discontinuity. This soil has loamy material in the upper part that developed from the loess cap (with volcanic ash) over glacial outwash that created the gravel and sand substratum. The Missoula floods (last one ~13,000 years ago) is responsible for depositing the outwash material in this area. The coarse soil was subsequently blanketed with ash from the eruption of Mt. Mazama (~6,700 years ago).

 Fine, smectitic, mesic Abruptic Xeric Argidurids 

Prominent Characteristics: light surface, well developed subsoil, and a duripan.

A duripan (L. durus, hard; meaning hardpan) is a subsurface horizon that is cemented by illuvial silica to the degree that less than 50 percent of the volume of air-dry fragments slake in water or during prolonged soaking in acid (HCl). Duripans vary in the degree of cementation by silica. In addition, they commonly contain accessory cements, chiefly calcium carbonate. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Loamy, mixed, superactive, mesic, shallow Xeric Argidurids 

Prominent Characteristics: shallow to a duripan, moderately deep to bedrock.

 Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Calcic Argixerolls 

Prominent Characteristic: gravel and sand substratum.

 Loamy-skeletal, mixed, superactive, nonacid, mesic Lithic Xerorthents 

Prominent Characteristic: shallow to bedrock.

This soil is horizonated A over R, with a mere 4 inch thick surface horizon.

Coarse-silty, mixed, superactive, calcareous, mesic Typic Torriorthents

Prominent Characteristics: light colored surface and no other significant development in the subsoil.

Little development is why we see the A over C horizon designations.

 Fine, smectitic, mesic Vertic Paleargids 

Prominent Characteristics: light colored surface, well developed subsoil, lime accumulation deep in the profile.

This soil has 3 different parent materials the surface formed from recent alluvium, the mid-profile from loess, and the basalt residuum had little soil development at the very bottom.

 Fine-silty, mixed, superactive Alfic Argicryolls 

Prominent Characteristic: E horizon below the surface.

 Loamy-skeletal, mixed, superactive, mesic Lithic Argixerolls 

Prominent Characteristics: skeletal (>35% rock fragments), well developed subsoil (argillic), shallow to bedrock.

An argillic horizon is normally a subsurface horizon with a significantly higher percentage of phyllosilicate clay than the overlying soil material (photo 13). It shows evidence of clay illuviation. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Loamy-skeletal, carbonatic, frigid Lithic Haploxerolls 

Prominent Characteristics: cambic horizon and shallow to bedrock.

The bedrock of this soil is limestone so there is lime present throughout the profile. This lime presence can be confirmed with a weak hydrochloric acid field test, varying amounts of effervescence (bubbling) should be seen throughout.

 Loamy-skeletal, isotic, frigid Vitrandic Argixerolls 

Prominent Characteristics: skeletal (>35% rock fragments)

The sub-angular shape of the rock fragments are due to the relatively short distance the rocks have rolled down the canyon due to gravity. Contrast these to well rounded rock fragments worked by water often over great distances and seen in soils with alluvium parent material.

 Loamy-skeletal, mixed, superactive, frigid Ultic Argixerolls 

Prominent Characteristics: skeletal (>35% rock fragments)

These rock fragments became rounded while being naturally tumbled by water over great distances.

 Fine, smectitic, frigid Vertic Haploxerepts 

Prominent Characteristics: clayey soil; wide cracks to the surface when dry; stones on the surface; very slow permeability.

 Loamy-skeletal, mixed, superactive Typic Humicryepts 

Prominent Characteristic: skeletal (>35% rock fragments).

This soil occurs on glacial moraines. A glacier formed nearby Payette Lake by deepening an existing valley and dropping rocky debris that created a dam.

 Coarse-silty, mixed, superactive, mesic Xeric Haplodurids 

Prominent Characteristics: light colored surface and a duripan.

 Medial, amorphic, frigid Typic Vitrixerands 

Prominent Characteristics: volcanic ash surface and cinders in the substratum.

The source of volcanic cinders in this soil is from recent (~2,000 years ago) eruptions near Craters of the Moon National Monument. During eruptions larger particles like cinders would settle to the earth's surface first then finer ash over top.

