LOCATION ASHUELOT MT
Established Series
Rev. NRS-JCK
08/2013
ASHUELOT SERIES
The Ashuelot series consists of shallow, well drained soils formed in alluvium or colluvium. These soils are on fan remnants, alluvial fans, and stream terraces. Slopes are 0 to 15 percent. Mean annual precipitation is about 356 mm, and mean annual temperature is about 6 degrees C.
TAXONOMIC CLASS: Loamy, carbonatic, frigid, shallow Petrocalcic Calciustolls
TYPICAL PEDON: Ashuelot gravelly loam, native grass (Colors are for dry soil unless otherwise noted).
A--0 to 13 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine and very fine roots; 20 percent gravel, 5 percent cobbles; slightly alkaline (pH 7.6); clear smooth boundary. (10 to 18 cm thick)
ABk--13 to 33 cm; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; strong coarse angular blocky structure parting to moderate medium angular blocky; hard, firm, moderately sticky and moderately plastic; many fine and very fine roots; many very fine pores; finely disseminated carbonates and many prominent carbonate coats on rock fragments; 10 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (0 to 20 cm thick)
Bk--33 to 46 cm; light brownish gray (10YR 6/2) clay loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many fine and very fine roots; many very fine pores; many medium and coarse calcium carbonate masses in the matrix; 10 percent gravel, some weakly cemented with carbonates; violently effervescent; strongly alkaline (pH 8.6); abrupt wavy boundary. (10 to 20 cm thick)
Bkkm--46 to 58 cm; light gray (10YR 7/2) and light brownish gray (10YR 6/2) moist; calcium carbonate cemented sand and gravel; extremely hard; violently effervescent; strongly alkaline (pH 9.0); clear wavy boundary. (10 to 20 cm thick)
BCk--58 to 96 cm; light brownish gray (10YR 6/2) extremely gravelly loamy sand, grayish brown (10YR 5/2) moist; single grain; nonsticky and nonplastic; finely disseminated carbonates and many thick carbonate coats on rock fragments; 60 percent gravel and 15 percent cobbles; strongly effervescent; moderately alkaline (pH 8.4). (0 to 40 cm thick)
C--96 to 152 cm; light brownish gray (10YR 6/2) extremely gravelly loamy sand, grayish brown (10YR 5/2) moist; single grain; nonsticky and nonplastic; 60 percent gravel and 15 percent cobbles; strongly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Judith Basin County, Montana; 774 meters west of the northeast corner of section 17, T13N, R14E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 4.4 to 5.6 degrees C.
Mollic epipedon thickness - 18 to 36 cm
Depth to petrocalcic horizon - 25 to 50 cm
The petrocalcic is slightly fractured in some pedons.
A horizon
Hue: 10YR
Value: 4 or 5 dry, 2 or 3 moist
Texture: loam or clay loam
Chroma: 2 or 3
Clay content: 18 to 35 percent
Rock fragments: 5 to 35 percent--5 to 25 percent gravel; 0 to 20 percent cobbles
Reaction: pH 7.4 to 8.2
ABk horizon (where present)
Hue: 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 5 to 35 percent--5 to 35 percent gravel; 0 to 10 percent cobbles
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 8.0 to 8.4
Bk horizon
Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 5 to 35 percent--5 to 35 percent gravel; 0 to 10 percent cobbles
Calcium carbonate equivalent: 40 to 60 percent
Reaction: pH 8.2 to 8.6
Bkkm horizon
Hue: 10YR or 2.5Y
Value: 7 or 8 dry, 5 or 6 moist
Chroma: 2 or 3
Rupture resistance: strongly cemented to indurated
Calcium carbonate equivalent: 50 to 60 percent
Reaction: pH 8.2 to 9.0
BCk horizon (where present)
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: sandy loam, loamy sand or sand
Clay content: 0 to 10 percent
Rock fragments: 60 to 80 percent--50 to 70 percent gravel; 10 to 20 percent cobbles
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 8.0 to 8.4
C horizon
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: sandy loam, loamy sand or sand
Clay content: 0 to 10 percent
Rock fragments: 60 to 80 percent--50 to 70 percent gravel; 10 to 20 percent cobbles
Reaction: pH 7.4 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - fan remnants, alluvial fans, and stream terraces
Elevation - 1,341 to 1,800 meters
Slope - 0 to 15 percent
Parent material - alluvium or colluvium
Climate - long, cold winters and moist springs, warm summers
Mean annual precipitation - 305 to 483 mm
Mean annual air temperature - 3.9 to 6.7 degrees C
Frost-free period - 70 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability to 46 cm, very slow from 46 to 58 cm, and rapid permeability below.
USE AND VEGETATION: Ashuelot soils are used mainly for rangeland and dryland crops; some areas are used for native hay and pasture. Potential native vegetation is mainly rough fescue, bluebunch wheatgrass, Idaho fescue, needleandthread, and forbs.
DISTRIBUTION AND EXTENT: Ashuelot soils are of moderate extent in west-central Montana. MLRA 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Reconnaissance of Northern Plains of Montana, 1929.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to 33 cm (A and ABk horizons)
Petrocalcic horizon - from 46 to 58 cm (Bkkm horizon)
Particle-size control section - from 25 to 46 cm (part of the ABk and Bk horizons)
Ashuelot soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.