LOCATION POLECREEK IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Lithic Ultic Argixerolls
TYPICAL PEDON: Polecreek very gravelly loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 4 inches; brown (10YR 5/3) very gravelly loam, dark brown (10YR 3/3) moist; weak thin platy structure parting to moderate very fine and fine granular; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; many fine irregular pores; slightly acid (pH 6.2); clear smooth boundary. (3 to 5 inches thick)
A2--4 to 9 inches; brown (10YR 5/3) very cobbly loam, dark brown (7.5YR 3/2) moist; moderate fine and medium subangular blocky structure parting to moderate fine granular; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine tubular pores; 25 percent cobbles and 10 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (4 to 6 inches thick)
Bt--9 to 18 inches; light brown (7.5YR 6/4) very cobbly clay, dark reddish brown (5YR 3/4) broken and brown (7.5YR 4/4) rubbed moist; moderate medium and coarse prismatic structure parting to moderate fine and medium subangular blocky; very hard, very firm, very sticky and very plastic; common very fine and fine roots on faces of peds; many very fine and fine tubular pores; continuous distinct clay films on faces of peds and in pores; 40 percent cobbles and 15 percent pebbles; slightly acid (pH 6.4); abrupt broken boundary. (4 to 10 inches thick)
R--18 to 21 inches; slightly decomposed basalt bedrock; exterior is brown (7.5YR 5/4) dry and dark brown (7.5YR 3/4) moist; interior is dark gray (N 4/) dry and very dark gray (N 3/) moist; few moderately thick silica coatings in cracks in bedrock.
TYPE LOCATION: Camas County, Idaho; about 2 miles east and 7 miles south of Fairfield; 2,280 feet west and 1,860 feet south of the northeast corner sec. 23, T. 2 S., R. 14 E.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 7 to 16 inches
Average annual soil temperature - 42 to 46 degrees F.
Depth to bedrock - 10 to 20 inches
Base saturation - 50 to 75 percent
Reaction - slightly acid to neutral
A horizon
Hue - 7.5YR or 10YR
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Bt horizon
Hue - 5YR to 10YR
Value - 4 to 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - CBV-C, CBV-CL, CBV-SICL, GRV-C, or CBX-CL
Clay content - 35 to 60 percent
Rock fragment content - 35 to 60 percent
Some pedons have Btb horizon
COMPETING SERIES: There are no other series in this family. Closely related soils are Arling, Gaib, Shepan, and Snell. Arling soils have less than 35 percent coarse fragments. Gaib soils have a loamy-skeletal particle-size control section. Shepan and Snell soils are pachic.
GEOGRAPHIC SETTING: Polecreek soils are on hills and basalt plains. They formed in loess and residuum weathered from rhyolite or basalt. Slopes are 0 to 60 percent. Elevations are 4,500 to 6,500 feet. The average annual precipitation is 12 to 16 inches. Average annual temperature is 40 to 45 degrees F. The frost-free season is 60 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Elkcreek, Gaib, Harmehl, Harahill, Laurentzen, and Mulshoe soils. Elkcreek and Mulshoe soils are moderately deep to bedrock. Harmehl and Harahill soils have a fine loamy control section and are moderately deep to bedrock. Laurentzen soils have a fine loamy control section and are over 40 inches to bedrock. Gaib soils have less than 35 percent clay in the control section. Elkcreek and Gaib soils occur on mountains and foothills. Harmehl, Harahill, and Laurentzen soils are on basalt plains.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; very slow permeability.
USE AND VEGETATION: These soils are used as rangeland. Vegetation is bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass, squirreltail, and alkali sagebrush.
DISTRIBUTION AND EXTENT: Polecreek soils are inextensive in southwest and south central Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Camas County, Idaho, 1975.
REMARKS: Diagnostic horizon and features recognized in this series are:
Mollic epipedon - the zone from the surface of the soil to approximately 9 inches (A1 and A2 horizons)
Argillic horizon - the zone from approximately 9 to 18 inches (Bt horizon)
Lithic contract - at approximately 18 inches
Ultic Argixerolls feature - base saturation 50 to 75 percent in some part between 25 and 75 cm.