LOCATION CLARKSTONE MTEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Torriorthentic Haplustolls
TYPICAL PEDON: Clarkstone silt loam, cultivated (colors are for dry soil unless otherwise noted).
Ap--0 to 7 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; common very fine, fine, and few medium roots; slightly alkaline (pH 7.6); clear smooth boundary. (4 to 7 inches thick)
Bw--7 to 9 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine, fine, and medium roots; slightly alkaline (pH 7.8); clear smooth boundary. (2 to 5 inches thick)
Bk1--9 to 22 inches; light gray (10YR 7/2) silt loam, brown (10YR 4/3) moist; weak coarse subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine roots; disseminated lime; violently effervescent; strongly alkaline (pH 8.5); clear smooth boundary. (6 to 13 inches thick)
Bk2--22 to 27 inches; light gray (10YR 7/2) silt loam, brown (10YR 4/3) moist; massive; soft, very friable, slightly sticky and nonplastic; few very fine roots; few fine soft masses of lime; disseminated lime; violently effervescent; strongly alkaline (pH 8.7); clear smooth boundary. (0 to 20 inches thick)
BC--27 to 60 inches; light gray (10YR 7/2) silt loam, brown (10YR 4/3) moist; massive; soft, very friable, slightly sticky and nonplastic; disseminated lime; violently effervescent; strongly alkaline (pH 8.7).
TYPE LOCATION: Gallatin County, Montana; 2,300 feet south and 1,500 feet east of the NW corner of Sec. 33, T. 4 N., R. 3 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 45 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in all parts between four tenths and five tenths of the cumulative days per year when the soil temperature at 20 inches is higher than 41 degrees F.
Mollic epipedon thickness - 7 to 9 inches.
Depth to calcic horizon - 7 to 9 inches.
Ap horizon - Value: 2 or 3 moist
Chroma: 2 or 3
Clay content: 10 to 20 percent
Reaction: 6.6 to 7.8
Bw horizon - Value: 5 or 6 dry, 3, 4 or 5 moist
Chroma: 2 or 3
Clay content: 10 to 20 percent
Reaction: 7.4 to 8.4
Bk horizons - Value: 6 or 7 dry, 4, 5 or 6 moist
Chroma: 2 or 3
Clay content: 10 to 18 percent; clay size carbonates--2 to 10 percent
Calcium carbonate equivalent: 15 to 30 percent
Reaction: 7.9 to 8.4
BC horizon - Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Clay content: 10 to 18 percent; clay size carbonates--2 to 10 percent
Calcium carbonate equivalent: 15 to 30 percent
Reaction: 7.9 to 8.4
Some pedons have 0 to 5 percent pebbles
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - alluvial fans, stream terraces.
Elevation - 3,900 to 5,000 feet.
Slope - 0 to 15 percent.
Parent material - very deep loess deposits.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches, much of which falls as snow and spring rains.
Mean annual temperature - 43 to 45 degrees F.
Frost-free period - 95 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Clarkstone soils are used for nonirrigated small grain.
DISTRIBUTION AND EXTENT: Clarkstone soils are of small extent in the intermountain valleys in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Gallatin County Area, Montana, 1997.
REMARKS: Soil interpretation record: MT1304. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 7 inches (Ap horizon); a calcic horizon from 9 to 27 inches (Bk1 and Bk2 horizons); a particle-size control section from 10 to 40 inches (Bk1, Bk2, and BC horizons). Clarkstone soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.