LOCATION KOKORUDA MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Kokoruda loam, in forest (colors are for dry soil unless otherwise noted).
Oi--1 inch to 0; leaves, twigs, roots, and partially decomposed leaves and twigs
A1--0 to 5 inches; dark gray (10YR 4/1) loam, very dark gray (10YR 3/1) moist; weak medium and fine subangular blocky structure; soft, very friable, moderately sticky and slightly plastic; many very fine and few fine, medium and coarse roots; many very fine and few fine pores; 10 percent pebbles; slightly acid (pH 6.2); clear wavy boundary.
A2--5 to 11 inches; dark gray (10YR 4/1) cobbly loam, very dark gray (10YR 3/1) moist; weak medium and fine subangular blocky structure; soft, very friable, moderately sticky and slightly plastic; many very fine and few fine, medium, and coarse pores; 15 percent cobbles, 15 percent pebbles; slightly acid (pH 6.1); clear smooth boundary. (Combined thickness of A horizons is 7 to 15 inches)
Bt1--11 to 15 inches; pale brown (10YR 6/3) cobbly clay loam, brown (10YR 5/3) moist; weak medium prismatic structure parting to moderate medium and fine subangular blocky; slightly hard, friable, moderately sticky and slightly plastic; many very fine and few fine, medium, and coarse roots; many very fine and few fine tubular and interstitial pores; many faint clay films on faces of peds and bridging sand grains; 15 percent cobbles, 10 percent pebbles; neutral (pH 6.6); clear wavy boundary.
Bt2--15 to 33 inches; light yellowish brown (10YR 6/4) cobbly clay loam, brown (10YR 5/3) moist; moderate medium prismatic structure parting to moderate medium and fine subangular blocky; slightly hard, friable, moderately sticky and slightly plastic; many very fine and few fine and medium roots; many very fine and few fine tubular and interstitial pores; many faint clay films on faces of peds and bridging sand grains; 15 percent cobbles, 15 percent pebbles; slightly acid (pH 6.1); clear wavy boundary. (Combined thickness of Bt horizons is 15 to 35 inches)
BC--33 to 60 inches; pale brown (10YR 6/3) very cobbly clay loam, light olive brown (2.5Y 5/4) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few very fine and fine roots; common very fine and few fine tubular and interstitial pores; 20 percent cobbles, 25 percent pebbles; slightly acid (pH 6.1).
TYPE LOCATION: Jefferson County, Montana; 2,600 feet south and 150 feet east of the NW corner of sec. 30, T. 9 N., R. 2 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 38 to 44 degrees F.
Moisture control section - between 4 and 12 inches.
Thickness of mollic epipedon - 7 to 15 inches.
A horizons - Hue: 10YR or 2.5Y
Value: 3 or 4 dry; 2 or 3 moist
Clay content: 10 to 27 percent
Rock fragments: 10 to 35 percent--0 to 15 percent cobbles, 10 to 20 percent pebbles
Reaction: pH 6.1 to 7.3
Bt horizons - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4
Texture: sandy clay loam, loam, or clay loam
Clay content: 18 to 35 percent
Rock fragments: 10 to 35 percent--0 to 15 percent cobbles and 10 to 20 percent pebbles
Reaction: pH 6.1 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3, 4, or 6
Texture: sandy loam, sandy clay loam, loam, or clay loam
Clay content: 15 to 30 percent
Rock fragments: 20 to 50 percent--0 to 20 percent cobbles, 20 to 30 percent pebbles
Reaction: pH 5.6 to 7.3
COMPETING SERIES:
Bottineau (ND) - has horizon of secondary carbonate accumulation, formed in till.
Doughty (MT) - has calcic horizon; has discontinuity with more than 50 percent coarse fragments.
Farside (MT) - does not have an O horizon.
Forman (ND) - has horizons of secondary carbonate accumulation; formed in till.
Sipple (MT) - has calcic horizon; has discontinuity with more than 50 percent coarse fragments.
Watne (MT) - has calcic horizon.
GEOGRAPHIC SETTING:
Landform - alluvial fans, drainageways, swales and sideslopes of hills.
Elevation - 4,400 to 6,000 feet.
Slope- 8 to 35 percent.
Parent material - alluvium derived from mixed rock sources.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 24 inches.
Mean annual air temperture - 36 to 42 degrees F.
Frost-free period - 70 to 105 days.
DRAINAGE AND PERMEABILITY: Well drained, moderately slow permeability.
USE AND VEGETATION: Kokoruda soils are primarily used for woodland and wildlife habitat. The potential native vegetation is mainly quaking aspen, common snowberry, white spiraea, western yarrow, woodland strawberry, northern bedstraw, heartleaf arnica, woods rose, Kentucky bluegrass, pinegrass, Oregongrape, timothy, clover, moderately sticky geranium, danthonia, and mountain brome.
DISTRIBUTION AND EXTENT: Kokoruda soils are of small extent in southwestern Montana.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT1503. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the mineral surface to 11 inches (A1 and A2 horizons); an argillic horizon from 11 to 33 inches (Bt1 and Bt2 horizons); a particle-size control section from 11 to 33 inches (Bt1 and Bt2 horizons). Kokoruda soils have a frigid temperature regime and an ustic moisture regime.