LOCATION BARKOF MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Leptic Udic Haplusterts
TYPICAL PEDON: Barkof clay in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 7 inches; dark grayish brown (2.5Y 4/2) clay, dark grayish brown (2.5Y 4/2) moist; strong fine granular structure; very hard, very firm, moderately sticky and very plastic; a thin 1/8-inch surface crust forms when dry; many very fine roots; slightly effervescent; moderately alkaline; gradual boundary. (4 to 7 inches thick)
Bss--7 to 24 inches, grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to weak medium and coarse subangular blocky; very hard, very firm, moderately sticky and very plastic; many very fine roots in upper part decreasing to few very fine roots in the lower part, most roots are along the faces of prisms; few very fine pores; continuous distinct intersecting slickensides in the lower part; disseminated lime; strongly effervescent; strongly alkaline; gradual boundary. (10 to 20 inches thick)
BC--24 to 28 inches; olive gray (5Y 5/2) clay, olive gray (5Y 4/2) moist; weak medium prismatic structure; very hard, very firm, moderately sticky and very plastic; few fine roots; few weathered shale chips; disseminated lime; strongly effervescent; moderately alkaline (pH 8.4); gradual boundary. (0 to 13 inches thick)
Cr--28 to 60 inches; gray (5Y 5/1) semiconsolidated shale, dark gray (5Y 4/1) moist; few fine roots in upper part along bedding planes; slightly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Blaine County, Montana; 150 feet west and 30 feet south of the NE corner of sec. 14, T.26 N., R. 23 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 47 degrees F.
Moisture control section - between 4 to 12 inches.
Control section - 45 to 60 percent clay.
Depth to Cr horizon - 20 to 40 inches.
In most years, this soil has 1/4- to 2-inch cracks that extend from the surface to 20 or 30 inches from late June through September. Intersecting slickensides and pressure faces are faint to prominent. A dry phase is recognized.
A horizon - Hue: 5Y, 2.5Y, or 10YR
Value: 4 or 5 dry, 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay or silty clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 30 percent--0 to 15 percent greater than 3 inches, 0 to 15 percent pebbles
EC: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 8.4
A cobbly phase is recognized.
Bss horizon - Hue: 5Y, 2.5Y, or 10YR
Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4
Texture: clay or silty clay
Clay content: 45 to 60 percent
EC: 0 to 4 mmhos/cm
Reaction: pH 6.6 to 9.0
Some pedons have a Bkssy horizon.
BC horizon - Hue: 5Y, 2.5Y, or 10YR
Value: 4, 5, or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay or silty clay
Clay content: 45 to 60 percent
EC: 0 to 4 mmhos/cm
Reaction: pH 6.6 to 9.0
Some pedons have a By horizon with 1 to 3 percent gypsum and 0 to 20 percent soft shale fragments.
COMPETING SERIES:
Aaberg (CO) - moderately well drained; has a mesic temperature regime.
Styers (T)(CO) - hues of 7.5YR and redder in the control section.
GEOGRAPHIC SETTING:
Landform - sedimentary plains; escarpments; hills; ridges.
Elevation - 1,900 to 4,700 feet.
Slope - 0 to 45 percent.
Parent material - residuum or colluvium derived from semiconsolidated shale.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 13 to 19 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 90 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; very slow permeability.
USE AND VEGETATION: Barkof soils are used mainly for rangeland and dryland cropland. Potential native vegetation is mainly rough fescue, bluebunch wheatgrass, green needlegrass, and western wheatgrass.
DISTRIBUTION AND EXTENT: Barkof soils are of moderate extent in central and eastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Blaine County, Montana, 1976.
REMARKS: Soil interpretations record: MT0261, MT0855. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the surface to 7 inches (A horizon); a particle-size control section from 10 to 28 inches (Bss and BC horizons); and a paralithic contact at a depth of 28 inches. Barkof soils have a frigid temperature regime and an ustic moisture regime.