LOCATION SEDDOW                  ID

Established Series
Rev. TWH/BDG/EMM
10/2013

SEDDOW SERIES

The Seddow series consists of deep well drained soils on hills on basalt plateaus and structural benches in canyons. They formed in mixed volcanic ash and loess over material weathered from basalt. Slope ranges from 3 to 50 percent. The average annual temperature is about 42 degrees F and the average annual precipitation is about 27 inches.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Vitrandic Haploxeralfs

TYPICAL PEDON: Seddow ashy silt loam on a 10 percent west-facing slope at 4,650 feet elevation in coniferous forest. When described on July 31, 1991 the soil was moist throughout. (Colors are for dry soil unless otherwise stated).

Oi--0 to 1 inch; moss, needles, and twigs (0 to 2 inches thick)

A--1 to 5 inches; brown (10YR 4/3) ashy silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many fine and very fine roots; many fine and very fine irregular and tubular pores; less than 3 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (2 to 7 inches thick)

E/B--5 to 9 inches; yellowish brown (10YR 5/4) ashy silt loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and medium and few coarse roots; common fine and very fine tubular pores; less than 5 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (5 to 8 inches thick)

B/E--9 to 14 inches; light yellowish brown (10YR 6/4) silt loam, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common fine and medium and few coarse roots; common fine and very fine tubular pores; 5 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (0 to 10 inches thick)

Bt1--14 to 22 inches; light yellowish brown (10YR 6/4) silty clay loam, dark yellowish brown (10YR 3/4) moist, dark yellowish brown (10YR 4/4) crushed, moist; moderate medium and coarse subangular blocky structure parting to strong fine angular blocky; hard, friable, moderately sticky and moderately plastic; common fine and medium and few coarse roots; few fine and very fine tubular pores; few faint discontinuous dark yellowish brown (10YR 4/4) clay films on faces of peds; many prominent discontinuous pale brown (10YR 6/3) skeletans on faces of peds; 5 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (6 to 47 inches thick)

2Bt2--22 to 30 inches; dark yellowish brown (10YR 4/4), yellowish brown (10YR 5/6) crushed, gravelly clay loam, dark yellowish brown (10YR 3/4) moist, dark yellowish brown (10YR 4/4) crushed, moist; moderate medium subangular blocky structure parting to strong fine angular blocky; hard, firm, moderately sticky and moderately plastic; few fine and medium roots; few fine tubular pores; many distinct continuous dark yellowish brown (10YR 4/4) clay films on faces of peds; few prominent patchy pale brown (10YR 6/3) skeletans on faces of peds; 20 percent gravel, 10 percent cobbles; moderately acid (pH 5.8); clear wavy boundary. (0 to 10 inches thick)

2Bt3--30 to 49 inches; dark yellowish brown (10YR 4/4), yellowish brown (10YR 5/6) crushed, extremely cobbly clay loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine roots matted around rock fragments; common prominent discontinuous dark yellowish brown (10YR 4/4) clay films on faces of peds; 30 percent gravel, 40 percent cobbles; moderately acid (pH 5.8); clear wavy boundary. (6 to 22 inches thick)

2R--49 inches; fractured basalt.

TYPE LOCATION: Nez Perce County, Idaho; about 1/4 mile east of Soldiers Meadow dam, about 550 feet north and 1,550 feet west of the southeast corner of section 29, T. 33 N., R. 3 W. Latitude - 46 degrees, 10 minutes, 01 seconds north; Longitude - 116 degrees, 43 minutes, 43 seconds west. USGS Winchester west Quadrangle.

RANGE IN CHARACTERISTICS:
Depth to argillic horizon - 4 to 20 inches
Depth to skeletal material - 23 to 47 inches
Depth to bedrock - 40 to 60 inches, (may be soft or hard)
Average annual soil temperature - 41 to 46 degrees F (Frigid temperature regime)
Soil moisture control section - dry throughout for 45 to 60 days in the period from June to September (Xeric moisture regime)
Particle-size control section (weighted averages:
Clay content - 24 to 35 percent
Coarse fragment content - 10 to 35 percent
Vitrandic feature - Volcanic glass content - 5 to 20 percent
Acid oxalate Al plus 1/2 Fe - 0.4 to 1.0 percent
Moist bulk density - 1.0 to 1.2 grams/cubic centimeter (estimated)
Phosphate retention - 25 to 55 percent (estimated)
Thickness - 7 to 11 inches (starting at mineral soil surface)

