LOCATION CHIVINGTON              WY+MT

Established Series
Rev. AS/MCS/EMM
07/2012

CHIVINGTON SERIES

The Chivington series consists of very deep, well drained soils that formed in alluvium and colluvium from sedimentary rock. These soils occur on alluvial fans, fan remnants, terraces, landslides and foothills. Slopes range from 0 to 6 percent. Mean annual precipitation is about 16 inches and mean annual temperature is about 44 degrees F.

TAXONOMIC CLASS: Fine, smectitic, frigid Pachic Paleustolls

TYPICAL PEDON: Chivington loam - on a 2 percent east-facing slope utilized as rangeland. (Colors are for dry soil unless otherwise stated)

A--0 to 3 inches; dark brown (10YR 3/3) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; slightly alkaline (pH 7.8); clear smooth boundary. (2 to 10 inches thick)

Bt1--3 to 14 inches; dark brown (10YR 3/3) clay, very dark grayish brown (10YR 3/2) moist; strong coarse prismatic structure; hard, firm, sticky and plastic; common prominent clay films on faces of peds; many fine and very fine roots; slightly alkaline (pH 7.8); clear smooth boundary.

Bt2--14 to 29 inches; brown (10YR 4/3) clay, very dark grayish brown (10YR 3/2) moist; coarse angular blocky structure; very hard, firm, sticky and plastic; common prominent clay films on faces of peds; few very fine roots; slightly alkaline (pH 7.8); clear wavy boundary. (combined thickness of Bt horizons is 15 to 40 inches)

Bk1--29 to 33 inches; light yellowish brown (10YR 6/4) clay, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; violent effervescence; calcium carbonate as threads and seams; moderately alkaline (pH 8.4); clear smooth boundary.

Bk2--33 to 60 inches; light yellowish brown (10YR 6/4) clay, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, sticky and plastic; violent effervescence; calcium carbonate as soft masses, seams and threads; moderately alkaline (pH 8.4)

TYPE LOCATION: Laramie County, Wyoming. 2200 feet south and 150 feet west of the northheast corner of section 18, T 15 N, R 69 W. 41 degrees 05 minutes 12 seconds north latitude and 105 degrees 05 minutes 43 seconds west longitude.

RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon - 20 to 40 inches thick
Depth to secondary carbonates - 15 to 35 inches.
These soils are moist in April, May, and early June.

A horizon
Value - 3 or 4 dry
Chroma - 2 or 3
Texture - loam or silt loam
Clay content - 15 to 27 percent
Rock fragments - 0 to 5 percent gravel
Reaction - 6.6 to 7.8

Bt horizon
Value - 3 or 4 dry
Chroma - 2 or 3
Textures - usually clay but includes clay loam
Clay content - 35 to 60 percent
Rock fragments - 0 to 5 percent gravel
Reaction - 6.6 to 7.8

Bk horizon
Value - 5 to 7 dry, 4 to 6 moist
Chroma - 3 or 4
Textures - loam, sandy clay loam, clay loam, or clay
Rock fragments content - 0 to 25 percent gravel
Calcium carbonate equivalent - 5 to 15 percent
Reaction - 7.4 to 8.4

COMPETING SERIES:
Fughes (CO) - does not have horizons of secondary carbonate accumulation.
Hillery (NM) - does not have horizons of secondary carbonate accumulation.
Kubler (CO) - has hues of 5YR to 10R in the Bt horizons.
Lomapedro (NM) - does not have horizons of secondary carbonate accumulation.
Luna (AZ) - does not have horizons of secondary carbonate accumulation.
Zeeland (ND) - has redoximorphic features between 40 and 60 inches.
Zoltay (CO) - has hues of 7.5YR to 5Y

GEOGRAPHIC SETTING:
Landform - hill toeslopes and basin floors
Elevation - 5300 to 7500 feet
Slopes - 0 to 35 percent
Mean annual air temperature - 40 to 45 degrees F
Mean annual precipitation ranges - 15 to 19 inches
Frost free period - 80 to 110 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Poposhia and the Trimad soils. The Poposhia soil is lighter in color and has less than 35 percent clay in the profile. The Trimad soil has a diagnostic calcic horizon with more than 35 percent gravel content.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow. Slow permeability.

USE AND VEGETATION: The Chivington soils are used mostly as rangeland. The native vegetation is mostly Western wheatgrass, Green needlegress, Blue grama, and Winterfat.

DISTRIBUTION AND EXTENT: Southern Wyoming and central Montana. This series is of small extent. MLRAs 34A, 43B, and 46.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED: Laramie County, Western Part, 1991.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - 0 to 29 inches (A and Bt1 horizons)
Argillic horizon - 3 to 29 inches (Bt1 and Bt2 horizons)
Particle-size control section - 3 to 23 inches (Bt1 and part of the Bt2 horizon).

SIR - WY1298

The 7/2012 update reflects a reclassification from Argiustolls to Paleustolls.

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National Cooperative Soil Survey
U.S.A.