LOCATION DOMINGUEZ COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Haplusterts
TYPICAL PEDON: Dominguez clay loam - grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; brown (7.5YR 5/3) clay loam, dark brown (7.5YR
4/3) moist; moderate fine granular structure; soft, very friable; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (4 to 6 inches thick)
Bw1--5 to 9 inches; reddish brown (5YR 5/3) heavy clay loam, reddish brown (5YR 4/3) moist; weak coarse prismatic structure parting to moderate medium angular blocky; hard and extremely hard, very friable; cracks 1/4 to 1/2 inch wide when dry; few shiny patches on vertical faces of peds; strongly effervescent, moderately alkaline (pH 8.4); clear smooth boundary. (3 to 6 inches thick)
Bw2--9 to 25 inches; reddish brown (5YR 5/3) clay, reddish brown
(5YR 4/3) moist; moderate very coarse prismatic structure parting to moderate coarse angular blocky; extremely hard, very plastic; few wax- like patches presumed to be silicate clay on vertical faces of peds; cracks 1/2- to 1-inch wide when dry; many slickensides; strongly effervescent, moderately alkaline (pH 8.4); gradual wavy boundary. (8 to 20 inches thick)
Bk1--25 to 35 inches; reddish brown (5YR 5/3) clay, reddish brown (5YR 4/3) moist; weak very coarse angular blocky structure; extremely hard, very plastic; cracks 1/2- to 1-inch wide when dry; some visible secondary calcium carbonate accumulations as concretions, thin seams, and streaks; violently effervescent, moderately alkaline (pH 8.4); gradual wavy boundary. (8 to 14 inches thick)
Bk2--35 to 47 inches; light reddish brown (5YR 5/3) clay, reddish brown (5YR 5/3) moist; massive; extremely hard, very plastic; cracks 1/2- to 1-inch wide when dry; some visible secondary calcium carbonate accumulations as concretions, thin seams, and streaks; violently effervescent, moderately alkaline (pH 8.4).
TYPE LOCATION: Mesa County, Colorado; NW1/4 of Sec. 20, T. 11 S., R. 102 W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 47 to 58 degrees F., and mean summer soil temperature ranges from 60 to 78 degrees F. Thickness of sola ranges from 15 to 30 inches. The weighted average content of organic carbon in the upper 15 inches is approximately .7 percent. The sand/clay ratio is less than 1. Cation exchange capacity ranges from 60 to 90 milliequivalents per 100 grams of clay. The particle-size control section is typically clay or clay loam, and clay ranges from 35 to 50 percent, silt from 15 to 40 percent, and sand from 15 to 45 percent, with more than 15 percent but less than 35 percent being fine or coarser sand. Rock fragments range from 0 to 15 percent, but are commonly less than 5 percent. These soils are usually moist in some part between depths of 4 and 12 inches for more than 1/4 but less than 1/2 of the time the soil temperature exceeds 41 degrees F. and are usually moist in all parts between depths of 4 and 12 inches for less than 60 cumulative days during the 120 days following the winter solstice.
The A horizon has hue of 7.5YR through 2.5YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3. When the surface horizon value is as dark as 5 dry and 3 moist, the horizon is too thin or has too little organic matter to qualify as a mollic epipedon. This horizon is moderately or strongly alkaline (pH 8.0 to 8.6). Typically, it has fine granular primary structure but has subangular blocky structure in some pedons. It is slightly hard or soft.
The Bw horizon has hue of 5YR or 2.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 3 or 4. Typically, the horizon has coarse prismatic primary structure that parts to angular blocky, but the prismatic structure is weak in some pedons. It is moderately or strongly alkaline (pH 8.0 to 8.6). This horizon has redder hue or brighter chroma than the overlying and underlying horizons or it has moderate grade of structure overlying a continuous horizon of secondary carbonate accumulation.
The Bk horizon has hue of 5YR or 2.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 or 3. It has 4 to about 12 percent calcium carbonate equivalent. Reaction is moderately or strongly alkaline.
COMPETING SERIES: These are the Bumbob(T), Denby, Heldt, Littlenan, and Lockerby series. Bumbob soils have hue yellower than 7.5YR. Denby soils have SAR values of 9 to 24 and hues of 7.5YR and yellower in the subsurface horizons. Heldt soils have hue of 5Y through 10YR in the cambic horizon. Littlenan and Lockerby soils have a paralithic contact above 40 inches.
GEOGRAPHIC SETTING: Dominguez soils are on alluvial fans, toe slopes, and valley side slopes. Slopes range from 0 to 10 percent. The soil formed in fine-textured, calcareous, alluvial fan sediments weathered from reddish brown calcareous shales of the Morrison formation. Elevation ranges from 5,000 to 6,500 feet. The mean annual precipitation ranges from 12 to 15 inches. Mean annual temperature ranges from 46 to 52 degrees F., and the mean summer temperature ranges from 62 to 75 degrees F. The frost-free period is about 100 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gibbler and Loma soils. Gibbler soils have a lithic contact at depths of 20 to 40 inches and Loma soils have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used principally for native pastureland. Native vegetation consists of black sage, big sage, western wheatgrass, Indian ricegrass, and scattered greasewood.
DISTRIBUTION AND EXTENT: The western slope area of Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Mesa County (Lower Colorado Area), Colorado, 1970.