LOCATION SPOKANE WA+ID

Established Series
Rev. NCD/BDG/RJS
06/2016

SPOKANE SERIES

The Spokane series consists of moderately deep, well drained soils formed in colluvium and residuum weathered from granite, gneiss and schist mixed with loess and volcanic ash in the upper part. Spokane soils are on hills, mountains and ridgetops. Slopes are of 3 to 65 percent. The mean annual precipitation is about 550 mm, and the mean annual air temperature is about 8.9 degrees C.

TAXONOMIC CLASS: Coarse-loamy, isotic, mesic Vitrandic Haploxerolls

TYPICAL PEDON: Spokane ashy loam, woodland. (Colors are for dry soil unless otherwise noted)

Oi--0 to 3 cm; partially decomposed organic litter, composed of pine needles, leaves, twigs, and cones; strongly acid (pH 5.5); abrupt smooth boundary. (0 to 3 cm thick)

A1--3 to 10 cm; grayish brown (10YR 5/2) ashy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; many roots; many very fine interstitial pores; 5 percent gravel; slightly acid (pH 6.4); clear smooth boundary.

A2--10 to 25 cm; brown (10YR 5/3) ashy sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; many roots; many very fine tubular and irregular pores; 10 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (A1, A2 horizons combined thickness - 18 to 41 cm)

Bt--25 to 46 cm; pale brown (10YR 6/3) gravelly coarse sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common roots; many very fine tubular and irregular pores; few patchy faint clay films in pores and on mineral grains; 20 percent gravel; slightly acid (pH 6.3); clear wavy boundary. (0 to 50 cm thick)

BCt--46 to 66 cm; pale brown (10YR 6/3) gravelly coarse sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, friable, nonsticky and nonplastic; common roots; many very fine tubular and irregular pores; few irregular horizontal bands of dark yellowish brown (10YR 4/4) moist loam, 2 to 5 mm. thick, containing faint patchy clay films in pores; 20 percent gravel; slightly acid (pH 6.5); gradual irregular boundary. (0 to 38 cm thick)

Cr--66 cm; pale brown (10YR 6/3), light gray (10YR 7/2), and gray (10YR 5/1) weathered granite; crumbles to gravelly loamy coarse sand; few roots; neutral (pH 6.9).

TYPE LOCATION: Spokane County, Washington; About 1.5 miles northeast of Foothills, WA. and 200 feet (60 m) west and 1,870 feet (570 m)_north of the southeast corner of Section 1, Township 26 N, Range 44 E; USGS Foothills, WA. topographic quadrangle; (Latitude 47 degrees, 46 minutes, 40.4 seconds N. and Longitude 117 degrees, 10 minutes, 33.8 seconds W.) NAD 83.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature (at 50 cm) - 8.3 to 11.7 degrees C.
Soil moisture regime - dry 75 to 90 consecutive days following the summer solstice
Base saturation (sum of cations) - less than 75 percent in the upper 75 cm
Rock fragment content - 15 to 35 percent
Depth to a paralithic contact - 50 to 100 cm
Depth to a lithic contact - greater than 100 cm
Mollic epipedon thickness - 18 to 41 cm
Soil reaction - slightly acid to neutral
Volcanic ash influence - 18 to 41 cm
Estimated properties of ash influence layer:
Volcanic glass content - 5 to 20 percent,
Acid-oxalate extractable Al + Fe - 0.4 to 1.0 percent
15-bar water retention - 5 to 10 percent (air dried) samples

A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture ashy loam, ashy sandy loam
Rock fragments - 0 to 15 percent gravel, 0 to 5 percent cobbles, 0 to 15 percent stones

Bt horizon (or Bw horizon when present)
Value - 5 or 6 dry, 3 or 4 moist
Chroma 3 or 4 dry or moist
Texture - loam, sandy loam, coarse sandy loam
Rock fragments - 10 to 30 percent gravel, 0 to 10 percent cobbles (total 10 to 35 percent)

BCt horizon (or BC horizon when present)
Hue - 10YR or 2.5Y
Value - 5 to 7 dry, 4 or 5 moist
Chroma - 2 to 4 dry or moist
Texture - sandy loam, coarse sandy loam, loamy coarse sand
Rock fragments - 5 to 30 percent gravel, 0 to 5 percent cobbles

Note: C horizon may be present in some pedons.

