LOCATION SHANE MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Vertic Paleustolls
TYPICAL PEDON: Shane silty clay loam, cultivated (colors are for dry soil unless otherwise noted).
Ap--0 to 7 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; strong fine granular structure; slightly hard, very friable, sticky and plastic; many fine and very fine roots; medium acid (pH 5.6); abrupt smooth boundary. (4 to 7 inches thick)
Bt1--7 to 12 inches; brown (10YR 5/3) clay, dark brown (10YR 3/3) moist; strong fine and medium subangular blocky structure; very hard, firm, very sticky and very plastic; many fine and very fine roots; few very fine tubular pores; many faint clay films on faces of peds; slightly acid (pH 6.1); clear wavy boundary.
Bt2--12 to 18 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; strong fine and medium subangular blocky structure; extremely hard, very firm, very sticky and very plastic; common fine and very fine roots; few very fine tubular pores; many faint clay films on faces of peds; mildly alkaline (pH 7.4); gradual wavy boundary. (Combined thickness of the Bt horizons is 9 to 20 inches.)
Bk--18 to 36 inches; grayish brown and yellowish brown (10YR 5/2 and 5/4) clay loam, dark gray to dark yellowish brown (10YR 4/1 to 4/6) moist; moderate medium platy structure; very hard, friable, sticky and plastic; few fine and very fine roots; common very fine tubular pores; many fine seams and soft masses of lime; violently effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (7 to 20 inches thick)
Cr--36 to 60 inches; gray and yellowish brown (10YR 5/1 and 5/4) semiconsolidated shale with thin lenses of sandstone, dark grayish brown and dark yellowish brown (10YR 4/2 and 4/4) moist; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Chouteau County, Montana; 500 feet north and 700 feet east of the SW corner of sec. 18, T. 20 N., R. 8 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 46 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 15 inches (may include the Bt1 horizon).
Control section - 45 to 60 percent clay.
Depth to paralithic contact - 20 to 40 inches.
Depth to Bk horizon - 13 to 26 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 moist
Texture: loam, clay loam, or silty clay loam
Clay content: 20 to 35 percent
Reaction: pH 5.6 to 7.3
Bt1 horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: clay or silty clay
Clay content: 45 to 60 percent
Reaction: pH 6.1 to 7.3
NOTES: some pedons have skeletans or silans coating the peds
Bt2 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3 matrix, may have relic mottles with chroma 1 through 6
Texture: clay or silty clay
Clay content: 45 to 60 percent
Reaction: pH 6.6 to 7.8
Bk horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 0 through 6
Texture: clay loam, clay, or silty clay
Clay content: 35 to 55 percent
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.8 to 8.4
COMPETING SERIES:
Coben (MT) - does not have a paralithic contact above a depth of 40 inches; has columnar structure in the Bt horizon.
Ekah (MT) - does not have a paralithic contact above a depth of 40 inches; has a Bt/E horizon and a calcic horizon.
Shaak (MT) - does not have a paralithic contact above a depth of 40 inches; has an E horizon and Bt/E horizon; has very gravelly textures below 24 to 50 inches.
GEOGRAPHIC SETTING:
Landform - sedimentary plains and hills.
Elevation - 3,000 to 5,000 feet.
Slope- 0 to 25 percent.
Parent material - residuum and colluvium from semiconsolidated shale which may have thin lenses of sandstone or limestone.
Climate - long, cold winters; moist springs; and dry summers.
Mean annual precipitation - 14 to 19 inches.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 90 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; very slow permeability.
USE AND VEGETATION: Shane soils are used for nonirrigated cropland and rangeland. The potential native vegetation is western wheatgrass, bluebunch wheatgrass, rough fescue, Idaho fescue, green needlegrass, and Columbia needlegrass.
DISTRIBUTION AND EXTENT: Shane soils are of moderate extent in southern and central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Carbon County Area, Montana, 1971. Type location moved from Cascade County to Chouteau County, Montana 1990.
REMARKS: Soil interpretations record: MT0125, MT0128. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 12 inches (Ap and Bt1 horizons); an argillic horizon from 7 to 18 inches with an abrupt textural increase (Bt1 and Bt2 horizons); accumulation of lime from 18 to 36 inches (Bk horizon); a paralithic contact at 36 inches (Cr horizon). Surface horizons may become cloddy when plowed and have evidence of bleached sand grains. Shane soils have a frigid temperature regime and an ustic moisture regime.
Additional Data: Laboratory data, S71MT-013-6; S89MT-015-701.