LOCATION POLECAT ID
Established Series
Rev. MEJ/ALH/RWL
07/2012
POLECAT SERIES
The Polecat series consists of deep, well drained soils with moderately slow permeability that formed in slope alluvium, colluvium and residuum from lacustrine deposits. Polecat soils have slopes of 4 to 65 percent in foothills. The average annual precipitation is about 14 inches and the average annual temperature is about 51 degrees F.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Calciargidic Argixerolls
TYPICAL PEDON: Polecat silt loam -- on a 11 percent convex west-facing slope at 2,940 feet elevation in rangeland. When described on August 9, 1995, the soil was dry throughout. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak thin platy structure parting to moderate fine granular; soft, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium and coarse roots; many very fine and fine tubular pores; neutral (pH 7.0); clear smooth boundary. (1 to 3 inches thick)
BA--1 to 4 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate thin platy structure parting to moderate fine and medium granular; soft, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium and coarse roots; many very fine and fine tubular pores; neutral (pH 7.0); clear smooth boundary. (3 to 4 inches thick)
Bt--4 to 7 inches; grayish brown (10YR 5/2) silty clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and moderately plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; neutral (pH 7.0); clear wavy boundary. (3 to 6 inches thick)
Btk--7 to 14 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; common faint clay films on faces of peds and in pores; slightly effervescent (about 5 percent CaCO3); calcium carbonate as coats on faces of peds and in veins; slightly alkaline (pH 7.4); clear wavy boundary. (3 to 7 inches thick)
Bk1--14 to 24 inches; very pale brown (10YR 8/2) silt loam, light brownish gray (10YR 6/2) moist; strong medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; few very fine and fine tubular pores; violently effervescent (about 25 percent CaCO3); calcium carbonate is disseminated throughout the peds; moderately alkaline (pH 8.0); clear wavy boundary. (3 to 12 inches thick)
Bk2--24 to 35 inches; light gray (10YR 7/2) silt loam, grayish brown (10YR 5/2) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; strongly effervescent (about 20 percent CaCO3); calcium carbonate is disseminated throughout the peds; 2 inch diameter krotavina filled with grayish brown (10YR 5/2) A and Bt material; slightly alkaline (pH 7.8); gradual wavy boundary. (5 to 15 inches thick)
Bk3--35 to 51 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; slightly effervescent (about 15 percent CaCO3); calcium carbonate is disseminated throughout the peds; slightly alkaline (pH 7.8); gradual wavy boundary. (9 to 20 inches thick)
Crk--51 to 60 inches; very pale brown (10YR 7/3) stratified lacustrine deposits that have less than 5 percent calcium carbonate on horizontal and vertical faces of deposits.
TYPE LOCATION: Ada County, Idaho; about 3.5 miles east and 3.75 miles north of Eagle; about 1,320 feet east and 1,200 feet south of the northwest corner of section 25, T. 5 N., R. 1 E.; USGS Eagle Quadrangle; (Latitude - 43 degrees, 44 minutes, 43 seconds N. and Longitude - 116 degrees, 17 minutes, 07 seconds W.)
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 52 to 54 degrees F.
Thickness of mollic epipedon - 10 to 20 inches
Depth to calcium carbonate - 12 to 20 inches
Depth to paralithic contact - 40 to 60 inches
Particle-size control section - 20 to 35 percent clay; 0 to 5 percent gravel
Moisture control section - moist less than 90 consecutive days when the soil temperature is greater than 47 degrees F.
A and BA horizons
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Clay content - 15 to 20 percent
Rock fragments - 0 to 5 percent gravel
Bt horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Clay content - 27 to 35 percent
Rock fragments - 0 to 5 percent gravel
Reaction - neutral or slightly alkaline
Btk horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - SIL or SICL
Clay content - 20 to 30 percent
Rock fragments - 0 to 5 percent gravel
Calcium carbonate equivalent - 5 to 10 percent
Reaction - slightly alkaline or moderately alkaline
Bk horizon
Value - 6 through 8 dry, 4 through 6 moist
Chroma - 2 or 3 dry or moist
Texture - SIL, L or VFSL
Clay content - 15 to 25 percent
Rock fragments - 0 to 5 percent gravel
Calcium carbonate equivalent - 10 to 30 percent
Salinity - nonsaline or very slightly saline
Reaction - slightly alkaline or moderately alkaline
COMPETING SERIES: These are the
Hamrub,
Kimama and
Marley series. Hamrub soils are 40 to 50 inches deep to a duripan and have 2Bkq horizons. Kimama soils are very deep and have 0 to 20 cemented cicada nodules. Marley soils are deep to a duripan, have Btb and Bkb horizons and have mean annual soil temperature of 47 to 50 degrees F.
GEOGRAPHIC SETTING: Polecat soils are on hill backslopes, footslopes and summits and have slopes of 4 to 65 percent. The soils formed in slope alluvium, colluvium and residuum from lacustrine deposits. The elevation ranges from 2,700 to 3,300 feet. The average annual precipitation is 12 to 15 inches and the average annual temperature is 50 to 52 degrees F. The frost-free period is 140 to 155 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Aldape,
Pawtoot and
Shadoval soils. Aldape soils have an abrupt texture change from the surface to the argillic horizon and are 40 to 60 inches to a duripan. Pawtoot soils are more than 60 inches deep to a paralithic contact and have an abrupt textural change from the soil surface to the argillic horizon. Shadoval soils are 20 to 40 inches deep to a paralithic contact and have vertic properties in the upper 40 inches. These soils all occur on the same landform as the Polecat series.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: Polecat soils are used mainly for rangeland. Natural vegetation is basin big sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Ada County, Idaho. MLRA 10. The soils are of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Ada County, Idaho, 2012.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - zone from the surface to 14 inches (A, BA and Bt1 horizons)
Argillic horizon - zone from 4 to 14 inches (Bt and Btk horizons)
Calcic horizon - zone from 14 to 51 inches (Bk1, Bk2 and Bk3 horizons)
Particle-size control section - zone from 4 to 14 inches
Paralithic contact - at 51 inches (Crk horizon)
Soil moisture regime - aridic bordering on xeric
These soils are drier than other Xerolls in the region under similar precipitation due to early runoff and extended period of high evapotranspiration.
National Cooperative Soil Survey
U.S.A.