LOCATION ROTHICAN WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Calciustolls
TYPICAL PEDON: Rothican loam on a 4 percent west-facing fan apron; utilized as rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 8 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine roots; slightly effervescent, lime disseminated; mildly alkaline; clear smooth boundary. (7 to 12 inches thick)
Bw--8 to 16 inches; light brown (7.5YR 6/4) gravelly loam, brown (7.5Y 4/4) moist; weak coarse prismatic structure parting to moderate fine subangular blocky; slightly hard, very friable, nonsticky and nonplastic; few fine roots; few thin clay films on faces of peds; 20 percent pebbles; strongly effervescent, lime as few fine soft masses; moderately alkaline; clear smooth boundary. (6 to 10 inches thick)
Bk--16 to 40 inches; light brown (7.5YR 6/4) gravelly loam, brown (7.5Y 5/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; 30 percent pebbles coated with calcium carbonate; strongly effervescent; moderately alkaline. (20 to 40 inches thick)
C--40 to 60 inches; light brown (7.5YR 6/4) very gravelly loam, brown (7.5YR 5/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; 40 percent pebbles; strongly effervescent, lime disseminated; moderately alkaline.
TYPE LOCATION: Weston County, Wyoming; 6 miles northeast of Newcastle; in the SE1/4, SE1/4 of sec. 19, T. 45 N., R. 60 W.
RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon is 7 to 12 inches. Depth to pedogenetic concentrations of secondary calcium carbonates and the calcic horizon range from 10 to 22 inches. Coarse fragments throughout the particle size control section range from 15 to 35 percent pebbles. Clay percent ranges from 18 to 27 percent. At depths of 40 inches or greater coarse fragments range from 30 to 60 percent pebbles. The mean annual soil temperature is 44 degrees F., and the mean summer soil temperature is 62 degrees F. The soil is dry in some part of the moisture control section more than .6 of the time that the soil temperature at a depth of 20 inches is 41 degrees F. or more.
The A horizon has hue of 7.5YR or 10YR, value of 4 or 5 dry and 3 moist, and chroma of 2 or 3. It is typically loam and less typically a gravelly loam with less than 30 percent pebbles. Reaction is mildly or moderately alkaline. EC ranges from 0 to 2 mmhos.
The Bw horizon, cambic horizon, has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 3 or 4. It is a gravelly loam. Reaction is mildly or moderately alkaline. EC is 0 to 2 mmhos.
The Bk horizon, calcic horizon, has hue of 10YR or 7.5YR, value of 6 through 8 dry, 5 through 7 moist, and chroma of 3 or 4. Texture is gravelly loam with carbonates coating the coarse fragments. Reaction is moderately or strongly alkaline. EC is 0 to 2 mmhos.
The C horizon has hue of 10YR or 7.5YR, value of 5 through 7 dry, 5 or 6 moist, and chroma of 3 or 4. Texture is typically gravelly loam above 40 inches but may be very gravelly loam below 40 inches. Reaction is moderately or strongly alkaline. EC is 0 to 2 mmhos.
COMPETING SERIES: These are the Emmons, Rothiemay, and Zinzer series. Emmons soils have hue of 5YR and silty clay loam control sections. Rothiemay soils have 15 to 60 percent clay size carbonates within the clay fraction and occur in 10- to 14-inch precipitation zones. The Zinzer soils have control sections with 35 to 60 percent fine sand or coarser, 0 to 15 percent coarse fragments, and sandy clay loam textures. They also occur in 7-inch precipitation zones.
GEOGRAPHIC SETTING: The Rothican soils occur on dissected relict fan aprons, fan piedmonts, and terraces. They formed in alluvial outwash of mixed origin. Slopes range from 2 to 40 percent. The annual temperatures ranges from about 40 to 45 degrees F. Annual precipitation ranges from 15 to 19 inches of which over half falls in March, April, May, and June. Estimated frost-free season is 90 to 110 days but will vary depending upon aspect and air drainage.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Colhill, Sugakool, and Vassett soils. The Colhill soils have skeletal control sections and lack a pedogenetic lime accumulation above 40 inches. The Sugakool soils have developed argillic horizons. The Vassett soils also have developed argillic horizons and fine-silty control sections.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; moderate permeability.
USE AND VEGETATION: Rothican soils are used for grazing and
wildlife habitat. Native vegetation is blue grama, needleandthread, western wheatgrass, and green needlegrass.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
DISTRIBUTION AND EXTENT: Black Hills footslopes in northeastern Wyoming. These soils are of small extent.
SERIES ESTABLISHED: Weston County, Wyoming; 1983.
REMARKS: Rothican is a coined name. This soil was coined as a variant until the final field review.