LOCATION ARMELLS MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, calcareous, frigid Aridic Ustorthents
TYPICAL PEDON: Armells channery loam, grassland (colors are for dry soil unless otherwise noted).
A--0 to 4 inches; reddish brown (5YR 5/3) channery loam, dark reddish brown (5YR 3/3) moist; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; 30 percent channers; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (3 to 7 inches thick)
Bk1--4 to 18 inches; reddish brown (5YR 5/3) extremely channery loam, reddish brown (5YR 4/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine roots matted around rock fragments; many distinct lime coatings on lower surfaces of coarse fragments; 60 percent channers, 5 percent flagstone; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary.
Bk2--18 to 30 inches; reddish brown (2.5YR 5/4) extremely channery loam, yellowish red (2.5YR 4/6) moist; massive; soft, very friable, slightly sticky and slightly plastic; few very fine roots; common faint lime coatings on lower surfaces of coarse fragments; 60 percent channers, 5 percent flagstones; strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (The combined thickness of the Bk1 and Bk2 horizons is 18 to 53 inches.)
Bk3--30 to 60 inches; yellowish red (2.5YR 5/6) extremely channery loam, yellowish red (2.5YR 4/6) moist; massive; soft, very friable, slightly plastic; few very fine roots; common faint lime coatings on lower sides of coarse fragments; 60 percent channers, 5 percent flagstones; strongly effervescent; moderately alkaline (pH 8.4). (0 to 40 inches thick)
TYPE LOCATION: Rosebud County, Montana; 2,000 feet east and 120 feet south of NW corner of sec. 8, T. 4 S., R. 44 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 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 or higher.
Depth to Bk horizon - 3 to 7 inches.
The surface when mixed to a depth of 7 inches does not meet the requirements of a mollic epipedon.
A horizon - Hue: 2.5YR, 5YR or 7.5YR
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2, 3, or 4
Texture: loam or sandy loam
Clay content: 10 to 22 percent
Rock fragments: 15 to 45 percent--0 to 15 percent flagstones; 5 to 30 percent channers
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 7.4 to 8.4
Bk1, Bk2 horizons - Hue: 2.5YR, 5YR or 7.5YR
Value: 4, 5, 6, or 7 dry; 3, 4, or 5 moist
Chroma: 3, 4, 5, or 6
Texture: loam or fine sandy loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 80 percent--0 to 10 percent flagstones; 35 to 70 percent channers
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
Bk3 horizon - Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 3, 4, 5, or 6
Texture: loam or fine sandy loam
Clay content: 15 to 27 percent
Rock fragments: 35 to 80 percent--0 to 10 percent flagstones; 35 to 70 percent channers
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - hills, terrace risers.
Elevation - 2,200 to 4,200 feet.
Slope- 1 to 70 percent.
Parent material - alluvium or colluvium derived from baked sandstone and shale (scoria).
Climate - long cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 15 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 100 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Armells soils are used mainly for rangeland. Potential native vegetation is mainly bluebunch wheatgrass, western wheatgrass, needleandthread, little bluestem, sideoats grama, plains reedgrass, blue grama, and plains muhly.
DISTRIBUTION AND EXTENT: Armells soils are of moderate extent in southeastern Montana and northwestern Colorado.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Aspen-Gypsum Soil Survey area, Colorado, 1982.
REMARKS: Soil interpretations records: MT0259, MT0761. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (mixed) (A, Bk horizons); a horizon of secondary calcium carbonate accumulation from 4 to 60 inches (Bk1, Bk2, Bk3 horizons); a particle-size control section from 10 to 40 inches (Bk1, Bk2, part of Bk3 horizon). The Armells soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.