LOCATION KOBARTER MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Aridic Haplustepts
TYPICAL PEDON: Kobarter clay loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; brown (10YR 5/3) clay loam, dark grayish brown (10YR 4/2) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and very fine roots; many fine and very fine pores; 10 percent pebbles; moderately alkaline (pH 8.0); clear smooth boundary. (3 to 7 inches thick)
Bw--5 to 18 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm, moderately sticky and moderately plastic; common fine and very fine roots; many fine and very fine pores; 5 percent pebbles; disseminated lime; violently effervescent; moderately alkaline (pH 8.4); gradual smooth boundary. (7 to 15 inches thick)
Bkz--18 to 48 inches; very pale brown (10YR 7/4) silty clay, light yellowish brown (2.5Y 6/4) moist; weak medium prismatic structure parting to moderate medium subangular blocky; very hard, firm, moderately sticky and moderately plastic; few fine and very fine roots; common fine and very fine pores; disseminated lime, common fine threads of lime; 5 percent pebbles; few fine threads of soluble salts; strongly effervescent; moderately alkaline (pH 8.2); gradual smooth boundary. (20 to 50 inches thick)
Bz--48 to 60 inches; pale brown (10YR 6/3) silty clay, brown (10YR 5/3) moist; massive; very hard, firm, moderately sticky and moderately plastic; few very fine roots; few very fine pores; 5 percent pebbles; few fine threads of soluble salts; slightly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Jefferson County, Montana; 500 feet west and 600 feet south of the NE corner of sec. 10, T. 3 N., R. 1 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 46 degrees F.
Moisture control section - between 4 and 12 inches, dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature is 41 degrees F and higher.
Depth to Bkz horizon - 10 to 22 inches.
The surface layer, when mixed to 7 inches, does not meet the requirements for a mollic surface epipedon.
A horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3
Clay content: 27 to 40 percent
Rock fragments: 0 to 35 percent--0 to 10 percent cobbles, 0 to 25 percent pebbles
Reaction: pH 7.4 to 8.4
Bw horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam, silty clay, or clay
Clay content: 30 to 45 percent
Rock fragments: 0 to 5 percent pebbles
Calcium carbonate equivalent: 2 to 10 percent
Reaction: pH 7.4 to 8.4
Bkz horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: clay loam, silty clay loam, silty clay, or clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 5 percent pebbles
Calcium carbonate equivalent: 3 to 15 percent
Electrical conductivity: 2 to 8 mmhos/cm
Reaction: pH 7.4 to 9.0
Bz horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam, silty clay loam, silty clay, or clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 5 percent
Electrical conductivity: 4 to 16 mmhos/cm
Calcium carbonate equivalent: 2 to 10 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES:
Alzada (MT) - has a lithologic discontinuity; has horizon of gypsum accumulation.
Zaytony (MT) - has SAR of 16 to 30 and EC of 16 to 32 mmhos/cm in the Bknz horizon.
GEOGRAPHIC SETTING:
Landform - alluvial fans, stream terraces, drainageways, knolls and hills.
Elevation - 3,800 to 5,000 feet.
Slope- 2 to 35 percent.
Parent material - alluvium derived primarily from semiconsolidated shale and siltstone.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 44 degrees F.
Frost-free period - 90 to 115 days.
DRAINAGE AND PERMEABILITY: Well drained, slow permeability.
USE AND VEGETATION: Kobarter soils are primarily used for irrigated and nonirrigated cropland and for rangeland. The potential native vegetation is mainly green needlegrass, bluebunch wheatgrass, western wheatgrass, blue grama, prairie junegrass, broom snakeweed, big sagebrush, and rubber rabbitbrush.
DISTRIBUTION AND EXTENT: Kobarter soils are of small extent in the intermountain valleys of southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretations records: MT1568. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches, mixed (A, Bw horizons); a cambic horizon from 5 to 18 inches (Bw horizon); a particle-size control section from 10 to 40 inches (Bw, Bkz horizons); horizons of secondary calcium carbonate accumulation from 18 to 48 inches (Bkz horizon); horizons of soluble salt accumulation from 18 to 60 inches (Bkz, Bz horizons). Kobarter soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.