LOCATION KOYOKEE MTEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, frigid Mollic Haploxeralfs
TYPICAL PEDON: Koyokee gravelly loam, 4 to 15 percent slopes, in rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; strong medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine and medium roots and few coarse roots; 20 percent pebbles; neutral (pH 7.0); clear wavy boundary. (3 to 5 inches thick)
Bt--3 to 11 inches; light brownish gray (10YR 6/2) very gravelly silty clay, dark brown (10YR 4/3) moist; weak coarse subangular blocky structure; hard, firm, very sticky and very plastic; common very fine, fine and medium roots and few coarse roots; many prominent clay films on faces of peds; 35 percent pebbles and 10 percent cobbles; neutral (pH 7.2); gradual wavy boundary. (7 to 15 inches thick)
Btk--11 to 19 inches; pale brown (10YR 6/3) very cobbly clay loam, yellowish brown (10YR 5/4) moist; weak coarse subangular blocky structure; hard, firm, very sticky and very plastic; few very fine roots; common distinct clay films on faces of peds; 25 percent cobbles and 25 percent pebbles; disseminated lime; violently effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (0 to 10 inches)
Bk--19 to 60 inches; light yellowish brown (10YR 6/4) very cobbly sandy clay loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; 25 percent cobbles and 25 percent pebbles; disseminated lime; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Sanders County, Montana; 2,200 feet west and 2,500 feet south of the NE corner of sec. 31, T. 23 N., R. 23 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to lime - 10 to 20 inches.
The surface when mixed to a depth of 7 inches will not meet the requirements of a mollic epipedon.
A horizon - Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3
Clay content: 18 to 27 percent
Rock fragments: 15 to 35 percent - 0 to 10 percent cobbles; 15 to 25 percent pebbles
Reaction: pH 6.6 to 7.3
Bt horizon - Hue: 10YR or 7.5YR
Value: 5 or 6 dry; 4 moist
Chroma: 2, 3 or 4
Texture: silty clay or silty clay loam
Clay content: 35 to 50 percent
Rock fragments: 35 to 60 percent - 0 to 10 percent cobbles; 35 to 50 percent pebbles
Reaction: pH 6.6 to 7.8
Btk horizon - Hue: 10YR or 7.5YR
Value: 6 or 7 dry; 4, 5 or 6 moist
Chroma: 3 or 4
Texture: clay loam, silty clay
Clay content: 35 to 50 percent
Rock fragments: 35 to 60 percent - 10 to 25 percent cobbles; 25 to 35 percent pebbles
Calcium Carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
Bk horizon - Hue: 10YR or 7.5YR
Value: 6 or 7 dry; 4, 5 or 6 moist
Chroma: 3 or 4
Texture: silty clay loam, sandy clay loam
Clay content: 27 to 35 percent
Rock fragments: 35 to 60 percent - 10 to 25 percent cobbles; 25 to 35 percent pebbles
Calcium Carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - alluvial fans and stream terraces.
Elevation - 2,800 to 3,200 feet.
Slope- 4 to 30 percent.
Parent material - Tertiary sediments.
Climate - long, cold winters; moist springs and falls; hot, dry summers.
Mean annual precipitation - 14 to 17 inches.
Mean annual temperature - 41 to 45 degrees F.
Frost-free period - 105 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Koyokee soils are used for pasture and rangeland. The potential native plant community is mainly bluebunch wheatgrass, rough rescue, prairie junegrass, and big sage.
DISTRIBUTION AND EXTENT: Koyokee soils are of limited extent in the intermountain valleys of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sanders County, Montana, 1997.
REMARKS: Soil interpretation record: MT1224. Diagnostic horizons and other features recognized in this pedon are: a three inch dark colored surface (A horizon); an argillic horizon from 3 to 19 inches (Bt and Btk horizons); carbonate accumulations from 11 to 60 inches (Btk and Bk horizons); a particle size control section from 3 to 19 inches (Bt and Btk horizons). Koyokee soils have a frigid temperature regime and a xeric moisture regime.