COMPETING SERIES:
Donavan (WA) - have a densic contact at a depth of 50 to 100 cm
Fourmound (WA) - do not have a paralithic contact
Goldlake (WA) - have a densic contact at a depth of 100 to 150 cm
Monkeycreek (OR) - are very
Seaboldt (WA) - are moderately deep to a lithic contact
Usk (WA) - are dry for 60 to 75 consecutive days following the summer solstice.

GEOGRAPHIC SETTING:
Landforms - hills, mountains and ridgetops
Elevations - 450 to 1,220 meters
Slopes - 3 to 65 percent
Parent material - formed in colluvium and residuum weathered from granite, gneiss and schist mixed with loess and volcanic ash in the upper part
Climate - warm, relatively dry summers and cool, moist winters
Mean annual precipitation - 375 to 800 mm
Mean annual air temperature - 5.6 to 10.6 degrees C.
Frost-free season - 90 to 145 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Centralpeak, Donavan, Dragoon, Green Bluff, Mobate, Micapeak, Raisio, Skanid, and Tekoa soils. Centralpeak soils have an ochric epipedon, are frigid and are on side slopes of mountains. Donavan soils are more than 100 cm deep and are on side slopes of hills and mountains. Mobate and Skanid soils are 25 to 50 cm deep and are on mountains. Dragoon and Tekoa soils have an argillic horizon with more than 18 percent clay and are on mountains. Green Bluff soils have an ochric epipedon, are more than 100 cm deep and are on basalt plateaus. Micapeak soils are frigid, have an ochric epipedon and are on side slopes of mountains and foothills. Raisio soils are loamy-skeletal and are on south-facing side slopes of mountains.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well-drained; high saturated hydraulic conductivity.

USE AND VEGETATION: These soils are used for rural home sites, grazeable woodland, livestock grazing, timber production, wildlife habitat, and some dryland cropland. Native vegetation is ponderosa pine and scattered Douglas-fir, with an understory of common snowberry, snowbrush ceanothus, bluebunch wheatgrass, Idaho fescue, baldhip rose, and pinegrass. Native vegetation on dry sites is ponderosa pine with an understory of Idaho fescue and antelope bitterbrush.

DISTRIBUTION AND EXTENT: Northeastern Washington and northern Idaho; MLRA 43A. Series is moderately extensive.

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

SERIES ESTABLISHED: Spokane County, Washington; 1964.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 3 to 25 cm (A1, A2 horizons)
Vitrandic feature - the zone from 3 to 25 cm (A1, A2 horizons)
Cambic horizon - the zone from 25 to 66 cm with presence of oriented clay but less than a 20 percent increase in clay from the overlying horizon (Bt, BCt horizons)
Ultic feature - the zone from 3 to 66 cm inches having a base saturation (sum) of less than 75 percent (A1, A2, Bt, BCt horizons)
Paralithic contact - the zone beginning at 66 cm (Cr horizon).
Particle-size control section - the zone from 28 to 66 cm (part of Bt, BCt horizons).

ADDITIONAL DATA: Partial laboratory data available for Soil Survey Sample Numbers: 83WA019001 Ferry County, WA., NSSL Pedon Number: 84P0164, 96WA065001 Stevens County, WA., NSSL Pedon Number: 96P0073, 99WA0639005 Spokane County, WA. NSSL Pedon Number: 00P0798,

Spokane soils should be further investigated to determine typical mineralogy (isotic vs. mixed).

National Cooperative Soil Survey
U.S.A.