 Fine, smectitic, mesic Xeric Argialbolls 

Prominent Characteristics: high organic matter in surface soil; E soil horizon below the surface soil; clayey subsoil with high shrink-swell.

 Coarse-loamy, mixed, superactive, frigid Pachic Haploxerolls 

Prominent Characteristics: thick (pachic), dark colored surface (mollic epipedon), soft bedrock (Cr horzon).

Pachic denotes a thick mollic epipedon (greater than 50 cm). (Soil Taxonomy. 1999. Ag Handbook 436.)

 Coarse-silty, mixed, superactive, mesic Xeric Haplocalcids 

Prominent Characteristics: lime accumulation deep in the profile and laminated sediments.

The platy structure clearly seen in the C horizon is due to the deposition of lacustrine material parallel to the surface in an ancient lake environment. These lakes were common landscape features in SW Idaho during the Pleistocene.

 Fine, smectitic, frigid Vertic Haploxerepts 

Prominent Characteristic: smectitic clays.

This soil contains a great amount of clay with high shrink swell potential. The prismatic structure clearly sen in the middle of this profile is often indicative of high clay content. Lake Bonneville located in modern day Salt Lake City, Utah is the source of lacustrine material in this soil. The Bonneville floods drained the much larger ancient lake to its much smaller current extent about 14,000 years ago.

 Fine-silty, mixed, superactive, mesic Pachic Ultic Haploxerolls 

Prominent Characteristics: thick (pachic), dark colored surface (mollic epipedon), very deep soil.

In this region the loess deposits can reach 100 feet thick. regionally glacial outwash provided the silty material source which was than picked up and subsequently deposited by strong winds from Washington to Idaho.

 Fine-loamy, mixed, superactive Pachic Haplocryolls 

Prominent Characteristic: Dark-colored surface (mollic epipedon).

The mollic epipedon is a relatively thick, dark colored, humus-rich surface horizon (or horizons) in which bivalent cations are dominant on the exchange complex and the grade of structure is weak to strong. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Fine, mixed, active, frigid Typic Hapludalfs 

Prominent Characteristic: E horizon (albic) at the surface.

The albic horizon is an eluvial horizon, 1.0 cm or more thick, that has 85 percent or more (by volume) albic materials. Albic (L. albus, white) materials are soil materials with a color that is largely determined by the color of primary sand and silt particles rather than by the color of their coatings. This definition implies that clay and/or free iron oxides have been removed from the materials or that the oxides have been segregated to such an extent that the color of the materials is largely determined by the color of the primary particles. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcids 

Prominent Characteristics: light colored surface, lime accumulation in the subsoil.

 Mixed Lamellic Cryopsamments 

Prominent Characteristics: coarse sandy textures and soft bedrock.

The bottom horizon is Cr which denotes a relatively soft bedrock that can be easily broken up unlike basalt.

 Euic, frigid Typic Haplosaprists 

Prominent Characteristic: high organic matter content.

The peaty textures and rich black color of the soil profile throughout are indicative of soil that developed in organic material versus the more common mineral soils. This is why the horizonation of this soil profile consists of a series of O horizons.

 Mixed, mesic Xeric Torripsamments 

Prominent Characteristics: sandy textures and no soil development in the subsurface.

The horizonation of this soil profile is simply C horizons.

 Coarse-silty, mixed, superactive, frigid Calcic Haploxerolls 

Prominent Characteristics: weakly developed subsoil, lime accumulation deep in the soil profile.

This profile is horizonated with an A at the surface over Bw (cambic horizons) over Bk horizons (lime accumulation).

A cambic horizon is the result of physical alterations, chemical transformations, or removals or of a combination of two or more of these processes. (Soil Taxonomy. 1999. Ag Handbook 436.)

  Sandy, mixed Humic Cryaquepts 

Prominent Characteristics: fluctuating water table; thick, very dark colored surface layer; sandy textures; acid reaction.

