LOCATION WAKANSAPA               NV

Established Series
Rev. BKP/JWM/PWB/JBF
07/2016

WAKANSAPA SERIES

Wakansapa series consists of shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks on mountain backslopes. Slopes are 8 to 30 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, mesic Aridic Lithic Argiustolls

TYPICAL PEDON: Wakansapa very gravelly ashy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered by approximately 40 percent gravel, and 15 percent cobbles.

Oi--0 to 2 cm; slightly decomposed twigs, needles, and leaves; neutral (pH 7.0); abrupt wavy boundary. (0 to 4 cm thick)

A--2 to 5 cm; dark grayish brown (10YR 4/2) very gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, and medium roots; common very fine and few fine dendritic tubular pores; 45 percent gravel, 10 percent cobbles; noneffervescent; neutral (pH 6.8); clear wavy boundary. (2 to 10 cm thick)

Bt1--5 to 20 cm; dark grayish brown (10YR 4/2) very gravelly ashy clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine, fine and medium roots; common very fine and few dendritic tubular pores; 40 percent gravel and 10 percent cobbles; noneffervescent; neutral (pH 7.1); clear wavy boundary.

Bt2--20 to 36 cm; brown (10YR 5/3) very gravelly ashy clay loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine, and few medium and coarse roots; common very fine and fine dendritic tubular pores; 45 percent gravel and 10 percent cobbles; noneffervescent; neutral (pH 7.0); very abrupt wavy boundary. (Combined thickness of the Bt horizons 28 to 45 cm thick)

R--36 cm; welded tuff.

TYPE LOCATION: Lincoln County, Nevada; about 17 meters South and 415 meters East from the Northwest corner of section 31, T. 5 S., R. 71 E.; USGS Docs Pass 7.5 minute topographic quadrangle; latitude 37 degrees 28 minutes 37.2 seconds N and longitude 114 degrees 6 minutes 8.1 seconds W; WGS84 Decimal Degrees 37.4770000 latitude, -114.1022500 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry; moist in winter and spring and in some part for 10 to 20 days cumulative from July through September due to summer convection storms; ustic soil moisture regime that borders on aridic.
Mean annual soil temperature: 8 to 12 degrees C.
Mollic epipedon thickness: 36 to 50 cm; includes the Bt1 horizon.
Depth to bedrock: 36 to 50 cm.
Reaction: Slightly alkaline or neutral.

Particle-size control section - Clay content: Averages 27 to 35 percent.
Rock fragments: 35 to 60 percent mainly gravel.

A horizon
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Mineralogy: 20 to 35 percent volcanic glass in the parent material and averages 0.01 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.

Bt horizons
Hue: 7.5YR or 10YR.
Value: 3 through 5 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Clay content: averages 27 to 35 percent with some pedons containing thin sub-horizons directly above the lithic contact that contain up to 45 percent clay.
Rock fragments: 35 to 60 percent.
Texture: Ashy sandy clay loam or ashy clay loam.
Mineralogy: 30 to 50 percent volcanic glass in the parent material and averages 0.1 to 0.2 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Structure: Moderate or strong, medium or coarse, subangular blocky or angular blocky structure.

COMPETING SERIES: These are no competing series.

GEOGRAPHIC SETTING: Wakansapa soils are on mountain backslopes. These soils formed in residuum and colluvium derived from welded tuff. Slopes are 8 to 30 percent. Elevations range from 1500 to 2300 meters. The mean annual precipitation is 300 to 350 mm, the mean annual air temperature is 7 to 11 degrees C, and the frost-free period is 100 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Acti, Cedaran, and Turba series. Acti and Cedaran soils average greater than 35 percent clay in the control section. Turba soils have a mollic epipedon thickness of 18 to 36 cm and are commonly located on upper mountain backslopes adjacent to rock outcrop.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high surface runoff; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Wakansapa soils are used for recreation, livestock grazing, and wildlife habitat. The potential native vegetation includes Mountain big sagebrush, Utah serviceberry, Gambels oak, and muttongrass with a minor component of singleleaf pinyon and Utah juniper. This pedon is correlated to ecological site R029XY164NV, Gravelly Clay Slope 12 to 16 P.Z.

DISTRIBUTION AND EXTENT: Southeastern Nevada. These soils are not extensive. MLRA 29.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Lincoln County, Nevada, 2009.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 2 to 36 cm (A, Bt1 and Bt2 horizons).
Argillic horizon - The zone from 5 to 36 cm (Bt1 and Bt2 horizons).
Vitrandic feature - The zone from 2 to 36 cm (A, Bt1, and Bt2 horizons).
Lithic contact - The boundary at 36 cm (R layer).
Particle-size control section - The zone from 5 to 36 cm (Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.