LOCATION COOERS MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Haplustepts
TYPICAL PEDON: Cooers loam, in grassland (colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; brown (7.5YR 5/4) loam, dark reddish brown (5YR 3/4) moist; moderate platy structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; neutral (pH 7.2); clear smooth boundary. (4 to 5 inches thick)
Bw--4 to 15 inches; reddish brown (5YR 5/4) loam, dark reddish brown (5YR 3/4) moist; weak medium prismatic structure parting to weak coarse subangular blocky; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine tubular pores; 5 percent channers; slightly alkaline (pH 7.6); clear smooth boundary. (6 to 16 inches thick)
Bk1--15 to 19 inches; light reddish brown (5YR 6/4) loam, reddish brown (5YR 4/4) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; many very fine tubular pores; 5 percent hard channers; disseminated lime; many faint coats of lime on channers; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 12 inches thick)
Bk2--19 to 38 inches; light brown (7.5YR 6/4) loam, reddish brown (5YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; common very fine pores; 10 percent hard channers; disseminated lime; continuous faint coats of lime of channers; strongly effervescent; strongly alkaline (pH 8.8); gradual smooth boundary. (8 to 25 inches thick)
BC--38 to 60 inches; light brown (7.5YR 6/4) channery loam, reddish brown (5YR 4/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; few fine and very fine roots; 20 percent hard channers; strongly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Rosebud County, Montana; 2,100 feet north and 2,500 feet east of the SW corner of sec. 23, T. 3 S., R. 44 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 Bk horizon - 10 to 21 inches.
A horizon - Hue: 2.5YR, 5YR, or 7.5YR
Value: 3 or 4 moist
Chroma: 3 or 4
Clay content: 18 to 25 percent
Rock fragments: 0 to 5 percent channers
Reaction: pH 6.6 to 8.4
Bw horizon - Hue: 2.5YR, 5YR, or 7.5YR
Value: 3 or 4 moist
Chroma: 4, 5, or 6
Clay content: 18 to 27 percent
Rock fragments: 0 to 15 percent hard channers
Reaction: pH 7.4 to 8.4
Bk1 horizon - Hue: 2.5YR, 5YR, or 7.5YR
Chroma: 3 or 4
Clay content: 18 to 27 percent
Rock fragments: 0 to 15 percent hard channers
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
Bk2 horizon - Hue: 2.5YR, 5YR, or 7.5YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 3, 4, or 6
Clay content: 18 to 27 percent
Rock fragments: 0 to 20 percent hard channers
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 9.0
BC horizon - Hue: 2.5YR, 5YR, or 7.5YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 3, 4, or 6
Texture: loam, sandy loam, fine sandy loam
Clay content: 10 to 25 percent
Rock fragments: 0 to 25 percent hard channers
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 7.9 to 9.0
COMPETING SERIES:
Delpoint (MT) - has a paralithic contact within a depth of 40 inches.
Spinekop (MT) - has hue yellower than 7.5YR; is stratified at depths of 18 to 45 inches.
Trudau (MT) - has hue yellower than 7.5YR; has a Bkz horizon at a depth of 30 inches.
Yamacall (T)(MT) - has hue of 10YR or yellower in the surface, cambic, and Bk horizons.
GEOGRAPHIC SETTING:
Landform - sedimentary plains; hills; alluvial fans.
Elevation - 2,900 to 4,500 feet.
Slope- 2 to 35 percent.
Parent material - colluvium and alluvium derived from baked hard sandstone (scoria) and shale.
Climate - cool with cold, dry winters; moist springs; warm summers.
Mean annual precipitation - 10 to 16 inches.
Mean annual air temperature - 42 to 45 degrees F.
Frost-free season - 105 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Cooers soils are used mainly as rangeland but a few areas are used for dryland small grain and hay. The potential native vegetation is bluebunch wheatgrass, western wheatgrass, needleandthread, little bluestem, some forbs, and shrubs.
DISTRIBUTION AND EXTENT: Cooers soils are moderately extensive in southeastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Rosebud County, Montana, 1985.
REMARKS: Soil interpretations record: MT0168, MT7043. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (A, part of Bw horizons); a cambic horizon from 4 to 15 inches (Bw horizon); accumulation of carbonates from 15 to 38 inches (Bk1, Bk2 horizons); and a particle-size control section from 10 to 40 inches (part of Bw, Bk1, Bk2, part of BC horizon). Cooers soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.
Classification changed from Borollic Camborthids to Aridic Ustochrepts.