LOCATION FITZWIL IDEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy Vitrandic Palecryalfs
TYPICAL PEDON: Fitzwil gravelly ashy silt loam, supporting a subalpine fir/pinegrass habitat type, pinegrass phase, woodland; on a 14 percent slope with a south aspect; about 7200 feet elevation. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; forest litter of needles, twigs and stems; abrupt smooth boundary. (0 to 2 inches thick)
A1--1 to 8 inches; dark grayish brown (10YR 4/2) gravelly ashy silt loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; soft very friable, slightly sticky and slightly plastic; many very fine, few fine, medium and coarse roots; many very fine irregular pores; 15 percent pebbles; slightly acid (pH 6.4); abrupt smooth boundary. (3 to 10 inches thick)
A2--8 to 15 inches; brown (10YR 5/3) gravelly ashy loam, dark brown (10YR 3/3) moist; weak coarse subangular blocky structure parting to weak fine granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, few fine, medium and coarse roots; many very fine irregular pores; 20 percent pebbles, trace cobbles and stones; slightly acid (pH 6.2); clear smooth boundary. (0 to 10 inches thick)
E--15 to 28 inches; pale brown (10YR 6/3) very gravelly ashy loam, brown (10YR 4/3) moist; weak coarse subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; common very fine tubular pores; few faint streaks and stains of B material and few fine (less than 1/4 inch) distinct lamellae; 40 percent pebbles, 5 percent cobbles, trace stones; slightly acid (pH 6.2); clear irregular boundary. (5 to 25 inches thick)
E/Bt--28 to 37 inches; 60 percent very pale brown (10YR 7/3) E material, brown (10YR 5/3) moist, 40 percent light yellowish brown (10YR 6/4) B material, yellowish brown (10YR 5/4) moist in a fine to medium irregular matrix that mixes to extremely gravelly ashy loam; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine tubular pores; common distinct clay films on fed faces, on rock faces and lining pores; 45 percent pebbles, 15 percent cobbles, trace stones; moderately acid (pH 5.6); gradual wavy boundary. (5 to 15 inches thick)
Bt/E1--37 to 51 inches; 50 percent light yellowish brown (10YR 6/4) B material, yellowish brown (10YR 5/4) moist and 50 percent very pale brown (10YR 8/2) E material, light brownish gray (10YR 6/2) moist in a fine to medium (less than 1/2 inch) irregular matrix that mixes to extremely cobbly ashy loam; weak medium subangular blocky structure parting to weak very fine subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and common fine tubular pores; common distinct clay films on ped faces, on rock fragments and lining pores; 15 percent pebbles, 40 percent cobbles, 5 percent stones; moderately acid (pH 5.8); clear smooth boundary. (10 to 20 inches thick)
Bt/E2--51 to 60 inches; 50 percent light yellowish brown (10YR 6/4) B material, dark yellowish brown (10YR 4/4) moist and 50 percent very pale brown (10YR 8/2) E material, light brownish gray (10YR 6/2) moist in a fine to medium (less than 1/4 inch) irregular matrix that mixes to extremely cobbly ashy loam; weak coarse subangular blocky structure parting to moderate very fine subangular blocky (B material) and weak very fine subangular blocky (E material); slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine and few fine tubular pores; few distinct clay films on ped faces, on rock fragments and lining pores; 20 percent pebbles, 35 percent cobbles, 10 percent stones; moderately acid (pH 5.6).
TYPE LOCATION: Clark County, Idaho; about 30 miles north and 9 miles west of Ashton, Idaho; about 2300 feet south and 1200 feet west of the northeast corner of sec. 28, T.14 N., R.41 E. Latitude: 44 degrees North, 30 minutes, 41 seconds. Longitude: 111 degrees West, 37 minutes, 23 seconds.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 36 to 40 degrees F.
Mean summer soil temperature - 41 to 45 degrees F. with an O horizon, 48 to 52 degrees F. without an O horizon
Moisture control section - between 4 and 12 inches.
The soil is dry throughout the moisture control section for 30 to 45 consecutive days during the four months following the summer solstice.
