LOCATION SIMANNI COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Ustic Haplargids
TYPICAL PEDON: Simanni coarse sandy loam-rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 2 inches; pale brown (10YR 6/3) coarse sandy loam, brown (10YR 4/3) moist; weak fine granular structure; soft, very friable, slightly sticky and nonplastic; 5 percent gravel; slightly alkaline (pH 7.6); abrupt smooth boundary. (2 to 5 inches thick)
A2--2 to 6 inches; light yellowish brown (10YR 6/4) coarse sandy loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; 5 percent gravel; slightly alkaline (pH 7.8); clear smooth boundary. (0 to 4 inches thick)
AB--6 to 10 inches; light yellowish brown (10YR 6/4) coarse sandy loam; yellowish brown (10YR 5/4) moist; moderate coarse subangular blocky structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and nonplastic; 5 percent gravel; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 4 inches thick)
Bt--10 to 22 inches; light yellowish brown (10YR 6/4) sandy clay loam; yellowish brown (10YR 5/4) moist; moderate coarse subangular blocky structure parting to weak fine subangular blocky; hard, friable, moderately sticky and slightly plastic; common distinct clay films on ped faces; 5 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (10 to 15 inches thick)
Bk1--22 to 33 inches; reddish yellow (7.5YR 6/6) coarse sandy loam, strong brown (7.5YR 5/6) moist; weak coarse subangular blocky structure; slightly hard, friable; slightly sticky and nonplastic; 5 percent gravel; violently effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (10 to 25 inches thick)
Bk2--33 to 60 inches; reddish yellow (7.5YR 6/6) loamy coarse sand, strong brown (7.5YR 5/6) moist; massive; slightly hard, friable, slightly sticky and nonplastic; 5 percent gravel; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Moffat County, Colorado; about 7 miles northeast of Powderwash; about 2,600 feet east and 1,300 feet south of the northwest corner of Sec. 28, T. 12 N., R. 96 W.; Reservoir Draw USGS quadrangle; 40 degrees 58 minutes, 30 seconds north latitude, 108 degrees, 10 minutes, 55 seconds west longitude.
RANGE IN CHARACTERISTICS:
Soil moisture: aridic regime bordering on ustic.
Mean annual soil temperature ranges from 44 to 46 degrees F.
Mean summer soil temperature ranges from 61 to 64 degrees F.
Depth to secondary calcium carbonate ranges from 15 to 25 inches.
Depth to horizons which effervesce ranges from 5 to 20 inches.
Depth to the base of the argillic horizon ranges from 15 to 25 inches.
Particle-size control section (weighted averages)
Clay content: 18 to 27 percent
Content of fine and coarser sand: more than 35 percent
A horizons
Hue: 10YR or 7.5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4
Bt horizon
Hue: 10YR or 7.5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 through 6
Texture: sandy clay loam or coarse sandy loam
Reaction: slightly alkaline or moderately alkaline
Content of rock fragments: 0 to 10 percent
Bk horizons
Hue: 2.5Y through 7.5YR
Value: 6 or 7 dry, 5 or 6 moist
Chroma: 3 through 6
Texture: coarse sandy loam, loamy coarse sand or coarse sand
Content of rock fragments: 0 to 10 percent
COMPETING SERIES: These are the
Alcova,
Almy,
Bateson,
Bluerim,
Forelle,
Maysprings,
Satanka, and
Taffom series.
Alcova and Bateson soils have greater than 10 percent rock framents in the lower part.
Almy soils have hue redder than 7.5YR in the Bt horizon.
Bluerim soils have a paralithic contact.
Forelle soils have less than 35 percent fine and coarser sand in the argillic horizon.
Maysprings soils have C horizons with sandy textures.
Satanka soils have a paralithic contact.
Taffom soils have accumulations of secondary carbonates at depths of 40 inches or more.
GEOGRAPHIC SETTING: Simanni soils are on toe slopes. These soils formed in alluvium derived from sandstone. Slopes range from 1 to 10 percent. Elevation ranges from 6,000 to 6,500 feet. The mean annual precipitation ranges from 9 to 11 inches, the mean annual temperature ranges from 42 to 45 degrees F., and the frost-free season is 75 to 95 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hiatha, Kandaly, Ruedloff, Talamantes, and Tresano soils. The Hiatha soil is shallow. The Kandaly soil is in a sandy family. The Ruedloff soil is in a coarse-loamy family. The Tresano soil has less than 35 percent fine and coarser sand.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. Native vegetation consists of Indian ricegrass, needleandthread, streambank wheatgrass, western wheatgrass, shadscale, Nuttal saltbush, and Wyoming big sagebrush.
DISTRIBUTION AND EXTENT: These soils are in northwestern Colorado, MLRA 34A. The series is of moderate extent. Total acreage is about 12,500 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Moffat County (Moffat County Area), Colorado, 1991.
REMARKS: The diagnostic horizons recognized in this pedon are:
Ochric epipedon - the zone from 0 to 10 inches (A1, A2, and AB horizons)
Argillic horizon - the zone from 10 to 22 inches (Bt horizon)
Particle-size control section - The zone from 10 to 22 inches (entire argillic horizon)
Series control section - The zone from 0 to 60 inches.
The 01/2007 revision changes the moisture regime subclass to ustic-aridic and the subgroup from Typic Haplargids to Ustic Haplargids.