LOCATION EKAH MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Argiustolls
TYPICAL PEDON: Ekah clay loam, grassland (colors are for dry soil unless otherwise noted).
A1--0 to 2 inches; dark grayish brown (10YR 4/2) clay loam, very dark gray (10YR 3/1) moist; weak fine platy and weak fine granular structure; soft, very friable, slightly sticky and moderately plastic; many medium and fine roots; many fine and medium continuous vesicular and tubular pores; slightly acid (pH 6.2); clear smooth boundary. (2 to 6 inches thick)
A2--2 to 5 inches; dark grayish brown (10YR 4/2) clay loam, very dark gray (10YR 3/1) moist; moderate fine and medium platy structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine and fine roots; common fine and medium continuous vesicular pores; slightly acid (pH 6.2); clear smooth boundary. (2 to 4 inches thick)
AB--5 to 8 inches; grayish brown (10YR 5/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky parting to moderate fine and medium granular structure; hard, friable, slightly sticky and moderately plastic; common very fine and fine roots; common fine continuous vesicular and tubular pores; slightly acid (pH 6.2); abrupt smooth boundary. (0 to 4 inches thick)
Bt1--8 to 13 inches; grayish brown (10YR 5/2) silty clay, dark brown (10YR 4/3) moist; strong medium prismatic parting to strong medium angular blocky structure; extremely hard, extremely firm, moderately sticky and moderately plastic; common very fine and fine roots; common fine continuous vesicular and tubular pores; continuous faint clay films on faces of peds; organic staining on faces of peds; neutral (pH 7.2); clear smooth boundary.
Bt2--13 to 17 inches; grayish brown (10YR 5/3) silty clay, dark brown (10YR 4/3) moist; strong medium subangular blocky structure parting to moderate fine subangular blocky; very hard, very firm, moderately sticky and moderately plastic; few very fine and fine roots; few fine continuous vesicular pores; many faint clay films on faces of peds; slightly alkaline (pH 7.6); clear smooth boundary. (Combined thickness of Bt horizons is 8 to 18 inches.)
Btk--17 to 25 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and moderately plastic; few fine and very fine roots; few very fine continuous vesicular pores; common faint clay films on faces of peds; common medium masses of lime; strongly effervescent; slightly alkaline (pH 7.6); gradual wavy boundary. (0 to 8 inches thick)
Bk1--25 to 38 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky and moderately plastic; few very fine roots; few very fine continuous vesicular pores; disseminated lime; few fine masses of lime; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (8 to 15 inches thick)
Bk2--38 to 60 inches; light gray (10YR 7/2) clay loam, pale brown (10YR 6/3) moist; massive; slightly hard, friable, slightly sticky and moderately plastic; few very fine roots; few very fine continuous vesicular pores; disseminated lime; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Powell County, Montana; about 500 feet east and 500 feet north of the SW corner of sec. 21, T. 12 N., R. 12 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 46 degrees F.
Moisture control section - 4 to 12 inches.
Mollic epipedon thickness - 7 to 16 inches.
Depth to Bk horizon - 12 to 40 inches.
Depth to Bt horizon - 6 to 14 inches.
A1, A2 horizons - Chroma: 1 or 2
Texture: loam, clay loam, silty clay loam
Clay content: 20 to 30 percent
Rock fragments: 0 to 25 percent--0 to 15 percent pebbles; 0 to 10 percent cobbles
Reaction: pH 6.1 to 7.3
AB horizon - Chroma: 2 or 3
Texture: silty clay loam, clay loam
Clay content: 27 to 40 percent
Reaction: pH 6.1 to 7.3
Bt horizons - Value: 4, 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: silty clay or clay
Clay content: 45 to 60 percent
Rock fragments: 0 to 10 percent pebbles
Reaction: pH 6.6 to 7.8
Btk horizon - Chroma: 3 or 4
Texture: clay loam, silty clay loam
Clay content: 30 to 40 percent
Rock fragments: 0 to 10 percent pebbles
Reaction: pH 7.4 to 7.8 percent
Bk1 horizon - Value: 6, 7 or 8 dry; 4, 5 or 6 moist
Chroma: 3 or 4
Texture: clay loam, silty clay loam
Clay content: 30 to 35 percent
Rock fragments: 0 to 10 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
Bk2 horizon - Value: 6, 7 or 8 dry; 4, 5 or 6 moist
Chroma: 2, 3, or 4
Texture: clay loam, loam
Clay content: 25 to 35 percent
Rock fragments: 0 to 35 percent pebbles
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Absarokee (MT) - lithic contact at 20 to 40 inches; does not have a calcic horizon.
Acree (CO) - does not have a calcic horizon.
Barela (NM) - has a lithic contact at 40 to 60 inches.
Capillo (NM) - does not have a Bk horizon.
Delson (CO) - does not have a Bk horizon.
Herm (CO) - does not have a Bk horizon.
Morapos (CO) - does not have a calcic horizon.
Moreno (NM) - does not have a Bk horizon.
Nortez (CO) - has a lithic contact at 20 to 40 inches, does not have a Bk horizon.
Pramiss (CO) - has a paralithic contact at 20 to 40 inches.
Ricot (CO) - has a lithologic discontinuity at 15 to 30 inches; does not have a calcic horizon.
Tamaneen (MT) - has a lithologic discontinuity at 17 to 40 inches.
Tukuhnik (UT) - has a lithic contact at 40 to 60 inches.
Work (MT) - does not have a calcic horizon.
Zau (CO) - has a paralithic contact at 20 to 40 inches; does not have a Bk horizon.
GEOGRAPHIC SETTING:
Landform - alluvial fans, stream terraces.
Elevation - 3,800 to 6,200 feet.
Slope - 0 to 15 percent.
Parent material - clayey alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 39 to 44 degrees F.
Frost-free period - 70 to 90 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Ekah soils are used mainly for dryland and irrigated crops and range. Potential native vegetation is mainly western wheatgrass, thickspike wheatgrass, needle and thread, Idaho fescue, blue gramma, Sandberg bluegrass, grasses, and forbs.
DISTRIBUTION AND EXTENT: Ekah soils are of moderate extent in the foothills and mountain valleys of western Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Granite County (Philipsburg-Drummond Area), Montana in 1972. Type location moved to Powell County, Montana, 1993.
REMARKS: Soil Interpretations Record: MT0052. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 8 inches (A1, A2 and AB horizons); argillic horizons from 8 to 25 inches (Bt1, Bt2 and Btk horizons); horizons of calcium carbonate accumulation from 25 to 60 inches (Btk, Bk1 and Bk2 horizons); a particle size control section from 8 to 25 inches (Bt1, Bt2 and Btk horizons). Ekah soils have a frigid temperature regime and an ustic moisture regime.