LOCATION KILLPECKER              WY

Tentative Series
JSP-DPG-DEW
04/2025

KILLPECKER SERIES

Depth class: Very deep
Drainage class: Well drained
Saturated hydraulic conductivity class: Low
Parent material: Alluvium
Geomorphic location: Alluvial flats
Slope range: 0 to 3 percent
Mean annual temperature: 4.5 degrees C (40 degrees F)
Mean annual precipitation: 205 millimeters (8 inches)

TAXONOMIC CLASS:
Fine, smectitic, frigid Typic Haplosalids

TYPICAL PEDON: Killpecker loam in rangeland (Colors are for dry soil unless otherwise noted.)

A1--0 to 7 centimeters; light yellowish brown (2.5Y 6/3) loam, olive brown (2.5Y 4/3) moist; weak thin platy structure; slightly hard, friable, moderately sticky, moderately plastic; few very fine and fine roots throughout; few very fine vesicular pores; 1 percent fine distinct irregular salt masses in the matrix; very slightly effervescent; moderately alkaline, (pH 8.2); clear smooth boundary.

A2--7 to 16 centimeters; brown (10YR 5/3) clay loam, olive brown (2.5Y 4/3) moist; moderate medium granular structure; soft, very friable, moderately sticky, moderately plastic; common very fine and fine roots throughout; common very fine and fine vesicular pores; 1 percent fine distinct irregular salt masses in the matrix; slightly effervescent; strongly alkaline (pH 9.0); clear smooth boundary.

Bknz--16 to 33 centimeters; yellowish brown (10YR 5/4) clay, brown (10YR 4/3) moist; weak medium subangular blocky structure; moderately hard, firm, very sticky, very plastic; few very fine and fine roots throughout; few very fine and fine dendritic tubular pores; 5 percent fine distinct irregular calcium carbonate masses in the matrix; 5 percent fine distinct irregular salt masses in the matrix; slightly effervescent; strongly alkaline (pH 8.8); clear smooth boundary.

Btnz1--33 to 90 centimeters; brown (10YR 5/3) clay, olive brown (2.5Y 4/3) moist; moderate medium subangular blocky structure; moderately hard, firm, very sticky, very plastic; few very fine roots throughout; few fine dendritic tubular pores; 1 percent faint clay films on all faces of peds; 8 percent fine distinct irregular salt masses in the matrix; slightly effervescent; moderately alkaline (pH 8.4); clear smooth boundary.

Btnz2--90 to 115 centimeters; brown (10YR 5/3) clay, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, very firm, very sticky, very plastic; many very fine irregular pores; 1 percent faint clay films on all faces of peds; 12 percent fine distinct irregular salt masses in the matrix; slightly effervescent; moderately alkaline (pH 8.4); gradual smooth boundary.

BCnyz--115 to 200 centimeters; brown (10YR 5/3) clay, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; hard, very firm, very sticky, very plastic; many very fine irregular pores; 12 percent fine distinct irregular salt masses in the matrix; very slightly effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION:
Sweetwater County, WY
USGS Quadrangle: Boars Tusk SW
Latitude: 41.8383694
Longitude: -109.2076389
Datum: WGS84
Coordinates source: Hand-held GPS

RANGE IN CHARACTERISTICS:
Thickness of ochric epipedon: 4 to 17 centimeters
Depth to salic horizon: 0 to 33 centimeters
Particle-size control section (weighted average):
Clay content-35 to 60 percent
Sand content-8 to 37 percent
Total Rock Fragments-0 to 5 percent

A horizon(s)
Hue-10YR or 2.5Y
Value-4 to 7 dry; 3 to 5 moist
Chroma-3 to 5
Texture (less than 2 mm fraction) -loam, clay loam, silty clay, or silty clay loam
Clay content-20 to 43 percent
Sodium adsorption ratio-0 to 20
Electrical conductivity-1 to 50 dS/m
Reaction-pH 8.0 to 9.4
Thickness-4 to 17 centimeters

