LOCATION SIEBEN MT
Established Series
Rev. DES-JJU-RJS
06/2011
SIEBEN SERIES
The Sieben series consists of very deep, well drained soils that formed in alluvium and colluvium derived from metamorphic and igneous rock. They are on dissected alluvial fans, fan remnants, stream terraces, hills and mountains. Slopes are 1 to 60 percent. Mean annual precipitation is about 12 inches, and the mean annual air temperature is about 43 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Calcidic Argiustolls
TYPICAL PEDON: Sieben gravelly loam, rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 5 inches; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate very thin platy structure parting to moderate very fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; 20 percent angular gravel; slightly acid (pH 6.2); clear smooth boundary.
A2--5 to 9 inches; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular and interstitial pores; 20 percent angular gravel; slightly acid (pH 6.2); clear smooth boundary. (combined thickness of A1, A2 horizons - 6 to 10 inches)
Bt1--9 to 17 inches; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 4/3) moist; moderate prismatic structure parting to moderate fine and medium subangular blocky; hard, friable, moderately sticky and moderately plastic; common very fine roots; many very fine tubular and interstitial pores; many distinct brown (10YR 5/3) clay films on faces of peds; 45 percent angular gravel; slightly acid (pH 6.4); gradual smooth boundary. (5 to 15 inches thick)
Bt2--17 to 21 inches; pale brown (10YR 6/3) extremely gravelly loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; few faint clay films on faces of peds and on coarse fragments; 55 percent angular gravel and 5 percent angular cobbles; few faint calcium carbonate casts on undersides of rock fragments; slightly alkaline (pH 7.8); gradual smooth boundary. (3 to 8 inches thick)
Bk1--21 to 30 inches; very pale brown (10YR 7/3) very gravelly loam, pale brown (10YR 6/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; 45 percent angular gravel and 10 percent angular cobbles; continuous distinct calcium carbonate casts on underside of rock fragments, and many fine seams and masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (5 to 15 inches thick)
Bk2--30 to 41 inches; very pale brown (10YR 7/3) extremely gravelly loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; 55 percent angular gravel and 20 percent angular cobbles; continuous calcium carbonate prominent on rock fragments, and calcium carbonate cemented sand and fine gravel on undersides of some rock fragments; violently effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (8 to 15 inches thick)
Bk3--41 to 60 inches; pale brown (10YR 6/3) extremely gravelly sandy loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; 60 percent angular gravel and 15 percent angular cobbles; continuous faint calcium carbonate casts on underside of rock fragments; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Lewis and Clark County, Montana; 1,900 feet south and 50 feet east of the northwest corner of sec. 15, T. 13N, R. 4W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 42 to 47 degrees F.
Soil moisture - moist in some or all parts in most years more than half the time from April through October; frozen during the winter months
Mollic epipedon thickness - 7 to 10 inches
Depth to calcic horizon - 15 to 25 inches
A1, A2 horizons
Hue: 10YR or 2.5Y; dry or moist
Chroma: 2 or 3; dry or moist
Texture: loam or clay loam
Clay content: 10 to 27 percent
Rock fragments: 10 to 60 percent--10 to 30 percent gravel, 0 to 20 percent cobbles, 0 to 10 percent stones
Reaction: pH 6.1 to 7.3
Bt1 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 4 to 6 dry; 3 or 4 moist
Chroma: 3 or 4; dry or moist
Texture: loam clay loam or sandy clay loam
Clay content: 25 to 35 percent
Rock fragments: 35 to 60 percent--35 to 50 percent gravel, 0 to 5 percent cobbles, 0 to 5 percent stones
Reaction: pH 6.6 to 7.8
Bt2 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 or 6 dry
Chroma: 3 or 4; dry or moist
Texture: loam or sandy loam
Clay content: 15 to 25 percent
Rock fragments: 40 to 70 percent--35 to 65 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.6 to 7.8
Bk1, Bk2 horizons
Hue: 10YR or 2.5Y; dry or moist
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 2 to 4; dry or moist
Texture: loam, sandy loam or coarse sandy loam
Clay content: 10 to 27 percent
Rock fragments: 45 to 80 percent--40 to 60 percent gravel, 5 to 20 percent cobbles
Calcium carbonate equivalent: 10 to 30 percent (less than 18 % clay where CaCO3 is less than 15 percent)
Reaction: pH 7.9 to 8.6
Bk3 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam or loam
Clay content: 5 to 15 percent
Rock fragments: 50 to 80 percent--45 to 60 percent gravel, 5 to 20 percent cobbles
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Circleville (UT) - are moderately deep to a lithic contact
Dacore (UT) - have an aridic soil moisture regime
Dullknife (WY) - are moderately deep to a lithic contact
Ipson (UT) - are dry in all parts of the moisture control section 75 to 90 days during the winter and spring
Nebies (MT) - depth to the base of the argillic is less than 10 inches
Uracca (CO) - dry in some or all parts in most years more than half the time from April through October
Widtsoe (UT) - have a lithologic discontinuity
GEOGRAPHIC SETTING:
Landform - dissected alluvial fans, fan remnants, stream terraces, hills and mountains
Elevation - 3,800 to 6400 feet
Slope - 1 to 60 percent
Parent material - alluvium and colluvium derived from metamorphic and igneous rock
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 10 to 14 inches
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 70 to 120 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability to 41 inches and moderately rapid permeability below.
USE AND VEGETATION: Sieben soils are used mainly for rangeland. Potential native vegetation is mainly bluebunch wheatgrass, western wheatgrass, prairie junegrass, Sandberg bluegrass, needleandthread, forbs and shrubs.
DISTRIBUTION AND EXTENT: Sieben soils are moderately extensive in central and southwestern Montana. MLRAs - 43B, 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Lewis and Clark County Area, Montana, 1991; proposed in Lewis and Clark County, Montana, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 9 inches (A1, A2 horizons)
Argillic horizon - from 9 to 21 inches (Bt1, Bt2 horizons)
Calcic horizon - from 21 to 60 inches (Bk1, Bk2, Bk3 horizons)
Particle-size control section - from 9 to 21 inches (Bt1 and Bt2 horizons)
Sieben soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.
ADDITIONAL DATA: Soil interpretations records - MT0383, MT0384.
National Cooperative Soil Survey
U.S.A.