LOCATION BENJAMIN UTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Fluvaquentic Haplustolls
TYPICAL PEDON: Benjamin silty clay, cultivated. (Colors are for air dry soil unless otherwise noted.)
Ap1--0 to 1 inches; grayish brown (10YR 5/2) silty clay, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; hard, very firm, sticky, plastic; few very fine roots; strongly calcareous, lime is disseminated; moderately alkaline (pH 8.0); clear smooth boundary. (1 to 2 inches thick)
Ap2--1 to 4 inches; grayish brown (10YR 5/2) silty clay, very dark grayish brown (10YR 3/2) moist; moderate fine and very fine angular blocky structure; very hard, very firm, sticky, very plastic; common fine and very fine roots; few fine and very fine pores; strongly calcareous; lime is disseminated; moderately alkaline (pH 8.2); there are cracks 3/8 to 1 inch wide in this horizon, but they do not extend below; clear smooth boundary. (3 to 5 inches thick)
A--4 to 17 inches; grayish brown (10YR 5/2) silty clay, very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure that parts to moderate medium angular blocky structure; very hard, very firm, sticky, very plastic; common very fine roots; common very fine and few fine pores; strongly calcareous, lime disseminated; strongly alkaline (pH 8.6); gradual wavy boundary. (12 to 15 inches thick)
Cg1--17 to 25 inches; gray (10YR 6/1) silty clay, dark gray (10YR 4/1) moist; many distinct mottles of grayish brown (2.5Y 5/2), brown (7.5YR 5/4) and very dark gray (10YR 3/1); massive; very hard, very firm, sticky, very plastic; few very fine roots; common very fine pores; strongly calcareous, lime disseminated; strongly alkaline (pH 8.6); gradual wavy boundary. (8 to 14 inches thick)
Cg2--25 to 38 inches; gray (10YR 6/1) silty clay, dark gray (10YR 4/1) moist; few fine distinct brown (7.5YR 4/4); many distinct reddish brown (5YR 4/3), and brown (10YR 5/3) mottles; massive; very hard, very firm, sticky, very plastic; few very fine roots; few very fine pores; strongly calcareous, lime disseminated; strongly alkaline (pH 8.6); gradual wavy boundary. (10 to 15 inches thick)
Cg3--38 to 46 inches; pink (7.5YR 7/3) silty clay loam, brown (7.5YR 4/3) moist; common medium prominent yellowish brown (10YR 5/4) and yellowish red (5YR 4/6) moist; common medium prominent yellowish brown (10YR 5/4) and yellowish red (5YR 4/6) mottles; massive; hard, firm, slightly sticky, plastic; strongly calcareous, lime disseminated; moderately alkaline (pH 8.4); clear smooth boundary. (0 to 10 inches thick)
Cg4--46 to 52 inches; light brown (7.5YR 6/3) silty clay, brown (7.5YR 4/3) moist, common medium prominent yellowish brown (10YR 5/6) mottles; massive; very hard, very firm, sticky, very plastic; strongly calcareous, lime disseminated; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 8 inches thick)
2C--52 to 60 inches; light brown (7.5YR 6/3) sandy loam, brown (7.5YR 4/3) moist; few medium prominent yellowish brown (10YR 5/6) mottles; massive; soft, very friable, nonsticky, nonplastic; strongly calcareous, lime disseminated; moderately alkaline (pH 8.0).
TYPE LOCATION: Utah County, Utah; about 1 1/2 miles north of Lakeshore on the Lakeshore-Benjamin Road, and about 650 feet west of the road in a cultivated field; 330 feet south and 650 feet west of the NE corner of sec. 8, T.8S., R.2E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature at about 20 inches is 47 degrees to 54 degrees F. This soil is dry in some part of the 7 to 20 inches depth for 90 consecutive days but is not dry in all parts for 60 consecutive days.
The mollic epipedon is less than 20 inches thick and organic matter decreases irregularly or remains above 0.5 percent to depth of 50 inches. Depth to water table ranges from 30 to 60 inches. This soils has chroma of 1 if not mottled, or if mottled chroma of 2 or less at some depth between 20 and 40 inches. Lime content ranges from 15 to 30 percent. The soils are moderately to strongly alkaline and are slightly to strongly saline. The 10 to 40 inch particle size control section is clay, or silty clay, with more than 35 percent clay.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 through 3.
The C horizon has hue of 10YR, 7.5YR or 5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 through 3. Some pedons have layers of silt loam or coarser material, more than 12 inches thick, at depths of 38 to 50 inches.
COMPETING SERIES: These are the Hussman, Jura, Pack, Salt Lake, Shay, and Ucolo series. Hussman soils are mottled within 20 inches, noncalcareous in surface and have less than 15 percent lime in the C horizon. Jura soils are slightly calcareous, and lack subsurface mottling. Pack, and Shay soils have mollic epipedons more than 20 inches thick. Also, Pack soils have less than 35 percent clay. Salt Lake soils are poorly drained, have chroma of 1, are carbonatic and have calcic horizons. Ucolo soils lack characteristics of wetness within 40 inches.
GEOGRAPHIC SETTING: Benjamin soils are on nearly level and gently undulating flood plains on slopes of 0 to 1 percent. They formed in fine textured alluvium derived mainly from shale. Benjamin soils occur in a dry subhumid continental climate, have mean annual temperature of 49 degrees to 51 degrees F., mean summer temperature of about 70 degrees F., and average annual precipitation of 14 to 16 inches. The frost-free period ranges from 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cache and Kirkham soils. Cache soils have salic horizons and lack a mollic epipedon. Kirkham soils are clay loam or silty clay loam containing less than 35 percent clay in the control section.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; slow permeability.
USE AND VEGETATION: Used as irrigated cropland for barley, alfalfa, sugar beets, corn and pasture. Native vegetation is greaswood, salt grass, foxtail and weeds.
DISTRIBUTION AND EXTENT: Central Utah. These soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Utah County (Central Utah County Area), Utah, 1971.