LOCATION HOOSAN MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive Calcic Pachic Haplocryolls
TYPICAL PEDON: Hoosan silty clay loam, pasture land. (Colors are for dry soil unless otherwise noted.)
A1--0 to 6 inches; very dark gray (10YR 3/1) silty clay loam, black (10YR 2/1) moist; moderate fine granular structure; hard, friable, slightly sticky and slightly plastic; neutral (pH 7.0); abrupt smooth boundary. (5 to 7 inches thick)
A2--6 to 12 inches; very dark gray (10YR 3/1) silty clay loam, black (10YR 2/1) moist; weak medium prismatic structure parting to weak medium and fine subangular blocky; hard, friable, slightly sticky and moderately plastic; many fine and very fine roots; many fine and very fine pores; slightly effervescent; neutral (pH 7.2); diffuse wavy boundary. (4 to 9 inches thick)
Bw1--12 to 20 inches; grayish brown (2.5Y 5/2) silty clay loam, very dark grayish brown (2.5Y 3/2) moist; moderate medium prismatic structure parting to moderate fine subangular blocky; very hard, friable, moderately sticky and moderately plastic; many fine and very fine roots; many fine and very fine pores; slightly effervescent; slightly alkaline (pH 7.4); clear wavy boundary. (7 to 10 inches thick)
Bw2--20 to 28 inches; grayish brown (2.5Y 5/2) heavy silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic structure parting to moderate fine subangular blocky; very hard, firm, moderately sticky and moderately plastic; many fine and very fine roots; many fine and very fine pores; strongly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (5 to 10 inches thick)
Bk--28 to 34 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate fine subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common fine and very fine roots; many fine and very fine pores; violently effervescent; many fine threads of lime; moderately alkaline (pH 8.0); clear wavy boundary. (5 to 9 inches thick)
BCk--34 to 60 inches; light brownish gray (2.5Y 6/2) silty clay loam with few limestone pebbles, grayish brown (2.5Y 5/2) moist; massive; hard, friable, slightly sticky and moderately plastic; very few fine and very fine roots; many fine and very fine pores; common fine threads of lime; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Fergus County, Montana; about 500 feet north and 450 feet west of the SE corner of sec. 14, T. 13 N., R. 18 E.
RANGE IN CHARACTERISTICS:
Soil temperature: 40 to 44 degrees F.
Mollic epipedon thickness: 16 to 24 inches
Rock fragments: limestone and calcareous sandstone
Depth to calcic horizon: 16 to 26 inches
A1 and A2 horizons:
Hue: 10YR
Value, dry: 3 or 4
Value, moist: 2
Chroma: 1 or 2
Texture: silty clay loam
Clay content: 30 to 40 percent
Rock fragments: 0 to 5 percent pebbles
Reaction: pH 6.6 to 7.8
Bw horizons:
Hue: 10YR or 2.5Y
Value, dry: 3, 4, or 5
Value, moist: 3 or 4
Chroma: 1 or 2
Texture: silty clay loam, clay loam, or silty clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 5 percent pebbles
Calcium carbonate equivalent: 5-15 percent
Reaction: pH 7.4 to 8.4
Bk horizons:
Hue: 2.5Y through 7.5YR
Value, dry: 4 or 5
Value, moist: 3 or 4
Chroma: 1 or 2
Texture: silty clay loam, clay, silty clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 5 percent pebbles
Calcium carbonate equivalent: 15-30 percent
Reaction: pH 7.4 to 8.4
BCk horizon:
Hue: 2.5Y through 7.5YR
Value, dry: 6 or 7
Value, moist: 4 or 5
Chroma: 1, 2 or 3
Texture: silty clay loam, clay loam, silty clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent pebbles
Calcium carbonate equivalent: 15-30 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Ryman (CO) - does not have horizons of secondary carbonate accumulation.
GEOGRAPHIC SETTING: Hoosan soils are on terraces, fans, and foot slopes in the mountain valleys. Slope gradients are 2 to 15 percent. Elevations are 4700 to 5600 feet. Hoosan soils formed in clayey alluvium weathered from hard calcareous clayey shales, limestone, or calcareous sandstone. The climate is cool with long cold winters and moist springs and summers. Mean annual temperature is 30 to 42 degrees F. Mean annual precipitation is 19 to 30 inches. The growing season is 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Adel, Kildor, Raynesford, Skaggs, and Waybe series. Kildor and Skaggs soils are moderately deep to shale or limestone. Adel and Raynesford soils have a fine-loamy control section. The Waybe soils are shallow to clayey shale.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Used for hay, pasture, cropland, and rangeland. Native vegetation consists of basin wildrye, western wheatgrass, Columbia needlegrass, bearded wheatgrass, big bluegrass, basin wildrye, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Intermountain valleys of central Montana. Hoosan soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Fergus County, Montana, 1979.
Remarks: Classification updated 10/06.
Diagnostic feature recognized in this pedon are:
Mollic epipedon - the zone from 0 to 12 inches (A1 and A2 horizons).
Cambic horixon - the zone from 12 to 28 inches (Bw1 and Bw2 horizons).
Calcic horizon - the zone from 28 to 60 inches (Bk and BCk).
Changed from Fine, mixed, superactive Pachic Haplocryolls to Fine, mixed, superactive Calcic Pachic Haplocryolls.