LOCATION COLLBRAN CO+AZ UTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argiustolls
TYPICAL PEDON: Collbran loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 8 inches; brown (7.5YR 5/2) loam, dark brown (7.5YR 3/2) moist; strong fine and medium granular structure; soft, very friable; neutral; clear smooth boundary. (6 to 10 inches thick)
B1--8 to 13 inches; reddish brown (5YR 5/3) clay loam, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure parting to moderate medium granular; slightly hard, very friable, slightly sticky and slightly plastic; thin patchy clay films on peds and in root channels; neutral; clear smooth boundary. (3 to 8 inches thick)
B21t--13 to 18 inches; reddish brown (5YR 5/4) light clay, reddish brown (7.5YR 5/4) moist; moderate medium prismatic structure parting to strong medium angular blocky; hard, firm, sticky and plastic; moderate nearly continuous clay films on peds and in root channels; calcareous; moderately alkaline; gradual wavy boundary. (2 to 10 inches thick)
B22t--18 to 26 inches; reddish brown (5YR 5/4) light clay, reddish brown (7.5YR 5/4) moist; moderate medium prismatic structure parting to strong medium angular blocky; hard, firm, sticky and plastic; moderate nearly continuous clay films on peds and in root channels; calcareous; moderately alkaline; gradual wavy boundary. (2 to 10 inches thick)
B3tca--26 to 34 inches; light brown (7.5YR 6/4) heavy clay loam, brown (7.5YR 5/4) moist; weak medium prismatic structure parting to weak medium and coarse subangular blocky; hard, friable, sticky and plastic; few thin patchy clay films on peds and in root channels; visible secondary calcium carbonate as soft masses and in seams; 5 percent basalt pebbles; calcareous; moderately alkaline; gradual wavy boundary. (5 to 10 inches thick)
Cca--34 to 60 inches; light brown (7.5YR 6/4) gravelly heavy clay loam, brown (7.5YR 5/4) moist; massive; very hard, firm, sticky and plastic; 25 percent basalt pebbles, visible secondary calcium carbonate as soft masses and in seams and as coatings on pebbles; calcareous; moderately alkaline.
TYPE LOCATION: Mesa County, Colorado; SW 1/4 of Sec. 35, T. 19 S., R. 95 W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 7 to 16 inches thick and extends into the B2t horizon in some pedons. Depth to the base of the argillic horizon is 15 to 40 inches. Rock fragments range from 0 to 15 percent in the solum and 15 to 35 percent in the part of the C horizon that is within the series control section. Rock fragments are mainly of pebbles or cobbles. Depth to calcareous material is 10 to 30 inches and depth to the ca horizon is 15 to 40 inches.
The A horizon has hue of 2.5YR through 7.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3.
The B2t horizon has hue of 2.5YR or 5YR, value of 3 through 6 dry, 2 through 5 moist, and chroma of 2 through 6. It is heavy clay loam or clay and the clay content is 35 to 50 percent.
The Cca horizon has hue of 2.5YR through 7.5YR. It is gravelly heavy clay loam or gravelly clay and averages 35 to 50 percent clay in the fine earth fraction. Visible secondary calcium carbonate accumulations occur as nodules, concretions, seams and streaks.
COMPETING SERIES: These are the Ashfork, Blackpipe, Boneek, Chapin, Emigrant, Huggins, Kube, Loma, Nunn, Rednun, Richfield, Ryus, Savo, Sofia, Thunderbird, Torreon, and Wormser series. Ashfork, Blackpipe, Chapin, Emigrant, Thunderbird, and Wormser soils have either a lithic or paralithic contact at a depth of 20 to 40 inches. Boneek, Loma, and Rednun soils have less than 35 percent clay in the lower part of the series control section. Huggins, Kube, Nunn, Richfield, Ryus, Sofia, Savo, and Torreon soils have hue of 7.5YR or yellower in the B2t horizons.
GEOGRAPHIC SETTING: The Collbran series are on alluvial fans, valley side slopes, colluvial mountain slopes, and old terrace levels. Slopes are 0 to 30 percent. The soils formed in thick, calcareous, transported materials derived mainly from basalt and sedimentary rocks. At the type location the average annual precipitation is 16 inches. Mean annual temperature is 46 degrees F, mean summer temperature is 66 degrees F. The frost-free season is 120 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Peninsula, Scholle, and Ildefonso soils. Peninsula soils have a frigid temperature regime and lack a ca horizon, Schole and Ildefonso soils have an aridic moisture regime. Also, Ildefonso soils have a loamy-skeletal control section and Scholle soils have a fine-loamy control section.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used principally for grazing and as irrigated cropland. Native vegetation is mainly sagebrush, western wheatgrass, junegrass, and bluegrasses.
DISTRIBUTION AND EXTENT: Western Colorado and southern Utah. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Western Colorado Reconnaissance, 1939.
REMARKS: Last updated by the state 7/77.