LOCATION BLACKSHEEP MTEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, calcareous, frigid, shallow Aridic Ustorthents
TYPICAL PEDON: Blacksheep fine sandy loam, in rangeland. (Colors are for dry soil unless otherwise noted)
A--0 to 6 inches; brown (10YR 5/3) fine sandy loam, brown (10YR 4/3) moist; weak medium granular structure; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; common very fine tubular pores; slightly alkaline (pH 7.4); clear smooth boundary. (3 to 6 inches thick)
Bk--6 to 16 inches; light gray (2.5Y 7/2) very fine sandy loam, grayish brown (2.5Y 5/2) moist; weak medium prismatic structure parting to weak fine subangular blocky; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; common very fine and few fine tubular pores; few medium masses of lime; violently effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (5 to 14 inches thick)
Cr--16 to 60 inches; light gray (10YR 7/2) semiconsolidated sandstone; strongly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Custer County, Montana; 1,500 feet north and 1,200 feet east of the SW corner of sec. 32, T. 2 N., R. 46 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 8 inches and the paralithic contact; 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.
A horizon - Hue: 2.5Y, 7.5YR or 10YR
Value: 5, 6 or 7 dry; 4 or 5 moist
Chroma: 2 to 4
Texture: fine sandy loam, sandy loam or very fine sandy loam
Clay content: 5 to 15 percent
Rock fragments: 0 to 35 percent; 0 to 15 percent cobbles, and 0 to 20 percent pebbles
Reaction: pH 7.4 to 8.4
Bk horizon - Hue: 2.5Y, 7.5YR or 10YR
Value: 5, 6 or 7 dry; 4 to 6 moist
Chroma: 2, 3 or 4
Texture: very fine sandy loam, fine sandy loam or sandy loam
Clay content: 5 to 18 percent
Rock fragments: 0 to 35 percent; 0 to 15 percent cobbles, and 0 to 20 percent pebbles
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES:
Cabbart (MT) - has more than 18 percent clay in the particle-size control section; formed in materials derived from silt and loam bedrock.
GEOGRAPHIC SETTING:
Landform - sedimentary plains, ridges, escarpments and hills.
Elevation - 2,000 to 6,200 feet.
Slope- 2 to 50 percent.
Parent material - residuum or colluvium from sandstone.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 16 inches.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 95 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Cabbart soils on similar landscape positions.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability. Runoff is very low to medium depending on slope.
USE AND VEGETATION: Blacksheep soils are used mainly for rangeland, with limited use as forest land. Potential native vegetation is mainly Wyoming big sagebrush, bluebunch wheatgrass, needleandthread, Sandberg bluegrass, Indian ricegrass, threadleaf sedge, and fringed sagewort. Forest vegetation is mainly ponderosa pine. Dense stands are mainly on north slopes but trees can occur on all aspects.
DISTRIBUTION AND EXTENT: Blacksheep soils are of large extent on the sedimentary uplands of eastern and central Montana, and northeastern Wyoming.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Hill County, Montana, 1994.
REMARKS: Soil interpretation record: MT1470, MT1612.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the soil surface of the soil to a depth of 7 inches (after mixing) (A and Bk horizon); horizon of calcium carbonate accumulation - the zone from 6 to 16 inches (Bk horizon); particle-size control section - the zone from 10 to 16 inches (Bk horizon); paralithic contact of sandstone - at 16 inches (Cr horizon).