LOCATION VEGA UTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Haplustolls
TYPICAL PEDON: Vega clay loam, rangeland. (Colors are for moist soil unless otherwise noted.)
A1--0 to 4 inches; very dark grayish brown (10YR 3/2) clay loam, dark grayish brown (10YR 4/2) dry; weak medium platy structure parting to moderate medium granular; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium roots; many fine pores; moderately calcareous; slightly alkaline (pH 7.7); gradual wavy boundary. (3 to 5 inches thick)
A2--4 to 15 inches; dark brown (10YR 3/3) clay loam, dark grayish brown (10YR 4/2) dry; very weak medium prismatic structure; very hard, firm, sticky and plastic; many fine roots; many fine pores; moderately calcareous; slightly alkaline (pH 7.6); gradual wavy boundary. (7 to 12 inches thick)
A3--15 to 30 inches; dark brown (10YR 3/3) clay loam, dark grayish brown (10YR 4/2) dry; weak medium subangular blocky structure; hard, friable, slightly plastic; few large roots; few fine pores; slightly calcareous; slightly alkaline (pH 7.5); clear wavy boundary. (10 to 17 inches thick)
C--30 to 40 inches; dark brown (7.5YR 3/2) clay loam, brown (7.5YR 4/2) dry; massive; hard, friable, sticky and plastic; few large roots; few fine pores; moderately calcareous; slightly alkaline (pH 7.7); clear wavy boundary. (10 to 20 inches thick)
Cy--40 to 60 inches; very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; massive; hard, firm, sticky and plastic; few fine roots; moderately calcareous; few fine pores; numerous veins of gypsum; moderately alkaline (pH 7.9).
TYPE LOCATION: San Juan County, Utah; about 2.2 miles east of the intersection of Highways 160 and U 47; near the southwest corner of sec. 29, T. 38 S., R. 24 E.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon: 20 to 30 inches
Calcium carbonate: Carbonates range from 2 to 15 percent. The soils are calcareous throughout. Generally, there are no discernable layers of carbonate accumulation.
Texture: clay loam that is high in very fine sand or silty clay loam.
Clay content: 28 to 35 percent
Soil moisture: The soil is moist in some parts of the moisture control section 50 to 60 percent of the time that the soil temperature is above 41 degrees F. Aridic ustic moisture regime.
A horizon
Hue: 10YR or 7.5YR
Value: 3 moist and 4 or 5 dry
Chroma: 2 or 3
Organic matter content: 2 to 4 percent
C horizon
Hue: 10YR or 7.5YR
Value: 3 or 4 moist, 4 or 5 dry
Chroma: 2 through 4
Texture: mainly clay loam, that is high in very fine sand, or silty clay loam with strata of loam, and silt loam
Gypsum: veins of gypsum commonly occur below depths of 40 inches.
COMPETING SERIES: These are Ackmen (UT), Alcester (SD), Coleridge (NE), Gabaldon (NM), Hord (NE), Irak (CO), Muir (KS), Roxbury (KS), Shell (NE), Tobin (KS) and Trementia (CO) soils. Ackmen soils have 18 to 27 percent clay in the series control section and are noncalcareous or slightly calcareous. Alcester soils have A horizons 14 to 20 inches thick, have cambic horizons and lacks free carbonates in the series control section. Gabaldon soils have A1 horizons that are mainly 10 to 20 inches thick and have cambic horizons. Hord soils are slightly acid or neutral in the A and Bw horizons to depth of 40 inches, and occur in a higher precipitation zone of 19 to 24 inches. Irak soils have a seasonal water table April through September. Muir soils are medium acid to neutral in the A horizon, have cambic horizons and are noncalcareous throughout. Coleridge, Roxbury, Shell, and Trementia soils are in LRRs G, H and M and are moist in May and June. Tobin soils are noncalcareous above depth of about 27 inches and occur in a higher precipitation zone of 20 to 28 inches.
GEOGRAPHIC SETTING: Vega soils are on narrow valleys of entrenched intermittent streams on flood plains at elevations of 5,800 to 7,000 feet. Slopes are 0 to 6 percent. The soils formed in alluvium derived mainly from igneous and sedimentary rocks, including shale. The mean annual temperature is about 46 to 50 degrees F., and the average annual precipitation is 14 to 18 inches. The average freeze-free period is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Ackmen and Pack soils and the Abajo, Monticello, Shay and Ucolo soils. Abajo, Shay and Ucolo soils are fine particle size class. Monticello soils have argillic horizons with 18 to 27 percent clay.
DRAINAGE AND PERMEABILITY: Moderately well and well drained; slow runoff; slow permeability.
USE AND VEGETATION: Used mainly for rangeland and wildlife habitat. Some areas are dry-farmed and a few areas are used for irrigated alfalfa.
DISTRIBUTION AND EXTENT: Southeastern Utah. The soils of this series are inextensive. MLRA 36.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Juan Area, Utah; 1952.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 30 inches. (A horizons)
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.