 Coarse-silty, mixed, superactive, frigid Vitrandic Fragixeralfs 

Prominent Feature: The lowest visible horizon is a fragipan.

A fragipan (modified from L. fragilis, brittle, and pan; meaning brittle pan) is an altered subsurface horizon, 15 cm or more thick, that restricts the entry of water and roots into the soil matrix. Commonly, it has a relatively low content of organic matter and a high bulk density relative to the horizons above it. The fragipan has a hard or harder rupture-resistance class when dry. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Fine-silty, mixed, superactive, mesic Xeric Natridurids 

Prominent Feature: E horizon at the surface, sodium in the subsurface, and a duripan.

Sodium is a deflocculant, meaning it makes particles disperse like clay. This leads to slow water permeability. This soil property at the surface can lead to the development of barren slick spots.

 Mixed, frigid Typic Xeropsamments 

Prominent Characteristics: no subsoil development; sandy textures; easily rippable bedrock; very low available water holding capacity.

 Fine-silty, mixed, superactive, mesic Oxyaquic Argixerolls 

Prominent Characteristics: E soil horizon below the surface soil; slow permeability.

 Loamy-skeletal, mixed, superactive, mesic Calcic Argixerolls 

Prominent Characteristics: skeletal (>35% rock fragments), clay accumulation (argillic), lime accumulation.

An argillic horizon is normally a subsurface horizon with a significantly higher percentage of phyllosilicate clay than the overlying soil material. It shows evidence of clay illuviation. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Loamy, mixed, superactive, mesic Lithic Xeric Haplocambids 

Prominent Characteristic: shallow to bedrock.

 Medial over loamy-skeletal, amorphic over isotic Vitric Haplocryands 

Prominent Characteristics: volcanic ash surface and skeletal control section (>35% rock fragments).

The weakly developed coarse textured soils in this area typically would have lower available water holding capacity (AWC). The reason this soil can support such lush vegetation and high yield trees is due to the andic properties in the surface attributed to volcanic ash content which significantly increases the AWC. The source of ash is multiple eruptions of volcanoes in the cascade range of Western Oregon and Washington. The greatest ash contributor is the famous eruption of Mt. Mazama (~6,700 years ago) which created the modern day Crater Lake.

Andic soil properties result mainly from the presence of significant amounts of allophane, imogolite, ferrihydrite, or aluminum-humus complexes in soils (photo 29). These materials, originally termed “amorphous” (but understood to contain allophane) in the 1975 edition of Soil Taxonomy, are commonly formed during the weathering of tephra and other parent materials with a significant content of volcanic glass. (Soil Taxonomy. 1999. Ag Handbook 436.)

 Fine-silty, mixed, superactive, frigid Cumulic Ultic Haploxerolls 

Prominent Characteristics: thick dark surface, gleyed colors and mottles in the subsoil.

This soil is horizonated with A-Ag-Bg-Cg. The mollic epipedon consists of the surface A horizons. The Bg and Cg horizons have a greyish tint to the soil and mottles due to a fluctuating water table.

Mottles are a type of redoximorphic feature, typically these blotches have a different color than the surrounding soil matrix.  Redoximorphic features associated with wetness result from alternating periods of reduction and oxidation of iron and manganese compounds in the soil.(Soil Taxonomy. 1999. Ag Handbook 436.)

The  Charles E. Kellogg Soil Survey Laboratory  (KSSL) is the key source for soil analytical data for the  National Cooperative Soil Survey (NCSS) . The KSSL receives samples from soil survey project offices located throughout the continental United States, Alaska, and Hawaii as well as from cooperating partners at universities and other government and non-government organizations.

***Find lab pedon ID numbers in the soils tour section within the landform maps when you click on the pit location points***

Query for soil data at the site below:

This story map brings a modern interface to many of the soil profiles found in the University of Idaho publication entitled "Idaho Soils Atlas" by  Raymond J. Barker ,  Robert E. McDole , and Glen H. Logan. University Press of Idaho, 1983. It is an excellent reference to add to your professional library.

Learn more about soils in your area. Just hit the big green button in the window below to get started.

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