Bknz horizon(s)
Hue-10YR
Value-5 or 6 dry; 3 or 4 moist
Chroma-3 to 5
Texture (less than 2 mm fraction) -clay loam, clay, or sandy clay
Clay content-34 to 45 percent
Calcium carbonate equivalent-3 to 5 percent
Sodium adsorption ratio-27 to 35
Electrical conductivity-5 to 31 dS/m
Reaction-pH 8.6 to 9.2
Thickness-16 to 73 centimeters

Btnz horizon(s) (when present)
Hue-10YR or 2.5Y
Value-5 dry; 3 to 4 moist
Chroma-3 to 5
Texture (less than 2 mm fraction) -clay loam, clay or silty clay
Clay content-39 to 48 percent
Sodium adsorption ratio-8 to 15
Electrical conductivity-15 to 35 dS/m
Reaction-pH 8.2 to 8.8
Thickness-0 to 82 centimeters

BCnyz/BCk/CBk horizon(s) (when present)
Hue-10YR or 2.5Y
Value-5 or 6 dry; 3 or 4 moist
Chroma-3 to 5
Texture (less than 2 mm fraction) -clay, silty clay, or sandy clay loam
Clay content-28 to 54 percent
Sodium adsorption ratio-6 to 15
Electrical conductivity-24 to 40 dS/m
Reaction-pH 8.2 to 8.8
Thickness-0 to 45 centimeters

C horizon(s)
Hue-10YR or 2.5Y
Value-5 to 7 dry; 3 to 5 moist
Chroma-2 to 5
Texture (less than 2 mm fraction) -fine sandy loam, clay loam, clay, loam, or silt loam
Clay content-11 to 60 percent
Sodium adsorption ratio-8 to 20
Electrical conductivity-5 to 145 dS/m
Reaction-pH 8.4 to 8.8
Thickness-20 to 125 centimeters

COMPETING SERIES:
There are no competing series.

GEOGRAPHIC SETTING:
Parent material: Alluvium
Landform: Alluvial flats
Slope: 0 to 3 percent
Mean annual temperature range: 2.5 to 7.0 degrees C (37 to 45 degrees F)
Mean annual precipitation range: 180 to 230 mm (7 to 9 inches)
Frost-free period: 50 to 100 days
Elevation: 1,980 to 2,090 meters (6,496 to 6,857 feet)
Climate: Long, cold winters; cool, moist springs; short, warm summers

GEOGRAPHICALLY ASSOCIATED SOILS:
None listed.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: Well drained
Saturated Hydraulic conductivity: 0.01 to 0.5 m/sec

USE AND VEGETATION:
Killpecker soils are primarily used for rangeland. The potential native vegetation is mainly Indian ricegrass, western wheatgrass, greasewood, basin wildrye, Gardner's saltbush, and bottlebrush squirreltail.

DISTRIBUTION AND EXTENT:
Killpecker soils are of small extent in southwestern Wyoming. MLRA 34A.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED:
Sweetwater County, Wyoming, 2021. Killpecker series is derived from a local landmark.

REMARKS:
Typical Pedon Taxonomic Features:
Ochric epipedon-0 to 16 centimeters (A1 and A2 horizons)
Salic horizon-33 to 160 centimeters (Btnz1, Btnz2, and BCnyz horizons)
Sodic properties-16 to 160 centimeters (Bknz, Btnz1, Btnz2, and BCnyz horizons)
Particle-size control section: 25 to 100 centimeters
Taxonomic version: Keys to Soil Taxonomy, 13th edition (2022)

ADDITIONAL DATA:
Electrical Conductivity for this pedon is measured as 1:1 in the field and converted to saturated paste by ECs = (2.75 x EC 1:1) - 0.69 from Hogg, T.J. and J.L. Henry. 1984. Comparison of 1:1 suspensions and extracts with the saturation extract in estimating salinity in Saskatchewan soils.

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National Cooperative Soil Survey
U.S.A.