LOCATION VASSETT                 WY SD

Established Series
Rev.JWW
06/2011

VASSETT SERIES

The Vassett series consists of deep and very deep, well drained, soils formed in alluvium from sedimentary sources. They are on relict fan aprons, fan remnants, and upland terraces. Slopes range from 0 to 10 percent. The mean annual precipitation is about 455 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Typic Argiustolls

TYPICAL PEDON: Vassett silt loam, on a northeast-facing slope of 2 percent, utilized as rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 23 cm; brown (7.5YR 4/2) silt loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly alkaline; clear smooth boundary. (10 to 23 cm thick).

Bt--23 to 61 cm; brown (7.5YR 5/3) silty clay loam, brown (7.5YR 4/3) moist; moderate coarse prismatic structure parting to strong fine angular blocky; hard, firm; many moderately thick clay films on faces of peds; moderately alkaline; clear smooth boundary. (30 to 41 cm thick).

Bk1--61 to 91 cm; brown (7.5YR 5/3) silt loam, brown (7.5YR 4/4) moist; moderate coarse subangular blocky structure; slightly hard, friable; violent effervescence, lime segregated as common fine masses, threads, and seams; strongly alkaline; clear smooth boundary.

Bk2--91 to 152 cm; light reddish brown (5YR 6/4) silt loam, yellowish red (5YR 4/6) moist; massive; slightly hard, very
friable; lime segregated as common fine masses, threads and seams; violent effervescence; strongly alkaline. (combined thickness of the Bk horizons is 50 to 105 cm)

TYPE LOCATION: Weston County, Wyoming; 7 miles west of Four Corners; about 850 feet south and 400 feet west of the center of Sec. 11, T. 47 N., R. 62 W.

RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon: 18 to 38 cm
Depth to calcium carbonate: 40 to 65 cm
Mean annual soil temperature: 5 to 8 degrees C

A horizon:
Hue: 2.5YR to 7.5YR
Value: 3 to 5, 2 or 3 moist
Chroma: 2 or 3
Texture: SIL or L
Clay: 15 to 27 percent
Reaction: Neutral or slightly alkaline

Bt horizon:
Hue: 2.5YR to 7.5YR
Value: 4 to 6, 3 to 5 moist
Chroma: 2 to 4
Texture: SIL, SICL, CL
Clay: 20 to 35 percent
Reaction: Slightly alkaline or moderately alkaline

Bk horizon:
Hue: 5YR or 7.5YR
Value: 4 to 6 dry, 4 or 5 moist
Chroma: 3 to 6
Texture: SIL, SICL
Clay: 15 to 30 percent
Calcium carbonate: 5 to 10 percent
Reaction: moderately alkaline or strongly alkaline

Some pedons have a C horizon

COMPETING SERIES:
Blackdog, Blackmore, Farland, Hanaker, Morton, Xavier- all have hues yellower than 7.5YR. Additionally, Blackdog and Blackmore soils formed in loess; Farland soils have stratified substratum; Hanaker soils formed in glaciolacusrine deposits; Morton soils are moderately deep to a paralithic contact; and Xavier soils have argillic horizons less than 15 cm thick.
Granath - has an argillic horizon that extends deeper than 100 cm and has a calcic horizon

GEOGRAPHIC SETTING:
Parent material: silty alluvium derived from mixed sources
Landform: relict fan aprons, fan remnants, and upland terraces
Landscape: foothills
Slopes: 0 to 10 percent
Elevation: 1,400 to 1,830 meters
Mean annual air temperature: 4.5 to 8 degrees C
Mean annual precipitation: 405 to 510 mm
Precipitation pattern: In most years, more than half of the annual precipitation occurs as snow and rain from April through July
Frost-free period: 80 to 110 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Colhill - have a loamy-skeletal particle-size control section; they occur above Vassett soils on the landscape
Colnevee - lack a mollic epipedon and argillic horizon; they occur on similar landscape positions as Vassett soils
The classification, specifically the SMR, of these associated soils is under review.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; slow to medium runoff; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Vassett soils are used for livestock grazing, hayland, and cropland. Native vegetation consists of western wheatgrass, green needlegrass, needleandthread, and blue grama. Alfalfa and winter wheat are grown in localized areas.

DISTRIBUTION AND EXTENT: Vassett soils occur on the Limestone Bench, High Precipitation and Red Valley, High Elevation physiographic areas of the Black Hills Foothills (MLRA 61), and on the Mixed Low Limestone Plateau physiographic area of the Black

Hills (MLRA 62). Northeastern Wyoming and extreme western and southwestern South Dakota. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED: Weston County, Wyoming; 1983.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 23 cm (A horizon)
Argillic horizon/particle-size control section: The zone from 23 to 61 cm (Bt horizon)
Other features: Common fine masses, threads, and seams of secondary calcium carbonate (Bk1 and Bk2 horizons)

Taxonomy version: Keys to Soil Taxonomy, Eleventh Edition (2010)

ADDITIONAL DATA:

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National Cooperative Soil Survey
U.S.A.