A horizon
Hue - 5YR to 10YR dry or moist
Value - 3 to 6 dry, 2 to 4 moist
Chroma - 2 to 6 dry and 1 to 6 moist
Texture - ashy loam or ashy silt loam
Clay content - 10 to 24 percent
Rock fragments - 0 to 15 percent gravel
Reaction - slightly acid or neutral

Bw horizon (when present)
Hue - 5YR to 10YR dry or moist
Value - 5 or 6 dry and 3 or 4 moist
Chroma - 3 to 6 dry or moist
Texture - ashy silt loam
Clay content - 15 to 24 percent
Rock fragments - 0 to 10 percent gravel
Reaction - moderately acid or slightly acid

E/B and B/E horizons (absent in some profiles)
Hue - 5YR to 10YR dry or moist
Value - 4 to 7 dry, 3 to 5 moist
Chroma - 3 or 4 dry or moist
Texture - ashy silt loam or ashy loam in the upper part, silt loam or loam in the lower part
Rock fragments - 0 to 20 percent gravel
Clay content - 14 to 24 percent
Reaction - moderately acid or slightly acid

Bt horizon
Hue - 5YR to 10YR dry or moist
Value - 4 to 6 dry, 3 to 5 moist
Chroma - 2 to 6 dry or moist
Textures - silty clay loam, clay loam, silt loam, or loam
Base saturation - 50 to 75 percent
Gravel content - 0 to 35 percent
Cobble content - 0 to 5 percent
Total rock fragment content - 0 to 35 percent
Clay content - 14 to 38 percent
Reaction - moderately acid to neutral

2Bt horizon
Hue - 5YR to 10YR dry or moist
Value - 4 or 5 dry, 3 to 5 moist
Chroma - 3 to 6 dry or moist
Textures - clay loam, silty clay loam, silt loam, or loam
Rock fragment content - 5 to 75 percent gravel, 0 to 40 percent cobbles, 5 to 75 percent total fragments
Clay content - 24 to 40 percent
Reaction - moderately acid or slightly acid

2BCt horizon (when present)
Value - 3 or 4 dry, 2.5 or 3 moist
Chroma - 2 to 4 dry or moist
Texture - clay loam or loam
Clay content - 24 to 30 percent
Gravel content - 10 to 25 percent
Cobble content - 5 to 40 percent
Total rock fragment content - 35 to 60 percent
Reaction - strongly acid or moderately acid

COMPETING SERIES:
Arson - deep to a paralithic contact
Kakyaticham - moderately deep to a lithic contact

GEOGRAPHIC SETTING: Seddow soils are on hills on basalt plateaus and structural benches in canyons. Slopes range from 3 to 50 percent. These soils formed in mixed volcanic ash and loess over material weathered from basalt. Elevations are 1,100 to 5,300 feet. Average annual precipitation is 25 to 45 inches, average annual temperature is 40 to 45 degrees F., and the frost free period is 80 to 125 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cramont, Culdesac, and Zaza series. Cramont soils have less than 10 percent coarse fragments in the particle-size control section, and are on ridgetops. Culdesac soils have a horizon of andic material greater than 14 inches thick, and are on north and east-facing hill sides. Zaza soils are shallow and are on convex hill sides.

DRAINAGE AND PERMEABILITY: Well drained; moderate to rapid runoff; saturated hydraulic conductivity is moderately high.

USE AND VEGETATION: These soils are used for timber production and livestock grazing. Native vegetation is mainly grand fir, Douglas-fir, ponderosa pine, longtube twinflower, and common snowberry.

DISTRIBUTION AND EXTENT: Northern Idaho; MLRAs 9 and 43A. This soil is of small extent.

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

SERIES ESTABLISHED: Nez Perce County, Idaho, 1995.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 5 inches (Oi and A horizons).
Vitrandic feature - The zone from 1 to 9 inches (A and E/B horizon).
Argillic horizon - The zone from 14 to 49 inches (Bt1, 2Bt2, and 2Bt3 horizons).
Particle-size control section - The zone from 14 to 34 inches (Bt1, 2Bt2, and part of the 2Bt3 horizon).

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National Cooperative Soil Survey
U.S.A.