LOCATION POKEY ID+WY

Established Series
Rev. SHB/BDG/EMM
07/2013

POKEY SERIES

The Pokey series consists of very deep, somewhat poorly drained soils on low stream terraces and floodplains. They formed in alluvium from mixed sources. Permeability is moderate in the solum and rapid in the substratum. Slope ranges from 0 to 4 percent. The average annual precipitation is about 40 inches and the average annual air temperature is about 44 degrees F.

TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, isotic, frigid Vitrandic Humixerepts

TYPICAL PEDON: Pokey ashy loam, pasture; on a 1 percent slope at 2,750 feet elevation. When described on November 3, 1983, the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)

A1--0 to 10 inches; grayish brown (10YR 5/2) ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots; many very fine and fine tubular pores; 5 percent gravel; strongly acid (pH 5.5); gradual wavy boundary. (3 to 10 inches thick)

A2--10 to 15 inches; grayish brown (10YR 5/2) ashy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine tubular pores; 5 percent gravel; strongly acid (pH 5.5); gradual wavy boundary. (4 to 10 inches thick)

Bw--15 to 23 inches; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; common fine distinct brown (7.5YR 4/2) redox depletions and strong brown (7.5YR 5/6) moist redox concentrations; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; 5 percent gravel; strongly acid (pH 5.3); gradual wavy boundary. (0 to 12 inches thick)

Cg1--23 to 27 inches; light gray (10YR 7/2) very fine sandy loam, grayish brown (10YR 5/2) moist; many medium prominent strong brown (7.5YR 5/6) moist redox concentrations; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few very fine and fine roots; common very fine and fine tubular pores; common very fine mica flakes; 5 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary. (2 to 9 inches thick)

2Cg2--27 to 34 inches; light brownish gray (2.5Y 6/2) loamy sand, dark grayish brown (2.5Y 4/2) moist; many medium distinct and prominent light olive brown (2.5Y 5/6) and strong brown (7.5YR 5/6) moist redox concentrations; single grain; loose, nonsticky and nonplastic; many fine and medium interstitial pores; common very fine mica flakes; few very fine iron and manganese concretions; 10 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary. (6 to 13 inches thick)

2Cg3--34 to 62 inches; light gray (5Y 7/1) coarse sand, gray (5Y 5/1) moist; many medium prominent light olive brown (2.5Y 5/6) and strong brown (7.5YR 5/6) moist redox concentrations; single grain; loose, nonsticky and nonplastic; many fine and medium interstitial pores; common very fine mica flakes; few very fine iron and manganese concretions; 10 percent gravel; slightly acid (pH 6.4).

TYPE LOCATION: Shoshone County, Idaho; about 4.5 miles northwest of Clarkia, about 50 feet south and 1,300 feet west of the northeast corner of sec. 22, T. 43 N., R. 1 E.

RANGE IN CHARACTERISTICS:

Average annual soil temperature - 43 to 45 degrees F
Average summer soil temperature - 55 to 57 degrees F without an O horizon
Solum thickness - 18 to 36 inches
Umbric epipedon thickness - 10 to 20 inches
Depth to seasonal high water table - 18 to 30 inches (February to June); (July to January - 30 to >60 inches)

Volcanic glass content in the 0.02 to 2.0 mm fraction - 5 to 20 percent (estimated)
Acid-oxalate extractable Al plus 1/2 Fe - 0.4 to 1.0 percent (estimated)
Moist bulk density - 1.0 to 1.2 g/cc

A horizon
Value - 4 or 5 dry, 2 or 3 moist
Texture - ashy loam or ashy silt loam
Gravel - 0 to 5 percent
Reaction - strongly acid to slightly acid

Bw horizon - absent in some pedons
Texture - loam or silt loam
Gravel - 0 to 5 percent
Reaction - strongly acid to slightly acid

Bg horizon - present in some pedons
Value - 6 or 7 dry, 4 or 5 moist
Mottles - contrast of distinct or prominent, hue of 7.5YR, value of 4 or 5 moist, chroma of 2 to 6 moist
Texture - loam or silt loam
Gravel - 0 to 5 percent
Reaction - moderately acid or slightly acid

Cg horizon
Hue - 10YR or 2.5Y
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 1 or 2, dry or moist
Mottles - contrast of distinct or prominent, value of 4 or 5 moist, chroma of 2 to 6 moist
Texture - very fine sandy loam, loam or silt loam
Gravel - 0 to 5 percent
Reaction - moderately acid or slightly acid

2Cg horizon
Hue - 2.5Y, 5Y, or 5GY
Mottles - value of 4 or 5 moist, chroma of 4 to 6 moist
Texture - loamy sand, sand, or coarse sand
Coarse fragments - 10 to 35 percent
Reaction - moderately acid to neutral

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Pokey soils are on low stream terraces and floodplains. Slopes range from 0 to 4 percent. These soils formed in alluvium from mixed sources. Elevation ranges from 2,200 to 3,100 feet. The average annual air temperature ranges from 43 to 45 degrees F. and average annual precipitation is 35 to 45 inches. The average frost-free period is from 80 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Helmer and Clarkia soils and the similar Miesen soils. Miesen soils are on higher positions of the floodplain. Helmer soils are on higher dissected terraces and toeslopes and have a fragipan at depths of 10 to 20 inches. Clarkia soils are on low stream terraces and are poorly drained and fine-silty.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderate permeability in the solum and rapid or very rapid in the substratum. These soils are occasionally flooded for brief periods of time between February and May when streams overflow.

USE AND VEGETATION: These soils are used for hay and pasture, wildlife habitat, and recreation. Potential natural vegetation is mainly semi-wet meadow grasses, forbs, and sedges with Douglas hawthorn, western river alder, pacific willow, western thimbleberry, common ladyfern, and Rocky Mountain iris.

DISTRIBUTION AND EXTENT: Northern Idaho. This soil is not extensive. MLRA 43A.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Benewah County, Idaho, 1975.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Umbric epipedon - the zone from the soil surface to 15 inches (A1 and A2 horizons)

Cambic horizon - the zone from 15 to 23 inches (Bw horizon)

Particle-size control section - the zone from 10 to 40 inches (A2, Bw, Cg1, 2Cg2, and part of the 2Cg3 horizon)

The 10/2010 revision reflects a reclassification from Dystroxerepts to Humixerepts great group based on revisions to the 11th Edition Keys to Soil Taxonomy. This series should be investigated further to determine depth to aquic conditions and proper subgroup placement (Aquandic vs. Vitrandic).

National Cooperative Soil Survey
U.S.A.