LOCATION ROBOZO UTTentative Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Typic Petrocalcids
TYPICAL PEDON: Robozo silt loam, rangeland. (Colors are for dry soils unless otherwise noted.)
A1--0 to 2 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; moderate medium platy structure that parts to moderate thin platy; slightly hard, friable, plastic; few very fine and common fine roots; many fine and common medium vesicular pores; 10 percent gravel, 5 percent cobbles within horizon and on surface, strongly effervescent; very strongly alkaline (pH 9.2); clear smooth boundary. (2 to 4 inches thick)
A2--2 to 5 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; weak thick platy structure that parts to weak fine granular; slightly hard, firm, moderately sticky and moderately plastic; few very fine and common fine roots; many very fine irregular pores; 5 percent gravel; strongly effervescent; very strongly alkaline (pH 9.2); clear smooth boundary. (3 to 7 inches thick)
Bk1--5 to l4 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure that parts to moderate fine subangular blocky; slightly hard, friable, slightly sticky and moderately plastic; few very fine and common fine roots; few very fine tubular pores; 5 percent gravel, strongly effervescent, carbonates are disseminated; strongly alkaline, strongly saline (pH 9.0); clear smooth boundary. (4 to 9 inches thick)
Bk2--l4 to 28 inches; very pale brown (10YR 8/2) silt loam, pale brown (10YR 6/3) moist; massive; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and few fine tubular pores; 5 percent gravel, strongly effervescent, carbonates are disseminated; strongly alkaline, strongly saline (pH 8.7); gradual irregular boundary. (12 to 14 inches thick)
Bk3--28 to 38 inches; very pale brown (10YR 8/2) silt loam, pale brown (10YR 6/3) moist; massive; slightly hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; common very fine tubular and irregular pores; 5 percent gravel size hardpan fragments, strongly effervescent, carbonates are disseminated; strongly alkaline, strongly saline (pH 8.7); gradual wavy boundary. (8 to 10 inches thick)
Bkm--38 inches; degrading indurated petrocalcic hardpan.
TYPE LOCATION: Beaver County, Utah; about 1.5 miles south of the Beaver-Millard County line and 2.5 miles east of Utah Highway 257, .3 miles south and .3 miles west of the NE corner of Section 14, T. 26 S., R. 10 W.; Read USGS Quad; latitude 38 degrees 33 minutes 10.00 seconds North and longitude 112 degrees 56 minutes 27.00 seconds West, NAD 27
RANGE IN CHARACTERISTICS:
Soil Moisture: The soils are dry for more than 75 percent of the time that the soil temperature is above 41 degrees F. Typic aridic soil moisture regime.
Mean annual soil temperature: 50 to 52 degrees F
Depth to the petrocalcic: 20 to 40 inches.
Particle-size control section (weighted average):
Clay content: 18 to 35 percent.
Rock fragments: 0 to 10 percent.
A horizons:
Hue: 10YR or 7.5YR.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3.
Reaction: Strongly alkaline or very strongly alkaline.
Bk horizons:
Hue: 10YR or 7.5YR.
Value: 6 to 8 dry, 4 to 8 moist.
Chroma: 1 to 4.
Texture: Silt loam or silty clay loam.
Clay content: 18 to 35 percent.
EC (mmhos/cm): 16 to 32.
Reaction: Strongly alkaline or very strongly alkaline.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Robozo soils occur on gently sloping alluvial fans and lake terraces at elevations of 4,900 to 5,100 feet. Slope ranges from 0 to 3 percent. These soils in alluvium and lacustrine deposits derived dominantly from mixed igneous and sedimentary rocks. The average annual precipitation ranges from 7 to 8 inches and the mean annual air temperature ranges from 48 to 50 degrees F. The freeze-free period is 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bandag, Drum, Turley, Saltair and Uvada soils. All of these soils lack a petrocalcic horizon and are very deep to bedrock. Bandag soils have a moisture regime that borders xeric. Saltair soils have a high water table and salic horizons. Uvada soils have a natric horizon.
DRAINAGE AND PERMEABILITY: Well drained; low runoff; moderately slow permeability.
USE AND VEGETATION: Used mainly for rangeland and wildlife habitat. Vegetation is dominantly shadscale, cheatgrass, squirreltail and budsage.
DISTRIBUTION AND EXTENT: Southwestern Utah. These soils are not extensive. The name is coined.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES PROPOSED: Beaver County, (Beaver County Western Part Area), Utah.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from the surface to 5 inches. (A1 and A2 horizons)
Petrocalcic horizon: Indurated hardpan beginning at 38 inches. (Bkm horizon)
The classification is based on the "Keys to Soil Taxonomy, Tenth Edition, 2006".