LOCATION SPINEKOP MT+WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Haplustepts
TYPICAL PEDON: Spinekop silty clay loam, in irrigated cropland (colors are for dry soil unless otherwise noted).
Ap--0 to 11 inches; grayish brown (10YR 5/2) silty clay loam, dark grayish brown (10YR 4/2) moist; cloddy structure parting to weak fine and medium granular; hard, friable, sticky and plastic; common fine roots; slightly alkaline (pH 7.8); clear smooth boundary. (4 to 11 inches thick)
Bw--11 to 17 inches; grayish brown (10YR 5/2) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure parting to moderate medium angular blocky; hard, friable, sticky and plastic; common fine roots; many very fine tubular pores; slightly alkaline (pH 7.8); clear smooth boundary. (6 to 9 inches thick)
2Bk--17 to 21 inches; light yellowish brown (2.5Y 6/4) loam, light olive brown (2.5Y 5/4) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; many very fine tubular pores; disseminated lime, few very fine masses of lime; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 6 inches thick)
2BC--21 to 33 inches; pale brown (10YR 6/3) clay loam; light olive brown (2.5Y 5/4) moist; massive; hard, friable, sticky and plastic; few fine roots; many very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (8 to 20 inches thick)
2C1--33 to 43 inches; pale brown (10YR 6/3) loam consisting of thin layers of fine sandy loam and silty clay loam, light olive brown (2.5Y 5/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (5 to 25 inches thick)
2C2--43 to 60 inches; pale brown (10YR 6/3) loam consisting of thin layers of fine sandy loam and silty clay loam, light olive brown (2.5Y 5/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Rosebud County, Montana; 1,900 feet west and 2,200 feet north of the SE corner of sec. 21, T. 6 N., R. 39 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 44 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees F or higher.
Depth to stratified material - mainly 32 to 40 inches, but ranges from 18 to 45 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay loam, loam, sandy loam, fine sandy loam, or very fine sandy loam
Clay content: 15 to 40 percent
EC: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 8.4
Bw horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3 or 4
Texture: silty clay loam and clay loam
Clay content: 27 to 35 percent
EC: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 8.4
2Bk, 2BC horizons - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: loam, clay loam, or silty clay loam
Calcium carbonate equivalent: 5 to 15 percent
Clay content: 18 to 35 percent
EC: 0 to 4 mmhos/cm
Reaction: pH 7.4 to 8.4
2C horizons - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loam or clay loam consisting of thin layers of fine sandy loam or silty clay loam or both
Clay content: 18 to 30 percent
EC: 0 to 4 mmhos/cm
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Cooers (MT) - has hue of 7.5YR or redder throughout.
Delpoint (MT) - has a paralithic contact at depths of 20 to 40 inches.
Trudau (MT) - has a Bkz horizon of salt accumulation above a depth of 40 inches.
Yamacall (T)(MT) - does not have a discontinuity; is not stratified at depths above 40 inches.
GEOGRAPHIC SETTING:
Landform - stream terraces. (Foothills in Wyoming)
Elevation - 2,200 to 3,000 feet. (In Wyoming, greater than 6,000 feet)
Slope- 0 to 10 percent.
Parent material - calcareous alluvium.
Climate - long, cold, dry winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches, most of which fall during spring and the early part of summer. (In Wyoming, up to 16 inches)
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 105 to 135 days. (In Wyoming, 85 to 135 days)
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Spinekop soils are used mainly for irrigated crops. A few areas are used as rangeland. Potential native vegetation is bluebunch wheatgrass, green needlegrass, western wheatgrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: This series is of small extent in eastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Rosebud County, Montana, 1985.
REMARKS: Soil interpretation record: MT0646. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to a depth of 11 inches (Ap horizons); a cambic horizon from 11 to 17 inches (Bw horizon); an accumulation of lime from 17 to 21 inches (2Bk horizons); a particle-size control section from 10 to 40 inches (Ap, Bw, 2Bk, 2BC, 2C1 horizons). Spinekop soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.