LOCATION DUCKCREEK MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive Ustic Argicryolls
TYPICAL PEDON: Duckcreek loam, in rangeland (Colors are for dry soil unless otherwise noted).
A--0 to 6 inches; brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine and medium roots; many very fine and fine pores; 5 percent pebbles, 5 percent stones; neutral (pH 7.2); clear smooth boundary. (5 to 12 inches thick)
Bt1--6 to 15 inches; dark yellowish brown (10YR 4/4) clay loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure parting to strong fine granular; hard, friable, moderately sticky and moderately plastic; common very fine and few fine and medium roots; common very fine pores; common faint discontinuous clay films on faces of peds; 10 percent pebbles; neutral (pH 7.2); clear smooth boundary.
Bt2--15 to 29 inches; light yellowish brown (10YR 6/4) gravelly clay loam, brown (10YR 5/3) moist; weak medium subangular blocky structure parting to moderate fine granular; hard, friable, moderately sticky and moderately plastic; few very fine and fine roots; common very fine interstitial and tubular pores; common faint discontinuous clay films on faces of peds; 20 percent pebbles; slightly alkaline (pH 7.4); clear smooth boundary. (Combined thickness of the Bt1 and Bt2 horizon 15 to 25 inches)
Bk--29 to 36 inches; light gray (2.5Y 7/2) sandy clay loam, grayish brown (2.5Y 5/2) moist; weak coarse prismatic structure; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine interstitial and tubular pores; common fine soft masses of lime; 30 percent soft shale fragments; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 10 inches thick)
Cr--36 to 60 inches; semiconsolidated black shale; strongly effervescent.
TYPE LOCATION: Sweet Grass County, Montana; 200 feet east and 2400 feet south of the northwest corner of section 19, T.2 N., R.12 E.; Latitude 45 degrees, 54 minutes, 31 seconds N., Longitude 110 degrees, 17 minutes, 28 seconds W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 36 to 40 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 8 to 15 inches.
Depth to Bk horizon - 15 to 35 inches.
Depth to Cr horizon - 20 to 40 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 1, 2, or 3
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 25 percent-- 0 to 5 percent flagstones or stones, 0 to 5 percent cobbles, 0 to 15 percent channers or pebbles; 0 to 20 percent soft shale chips.
Reaction: pH 5.6 to 7.3
Bt1 horizon - Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2, 3 or 4
Texture: clay loam or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 25 percent-- 0 to 5 percent cobbles, 0 to 20 percent channers or pebbles; 0 to 20 percent soft shale chips.
Reaction: pH 5.6 to 7.3
Bt2 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3 or 4
Texture: clay loam or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 35 percent-- 0 to 5 percent cobbles, 0 to 30 percent channers or pebbles; 0 to 20 percent soft shale chips.
Reaction: pH 6.1 to 7.8
Bk horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: loam, clay loam or clay
Clay content: 27 to 45 percent
Rock fragments: 0 to 35 percent--0 to 5 percent cobbles, 0 to 30 percent channers or pebbles; 10 to 35 percent soft shale chips.
Calcium Carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Bangtail (MT) - does not have horizons of secondary calcium carbonate accumulation.
Bridger (MT) - does not have a paralithic contact above 60 inches.
Echard (UT) - does not have a paralithic contact above 60 inches; formed in soft rhyolitic tuff or strongly cemented ash.
Mollet (MT) - does not have a paralithic contact above 60 inches; does not have horizons of secondary calcium carbonate accumulation.
Rattler (MT) - does not have a paralithic contact above 60 inches.
Sevier (UT) - has Bt horizon which is 4 to 10 inches thick; is moderately well drained; does not have horizons of secondary calcium carbonate accumulation.
GEOGRAPHIC SETTING:
Landform - hills, mountains, escarpments.
Elevation - 5,600 to 8,300 feet.
Slope - 4 to 60 percent.
Parent material - residuum derived from cretaceous interbedded shale and sandstone.
Climate - long, cold winters; cool, moist springs; short summers.
Mean annual precipitation - 19 to 25 inches.
Mean annual air temperature - 35 to 43 degrees F.
Frost-free period - 50 to 70 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Duckcreek soils are used mainly for rangeland and wildlife habitat. Potential native vegetation may include Idaho fescue, Richardson needlegrass, Columbia needlegrass, mountain brome, lupine, and sticky geranium.
DISTRIBUTION AND EXTENT: Duckcreek soils are of small extent in south central Montana.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sweet Grass County, Montana, 1999.
REMARKS: Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 15 inches (A and Bt1 horizons); an argillic horizon from 6 to 29 inches (Bt1 and Bt2 horizons); a horizon of secondary calcium carbonate accumulation from 29 to 36 inches (Bk horizon); a paralithic contact of interbedded soft shale and sandstone from 36 to 60 inches (Cr horizon). Duckcreek soils have a cryic temperature regime and an ustic moisture regime.