LOCATION CHUGTER MTEstablished Series
TAXONOMIC CLASS: fine-loamy, mixed, superactive, mesic Aridic Haplustolls
TYPICAL PEDON: Chugter loam - grassland. (Colors are for dry soil unless otherwise noted)
Ap--0 to 6 inches; reddish brown (5YR 5/3) loam, dark reddish brown (5YR 3/3) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine interstitial pores and few fine tubular pores; slightly alkaline; abrupt smooth boundary. (Combined A horizons 3 to 6 inches thick)
Bw1--6 to 10 inches; reddish brown (5YR 4/3) heavy loam, dark reddish brown (5YR 3/3) moist; moderate coarse prismatic structure; hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine and few fine tubular pores; thin bridging of clay between sand grains; slightly alkaline; clear wavy boundary. (4 to 8 inches thick)
Bw2--10 to 16 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/4) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine pores; few fine reddish brown shale and sandstone chips; slightly effervescent; gradual wavy boundary. (5 to 10 inches thick)
Bk1--16 to 29 inches; reddish brown (5YR 5/3)loam, reddish brown (5YR 4/4) moist; weak coarse blocky structure; hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine pores; few fine shale and sandstone chips; strongly effervescent; few very fine threads of lime; gradual wavy boundary. (10 to 20 inches thick)
Bk2--29 to 41 inches; light reddish brown (5YR 6/3) loam, reddish brown (5YR 4/4) moist; massive; hard, friable, nonsticky, slightly plastic; few very fine roots; common very fine pores; few fine shale chips; strongly effervescent; common threads of segregated lime; gradual wavy boundary. (10 to 20 inches thick)
C--41 to 63 inches; light reddish brown (5YR 6/3) loam, reddish brown (5YR 5/4) moist; massive; slightly hard, friable, nonsticky, slightly plastic; strongly calcareous.
TYPE LOCATION: Big Horn County, Montana; 525 feet west and 380 feet south of E 1/4 corner, section 10, T.9S., R.40E.
RANGE IN CHARACTERISTICS: The 10- to 40 -inch control section is loam or clay loam with 18 to 30 percent clay and 2 to 30 percent hard shale or sandstone gravel. There may be a lithic or paralithic contact below 40 inches. Chugter soils are usually dry but the surface horizons are occasionally wetted by summer rains of more than one inch intensity. Mean annual soil temperature is 48 degrees to 50 degrees F. The mollic epipedon is 7 to 16 inches thick. The soil has hue of 5YR or 2.5YR throughout.
The A horizon has value of 4 or 5, and chroma of 2 to 4.
The Bw horizon has color value of 5 or 4, and chroma of 3 to 5. It has weak to moderate medium and coarse prismatic structure and in some pedons has very thin clay bridging between sand grains.
The Bk horizon has value of 5 or 6 and 4 or 5 moist, and chroma of 3 to 6. Segregated lime occurs as few to common fine threads, films or masses and as coatings on the underside of shale and sandstone pebbles.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Chugter soils are on gently sloping to moderately steep fans, footslopes and terraces at elevations of 3,400 to 4,000 feet. They formed in loam and gravelly loam alluvium from calcareous sedimentary rock sources. At the type location the major source of the parent material is the red colored (burned) shale and sandstones of the Tongue River geologic formation associated with burned coal beds. The mean annual precipitation is 11 to 13 inches. Mean annual air temperature is 46 degrees to 48 degrees F. The frost-free period is 115 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Shirk, Wibaux and Travessilla soils on shale and sandstone uplands, and the Fort Collins, Heldt, McRae and Thurlow soils on the fans and foot slopes. Fort Collins, McRae and Thurlow soils have hue yellower than 7.5Y and Fort Collins and Thurlow soils have argillic horizons. Heldt soils have clayey textures. Wibaux have fragmental material and Travesilla soils have a lithic contact at depths of less than 20 inches.
DRAINAGE AND PERMEABILITY: Well-drained, slow runoff; moderate to moderately rapid permeability.
USE AND VEGETATION: Chugter soils are used mainly for nonirrigated hayland and for range. Some areas are used for dry cropland. Native vegetation is western wheatgrass, sideoats grama, needle-and-thread, prairie junegrass, big sagebrush and annual weeds.
DISTRIBUTION AND EXTENT: South-central Montana. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado.
SERIES ESTABLISHED: Big Horn County (Big Horn Area), Montana, 1970.
Remarks: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 10 inches (Ap and Bw1 horizons.