LOCATION POMAT UTEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, active, calcareous, mesic Typic Xerorthents
TYPICAL PEDON: Pomat silt loam--nonirrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 5 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; few fine pores; strongly effervescent; moderately alkaline (pH 8.2) clear smooth boundary. (5 to 8 inches thick)
A--5 to 10 inches; light brownish gray (10YR 6/2) silt loam, grayish brown (10YR 5/2) moist; weak medium subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; few fine and medium pores; strongly effervescent; moderately alkaline (pH 8.2); clear irregular boundary. (0 to 5 inches thick)
C1--10 to 25 inches; pale yellow (2.5Y 8/2) silt loam, light brownish gray (2.5Y 6/2) moist; massive; hard, friable, slightly sticky and slightly plastic; few fine pores; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 20 inches thick)
C2--25 to 56 inches; pale yellow (2.5Y 8/2) silt loam, light yellowish brown (2.5Y 6/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few fine pores; violently effervescent; very strongly alkaline (pH 9.2); clear wavy boundary. (20 to 35 inches thick)
2C3--56 to 65 inches; very pale brown (10YR 8/2) fine sandy loam, pale brown (10YR 6/3) moist; massive; soft, very friable, nonsticky and nonplastic; violently effervescent; very strongly alkaline (pH 9.2).
TYPE LOCATION: Box Elder County, Utah; about 2 miles west and 2 miles north of the Valley exit from Interstate 84 in Blue Creek Valley; approximately 1,000 feet south and 600 feet east of the northwest corner of section 18, T. 13 N., R. 5 W.; USGS Howell 7.5 minute topographic quadrangle; 41 degrees 51 minutes 55 seconds north latitude and 112 degrees 28 minutes 25 seconds west longitude, NAD27; UTM zone 12N 377639E, 4635874N, NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture - The moisture control section is moist for 60 to 70 consecutive days during the winter months and is dry for 60 to 90 consecutive days in the summer months; Xeric moisture regime that borders on aridic.
Mean annual soil temperature - 48 to 54 degrees F.
Ochric epipedon thickness - 5 to 13 inches.
Particle-size control section - Clay content: 12 to 17 percent.
A horizons - Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 1.0 or 2.0 percent in the upper 15 inches, and decreases regularly to a depth of 50 inches.
Reaction: Moderately alkaline or strongly alkaline.
Effervescence: Slightly effervescent to violently effervescent.
C horizons - Hue: 10YR through 5Y.
Value: 7 or 8 dry, 5 through 7 moist.
Chroma: 2 through 4, dry or moist.
Consistence: Hard to very hard dry in horizons above 40 inches.
Reaction: Strongly alkaline or very strongly alkaline (up to pH 9.6).
Sodicity (SAR): 5 to 40.
Calcium carbonate equivalent: 15 to 30 percent.
Other features: Exchangeable sodium percentage (ESP) is more than 15 percent within 40 inches of the soil surface.
COMPETING SERIES: There are currently no other series in this family.
GEOGRAPHIC SETTING: Pomat soils are on lake plains, intermediate-level and high-level lake terraces, and escarpments of terraces. These soils formed in lacustrine deposits derived from mixed sources and alluvium derived from limestone and sandstone. Slopes are 1 to 40 percent. Elevations range from 4,600 to 5,400 feet. The climate is dry subhumid. The mean annual precipitation is 12 to 14 inches, the mean annual temperature is 46 to 52 degrees F., and the frost-free period is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hansel, Kearns, Kessler, Parleys, Red Rock, Taylorsflat, Thiokol, and Timpanogos soils. Hansel, Taylorsflat, and Thiokol soils have calcic horizons. Also, Hansel soils have argillic horizons and Thiokol soils have cambic horizons. Kessler soils have more than 40 percent calcium carbonate equivalent. Kearns and the Red Rock soils have mollic epipedons and cambic horizons. Parleys, Timpanogos and Kearns soils have mollic epipedons, argillic horizons, and calcic horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium to very high surface runoff; moderate or moderately slow permeability.
USE AND VEGETATION: About 75 percent of Pomat soils are used for dry cropland and the other 25 percent is used as rangeland. The native vegetation is dominantly Wyoming big sagebrush, mountain big sagebrush, and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Northwestern Utah. These soils are moderately extensive. MLRA 28A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Box Elder County (East Box Elder Area), Utah, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 10 inches (Ap and A horizons).
Particle-size control section - The zone from 10 to 40 inches (C1 horizon and part of the C2 horizon).
The active cation exchange activity class was added to the taxonomic classification in December 2002 based on soil property data.
ADDITIONAL DATA: The typical pedon at the series type location has partial characterization data by the Soils Laboratory from Utah State University (USU) Logan, UT and is published on pages 214-215, Table 9 of the Soil Survey of Box Elder County, Utah, Eastern Part.