LOCATION WESTPLAIN CO+WY
Established Series
Rev. AEA/RHM
12/2021
WESTPLAIN SERIES
The Westplain soils consist of deep, poorly to somewhat poorly permeable soils formed on polylithologic alluvial sediments consisting of relatively fine textured materials deposited over sand and gravel. These nearly level to gently sloping soils are on concave portions of alluvial fans and stream terraces. Slopes range from O to about 5 percent.
TAXONOMIC CLASS: Clayey over sandy or sandy-skeletal, mixed, superactive, mesic Aquic Haplustolls
TYPICAL PEDON: Westplain heavy clay loam - grassland. (Colors are for dry soil un/less otherwise noted.)
A1--0 to 8 inches; dark gray (10YR 4/1) heavy clay loam, dark gray (10YR 4/1) heavy clay loam, black (10YR 2/1) moist; moderate medium granular structure; soft, friable, sticky, plastic; calcareous; moderately alkaline; gradual wavy boundary. (6 to 10 inches thick)
A2--8 to 14 inches; dark gray (10YR 4/1) heavy clay loam, black (10YR 2/1) moist; weak medium subangular blocky structure that parts to moderate medium granules; hard, firm, sticky, plastic; calcareous; moderately alkaline; gradual wavy boundary. (6 to 10 inches thick)
AC--14 to 17 inches; brown (10YR 5/3) very gravelly clay loam, dark brown (10YR 3/3) moist; massive; hard, friable; common medium distinct strong brown (7.5YR 5/6) redoximorphic iron concretions; 50 percent gravel; calcareous; moderately alkaline; abrupt wavy boundary. (0 to 6 inches thick)
2Cg--17--60 inches; light gray (10YR 7/2) very gravelly sand, light brownish gray (10YR 6/2) moist; single grained; loose; many large prominent strong brown (7.5YR 5/6) redoximorphic iron concretions; 50 percent gravel; noncalcareous; moderately alkaline.
TYPE LOCATION: Logan County, Colorado; 72 feet north and 1,495 feet east of the west quarter corner of Sec. 7, T. 10 N., R. 48 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 50 degrees F.
Thickness of mollic epipedon: 12 to 26 inches
Depth to a contrasting C horizon: 12 to 26 inches
Particle-size control section (weighted average):
Clay content: 35 to 50 percent
Silt content: 15 to 40 percent
Sand content: 15 to 45 percent
Rock fragments upper few inches: 0 to 15 percent
Rock fragments lower and major portion: 35 to 80 percent
A horizon:
Hue: 2.5Y or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 or 2
Reaction: moderately alkaline
2C horizon:
Hue: 2.5Y or 10YR
Reaction: neutral or slightly alkaline
Note: in some pedons it is weakly and inconsistently calcareous.
COMPETING SERIES:
Currently there are no competing series
GEOGRAPHIC SETTING:
Parent Material: polylithologic alluvial sediments consisting of relatively fine textured materials deposited over sand and gravel
Landform: concave portions of alluvial fans and stream terraces
Slope: O to about 5 percent
Mean annual temperature: 47 degrees F.
Mean annual precipitation: 15 inches
Precipitation pattern: peak periods of precipitation in the spring and summer
GEOGRAPHICALLY ASSOCIATED SOILS:
These are the
Lebsack and
Nunn soils.
Both are well drained and are fine textured throughout their control section.
DRAINAGE AND PERMEABILITY:
Drainage: poorly to somewhat poorly drained
Runoff: low
Permeability slow above the very gravelly sand. These soils have fluctuating water tables that occur within the control section during some season of most years.
USE AND VEGETATION: These soils are used mainly as native pastureland and are tilled in some localities.
DISTRIBUTION AND EXTENT: Northeastern Colorado. The series is of moderate extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Salina, Kansas
SERIES ESTABLISHED: Logan County, Colorado, 1974.
REMARKS: OSED scanned by NSSQA and cleaned up by Colorado. Last revised by state 6/74.
Diagnostic horizons and features recognized in this profile are:
Mollic epipedon: 0 to 17 inches (A horizon)
Redoximorphic features: 14 to 60 inches (AC and 2C horizon)
Updated the classification, competing series and placed in semitab format. LRM 03/01
National Cooperative Soil Survey
U.S.A.