LOCATION CASTLE MTEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, frigid Leptic Udic Haplusterts
TYPICAL PEDON: Castle loam, in rangeland (Colors are for dry soil unless otherwise noted).
A--O to 3 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate fine and very fine granular structure; hard, firm, moderately sticky and very plastic; many fine and very fine,common medium, and few coarse roots; slightly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 9 inches thick)
Bw1--3 to 8 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate fine subangular blocky structure; extremely hard, firm, moderately sticky and very plastic; many fine and very, common medium and few coarse roots; many fine and very fine pores; slightly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (0 to 8 inches thick)
Bw2--8 to 14 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; strong very fine angular blocky structure; common slickensides; extremely hard, firm, moderately sticky and very plastic; common fine and very fine, few medium and coarse roots; many fine and very fine and few medium pores; strongly effervescent; moderately alkaline (pH 8.2); clear irregular boundary. (5 to 14 inches thick)
Bw3--14 to 18 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; common fine yellowish brown (10YR 5/6) mottles; moderate fine and very fine angular blocky structure; few slickensides; extremely hard, firm, moderately sticky and very plastic; common fine and very fine, few medium and coarse roots; many fine and very fine and few medium pores; few fine irregular soft masses of lime; strongly effervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (4 to 10 inches thick)
Bk--18 to 32 inches; gray (5Y 6/1) clay, light gray (5Y 5/1) moist; common fine yellowish brown (10YR 5/6) mottles; weak fine and very fine subangular blocky structure; few slickensides; extremely hard, firm, moderately sticky and very plastic; common very fine and few fine roots; many very fine and common fine pores; common fine irregular soft masses of lime; strongly effervescent; moderately alkaline (pH 8.0); diffuse wavy boundary. (10 to 18 inches thick)
Cr--32 to 60 inches; gray (5Y 5/1) clay shale, dark gray (5Y 4/1) moist; common fine light olive brown (2.5Y 5/4) mottles; slightly effervescent; neutral (pH 6.8).
TYPE LOCATION: Fergus County, Montana; 2420 feet north and 220 feet east of the southwest corner of sec. 34, T. 14N., R. 19E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 40 to 47 degrees F.
Mollic epipedon thickness - 10 to 15 inches.
Depth to the paralithic contact - 20 to 40 inches
A horizon - Hue: 10YR or 2.5Y
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 1 or 2
Clay content: 45 to 65 percent
Reaction: pH 7.4 to 8.4
Bw horizons - Hue: 10YR or 2.5Y
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 1 or 2
Clay content: 60 to 70 percent
Reaction: pH 7.4 to 8.4
Bk horizon - Hue: 2.5Y, 5Y or neutral
Value: 5 or 6 dry, 4 or 5 moist
Clay content: 60 to 70 percent
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 6.6 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - hills and sedimentary plains
Elevation - 4,500 to 5,600 feet
Slope - 2 to 35 percent
Parent material - residuum from clay shale
Climate - cool, subhumid
Mean annual precipitation - 19 to 26 inches
Mean annual temperature - 38 to 42 degrees F.
Frost-free period - 70 to 90 days.
DRAINAGE AND PERMEABILITY: Well drained; very slow permeability.
USE AND VEGETATION: These soils are used mainly for rangeland and to a lesser extent for pasture or dryland crops. The principal native vegetation is rough fescue, Columbia needlegrass, Richardson needlegrass, mountain brome, forbs and shrubs.
DISTRIBUTION AND EXTENT: central Montana. This series is not extentsive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Reconnaissance soil survey of Central Montana, 1946.
REMARKS: Diagnostic horizons and features recognized in this pedon are: a cambic horizon from 3 to 18 inches (Bw horizons); accumulation of secondary carbonates from 18 to 32 inches (Bk horizon); a particle-size control section from 10 to 32 inches (part of the Bw2, the Bw3, and the Bk horizons); and a paralithic contact at 32 inches (Cr horizon). Castle soils have an ustic moisture regime and a frigid temperature regime.