LOCATION SPUDBAR MT
Established Series
Rev. GFB-JJU-RJS
06/2011
SPUDBAR SERIES
The Spudbar series consists of moderately deep, well drained soils that formed in colluvium or slope alluvium over residuum derived from mixed rock sources. These soils are on cuestas, hills and ridges. Slopes are 2 to 60 percent. Mean annual precipitation is about 12 inches, and mean annual air temperature is about 40 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Aridic Calciustolls
TYPICAL PEDON: Spudbar very cobbly loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 6 inches; brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine and few medium roots; many very fine interstitial pores; 20 percent gravel and 20 percent cobbles; finely disseminated calcium carbonate; slightly effervescent; slightly alkaline (pH 7.6); clear smooth boundary. (5 to 8 inches thick)
Bk1--6 to 18 inches; very pale brown (10YR 8/3) very gravelly loam, pale brown (10YR 6/3) moist; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; common fine interstitial pores; 40 percent gravel and 15 percent cobbles; many distinct calcium carbonate coats on rock fragments and common irregular fine masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (5 to 15 inches thick)
Bk2--18 to 22 inches; very pale brown (10YR 8/2) extremely gravelly sandy loam, pale brown (10YR 6/3) moist; weak fine granular structure; soft, very friable, slightly sticky and nonplastic; few very fine roots; few very fine interstitial pores; 60 percent gravel and 15 percent cobbles; many distinct calcium carbonate coats on rock fragments and common irregular masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (4 to 17 inches thick)
R--22 to 60 inches; slightly weathered igneous rock.
TYPE LOCATION: Beaverhead County, Montana; 1,700 feet north and 50 feet west of the southeast corner of sec. 5, T. 6S, R. 9W; Bond topographic quadrangle; Lat. 45 degrees 20 minutes 21 seconds N. and Long. 112 degrees 43 minutes 27 seconds W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 38 to 43 degrees F.
Soil moisture control section - 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 higher than 41 degrees F.
Mollic epipedon thickness - 7 to 8 inches
Depth to calcic horizon - 5 to 8 inches
Depth to lithic contact - 20 to 40 inches
A horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam, sandy loam or silt loam
Clay content: 10 to 25 percent
Rock fragments: 20 to 60 percent--20 to 35 percent gravel, 0 to 25 percent cobbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 6.6 to 7.9
Bk1 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 4; dry or moist
Texture: loam, sandy loam or silt loam
Clay content: 10 to 25 percent
Rock fragments: 25 to 60 percent--25 to 45 percent gravel, 0 to 20 percent cobbles
Calcium carbonate equivalent: 10 to 30 percent (less than 18 % clay where CaCO3 is less than 15 percent)
Reaction: pH 7.6 to 8.6
Bk2 horizon
Hue: 10YR, 2.5Y or 7.5YR; dry or moist
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 5; dry or moist
Texture: sandy loam, loam or silt loam
Clay content: 10 to 25 percent
Rock fragments: 35 to 80 percent--35 to 65 percent gravel, 0 to 15 percent cobbles
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.6 to 8.6
COMPETING SERIES:
Arle (CO) - are moderately deep to a paralithic contact
Guben (UT) - are very deep
Tricart (MT) - are very deep
Tridell (UT) - are very deep
Trimad (MT) - are very deep
Whetrock (UT) - are moderately deep to a paralithic contact
GEOGRAPHIC SETTING:
Landform - cuestas, hills, and ridges
Elevation - 5,000 to 6,500 feet
Slope - 2 to 60 percent
Parent material - colluvium or slope alluvium over residuum derived from mixed rock sources
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 10 to 14 inches
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 70 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Spudbar soils are used principally for rangeland. The native vegetation is mainly bluebunch wheatgrass, needleandthread, and big sagebrush.
DISTRIBUTION AND EXTENT: Spudbar soils are of small extent in southwestern Montana. MLRAs - 43B, 44B, 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Beaverhead County, Montana, 2001
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 7 inches mixed (A, part of Bk1 horizons)
Calcic horizon - from 6 to 22 inches (Bk1, Bk2 horizons)
Lithic contact - at 22 inches (R horizon)
Particle size control section from 10 to 22 inches (part of Bk1, Bk2 horizons)
Spudbar soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
National Cooperative Soil Survey
U.S.A.