LOCATION EVANOT CO
Established Series
Rev. DLM/DAD/SJJ
04/2016
EVANOT SERIES
The Evanot series consists of very deep, well drained soils that formed in eolian deposits and slope alluvium derived from sandstone. Evanot soils are on hills and structural benches. Slopes range from 1 to 25 percent. Mean annual precipitation is about 14 inches and the mean annual temperature is about 44 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Argiustolls
TYPICAL PEDON: Evanot loam , on a east facing, 4 percent slope in dry cropland at an elevation of 6,380 feet. (Colors are for dry soil unless otherwise noted.) When described on June 3, 1977 the soil was moist from 0 to 20 inches and dry below.
Ap--0 to 8 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many very fine and fine roots; few fine tubular pores; slightly alkaline (pH 7.4); abrupt smooth boundary. (8 to 13 inches thick)
Bt1--8 to 20 inches; yellowish brown (10YR 5/4) clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, sticky and plastic; many very fine and fine roots; few fine tubular pores; many distinct clay films on faces of peds ; slightly alkaline (pH 7.4); clear wavy boundary. (12 to 20 inches thick)
Bk1--20 to 33 inches; very pale brown (10YR 7/3) clay loam, brown (10YR 5/3) moist; moderate coarse subangular blocky structure parting to moderate medium subangular blocky; hard, friable, sticky and plastic; few fine roots; few fine tubular pores; calcium carbonate disseminated and as few fine soft seams and threads on faces of peds ; violently effervescent; 12 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); gradual smooth boundary.
Bk2--33 to 42 inches; light yellowish brown (10YR 6/4) loam, brown (10YR 5/3) moist; weak coarse subangular blocky structure parting to moderate medium subangular blocky; hard, friable, sticky and plastic; few fine tubular pores; calcium carbonate disseminated and as few fine soft seams and threads on faces of peds ; violently effervescent; 10 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear smooth boundary.
Bk3--42 to 51 inches; yellowish brown (10YR 5/4) loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine tubular pores; calcium carbonate disseminated and as few fine soft seams and threads on faces of peds ; ; violently effervescent; 10 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); gradual smooth boundary.
Bk4--51 to 65 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; calcium carbonate disseminated and as few fine soft seams and threads on faces of peds ; strongly effervescent; 8 percent calcium carbonate equivalent; moderately alkaline (pH 8.4). (The combined thickness of the Bk horizons ranges from 30 to 40 inches )
TYPE LOCATION: Moffat County, Colorado; about 6 miles south of Craig; located about 2,250 feet north and 100 feet west of the southeast corner of sec. 23, T. 6 N., R. 91 W.; Castor Gulch USGS quad; lat. 40 degrees 27 minutes 43 seconds N. and long. 107 degrees 27 minutes 45 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture regime: Ustic bordering on Aridic; 30 to 45 consecutive days dry during the summer.
Soil temperature regime: frigid
Mean annual soil temperature: 44 to 46 degrees F.
Mean annual summer soil temperature: 59 to 65 degrees F.
Depth to secondary calcium carbonate: 20 to 30 inches
Depth to the base of the argillic horizon: 20 to 30 inches
Thickness of the mollic epipedon: 8 to 13 inches
Particle-size control section (weighted average):
Clay content: 28 to 35 percent
A horizon:
Hue: 10YR or 7.5YR
Value: 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Reaction: neutral or slightly alkaline
Bt horizon:
Hue: 10YR or 7.5YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 2 to 4 dry or moist
Texture: CL, SICL
Clay content: 28 to 35 percent
Sand content: 15 to 30 percent
Reaction: neutral or slightly alkaline
Bk horizon:
Hue: 10YR or 7.5YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 or 4 dry or moist
Texture: L, CL, SICL
Clay content: 18 to 30 percent
Sand content: 15 to 35 percent
Calcium carbonate equivalent: 5 to 15 percent
Exchangeable sodium: 0 to 5 percent
Reaction: moderately alkaline
COMPETING SERIES: These are the
Beavwan,
Berlake,
Crittenden,
Eapa,
Evanston,
Joplin,
Kevin,
Marmarth,
Nuley,
Telstad,
Udecide, and
Varney series. Additional potential competitors are the
Assinniboine,
Bostwick,
Cheesman,
Duffson,
Emlin,
Jarre,
Kenilworth,
Morval,
Notter,
Perrypark,
Peyton,
Reicess,
Sugakool,
Turret, and
Villa Grove series.
Assinniboine and
Kenilworth soils have greater than 30 percent sand in the Bt horizons.
Beavwan,
Sugakool, and
Turret soils have substrata with greater than 35 percent rock fragments.
Berlake,
Bostwick,
Cheesman,
Jarre, and
Peyton soils have lime below 30 inches or are noncalcareous throughout
Crittenden, and
Duffson soils have a lithic contact.
Eapa and
Reicess soils have moisture control sections that are moist in most parts
May through July
Emlin and
Morval soils have calcic horizons
Evanston,
Kevin,
Telstad, and
Varney soils have secondary carbonate within a depth of 20 inches
Joplin soils have gypsum at a depth of 24 to 60 inches
Marmarth, and
Udecide soils have paralithic contact at a depth of 20 to 40 inches
Notter soils have rock fragments in the Bt horizon
Nuley soils have a lithic contact at a depth of 40 to 60 inches
Perrypark soils have hue redder than 7.5YR
Villa Grove soils have exchangeable sodium in the Bt horizons
GEOGRAPHIC SETTING:
Parent material: eolian deposits and slope alluvium derived from sandstone.
Landform: hills and structural benches.
Slopes: 1 to 25 percent
Elevation: 6,200 to 7,600 feet
Mean annual air temperature: 42 to 45 degrees F.
Mean annual precipitation: 13 to 16 inches.
Wettest months: Precipitation is relatively evenly distributed throughout the year.
Frost-free period: 70 to 95 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Abor and
Hesperus series. Abor soils are in a fine family and are on similar landforms. Hesperus soils have mollic epipedons greater than 20 inches thick and are on northerly aspects.
DRAINAGE AND PERMEABILITY: Well drained, medium to high runoff, moderately slow permeability.
USE AND VEGETATION: These soils are used for dryland farming, rangeland, and wildlife habitat. Vegetation consists of bluebunch wheatgrass, needleandthread , mutton grass, western wheatgrass, prairie junegrass, basin wildrye, Wyoming big sagebrush, mountain snowberry, and low rabbitbrush.
DISTRIBUTION AND EXTENT: Northwest Colorado. LRR E, MLRA 34. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Moffat County, Colorado. 1991.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 8 inches. (A horizon)
Argillic horizon: The zone from 8 to 20 inches. (Bt horizon)
Keys to Soil Taxonomy: 7th edition, 1996
CEC activity class is estimated. Calcium carbonate equivalent was determined at the project office using the calcimeter method.
ADDITIONAL DATA:
National Cooperative Soil Survey
U.S.A.