Umbric epipedon thickness - 10 to 20 inches
Depth to argillic horizon - 24 to 40 inches
Ammonium oxalate extractable Al plus 1/2 Fe - 0.1 to 1.0 percent
Phosphate retention - 20 to 50 percent
A1 horizon - Hue: 10YR or 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Texture: ashy silt loam
Clay content: 7 to 18 percent
Rock fragment content: 0 to 30 percent
Pebbles: 0 to 30 percent
Cobbles: 0 to 5 percent
Base saturation by ammonium acetate: 30 to 50 percent
Reaction: strongly acid to slightly acid (pH 5.1 to 6.5)
Volcanic glass content: 5 to 30 percent in the 0.02 to 2.0 mm size fraction
Ammonium oxalate extractable Al plus 1/2 Fe - 0.1 to 0.4 percent
A2 horizon - Hue: 10YR or 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Texture: ashy silt loam or ashy loam
Clay content: 7 to 18 percent
Rock fragment content: 15 to 55 percent
Pebbles: 15 to 50 percent
Cobbles: 0 to 5 percent
Reaction: strongly acid to slightly acid (pH 5.1 to 6.5)
Volcanic glass content: 5 to 30 percent in the 0.02 to 2.0 mm size fraction
Ammonium oxalate extractable Al plus 1/2 Fe - 0.1 to 0.4 percent
E or E/B (when present) horizon - Hue: 10YR or 7.5YR
Value: E part 6 or 7 dry, 4 or 5 moist
B part 5 or 6 dry, 4 or 5 moist
Chroma: E part 2 or 3 dry or moist
B part 3 or 4 dry or moist
Texture: ashy loam or ashy silt loam
Clay content: 7 to 18 percent
Rock fragment content: 15 to 60 percent
Pebbles: 15 to 55 percent
Cobbles: 0 to 10 percent
Stones: 0 to 5 percent
Base saturation by ammonium acetate: 50 to 80 percent
Reaction: strongly acid to slightly acid (pH 5.1 to 6.5)
Volcanic glass content: 5 to 30 percent in the 0.02 to 2.0 mm size fraction
Ammonium oxalate extractable Al plus 1/2 Fe - 0.4 to 1.0 percentOther: 85 to 100 percent E material, 0 to 15 percent B material by volume
E/Bt horizon - Hue: 10YR or 7.5YR
Value: E part 6, 7 or 8 dry, 5 or 6 moist
B part 5 or 6 dry, 4 or 5 moist
Chroma: E part 2 or 3 dry or moist
B part 3 or 4 dry, 3, 4, or 6 moist
Texture: ashy loam, ashy silt loam or ashy sandy loam
Clay content: 12 to 18 percent
Rock fragment content: 35 to 80 percent
Pebbles: 15 to 70 percent
Cobbles: 0 to 35 percent
Stones: 0 to 10 percent
Base saturation by ammonium acetate: 60 to 100 percent
Reaction: strongly acid to slightly acid (pH 5.1 to 6.5)
Volcanic glass content: 15 to 60 percent in the 0.02 to 2.0 mm size fraction
Ammonium oxalate extractable Al plus 1/2 Fe - 0.4 to 1.0 percent
Other: 50 to 85 percent E material, 15 to 50 percent B material by volume
Bt/E horizons - Hue: 7.5YR or 10YR
Value: B part - 5 or 6 dry, 4 or 5 moist
E part - 6 to 8 dry, 5 or 6 moist
Chroma: B part - 3 or 4 dry, 3, 4, or 6 moist
E part - 2 or 3 dry or moist
Texture: ashy loam, ashy silt loam or ashy sandy clay loam
Rock fragment content: 35 to 80 percent
Pebbles: 15 to 55 percent
Cobbles: 5 to 40 percent
Stones: 0 to 15 percent
Base saturation by ammonium acetate: 60 to 100 percent
Reaction: moderately acid or slightly acid (pH 5.6 to 6.5)
Volcanic glass content: 5 to 60 percent in the 0.02 to 2.0 mm size fraction
Ammonium oxalate extractable Al plus 1/2 Fe - 0.1 to 1.0 percent
Other: 50 to 85 percent B material, 15 to 50 percent E material by volume
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Fitzwil soils are on foothill and mountain summits and plateaus. Slopes range from 4 to 25 percent. Elevations range from 6,500 to 9,400 feet. The soil formed in local alluvium or colluvium derived from loess, volcanic ash and rhyolitic tuff or mixed alluvium. The average annual precipitation is about 25 to 30 inches. It falls dominantly in late autumn through early summer. Winter snowpack of greater than 5 feet in depth and lasting through May are common. Average air temperature is about 34 to 38 degrees F. The frost-free season is 15 to 50 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the tentative Koffgo and Rhylow series. Koffgo soils occur intermixed with the Fitzwil soils on all landforms represented. They occupy cooler, more moist positions. They lack umbric epipedons and argillic horizons. Rhylow soils occur on adjacent mountain and foothill sideslopes. They lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow to moderate runoff; moderate permeability.
USE AND VEGETATION: Fitzwil soils are used for recreation, woodland, wildlife habitat and livestock grazing. These soils dominantly support Douglas-fir/elksedge, Douglas-fir/pinegrass and mountain big sagebrush/Idaho fescue communities. The potential native vegetation are plant associations in the subalpine fir and whitebark pine series.
DISTRIBUTION AND EXTENT: Southeastern Idaho. The soil is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Targhee National Forest, Clark County, Idaho, 1997.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - the zone from 1 to 15 inches (A1 and A2 horizons).
Argillic horizon - the zone from 37 to 60 inches (Bt/E1 and Bt/E2 horizons).
Particle-size control section - the zone from 37 to 57 inches (Bt/E1 and portion of the Bt/E2 horizons).
Ashy class - The zone from 15 to 60 inches (E and E/Bt horizons)
Andic soil properties - The zone from 15 to 60 inches (E, E/Bt, and Bt/E horizons)
Vitrandic subgroup feature - the zone from the mineral soil surface to 60 inches (A1, A2, E, E/Bt, Bt/E1, Bt/E2 horizons)
Moisture regime - udic.
Additional Data: Full characterization data (8/26/96), NSSL, Lincoln, NE. Client assigned lab number: S94ID-033-001; project file
number 95P27; pedon 95P-155; sample 95P, 1054-1059.