LOCATION TOKOPER                 NV

Established Series
Rev. JBF/RLB
07/2016

TOKOPER SERIES

The Tokoper series consists of shallow and very shallow over an indurated duripan, well drained soils that formed in residuum and colluvium derived from tuff, rhyolite and basalt. The Tokoper soils are on summits and shoulders of mesas, plateaus, mountains, hills and lava flows. Slopes are 2 to 50 percent. The mean annual precipitation is about 150 mm and the mean annual temperature is about 13 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic, shallow Typic Argidurids

TYPICAL PEDON: Tokoper very cobbly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 60 percent gravel, 20 percent cobbles, and 5 percent stones.

A--0 to 8 cm; light brownish gray (10YR 6/2) very cobbly sandy loam, grayish brown (10YR 5/2) moist; weak very thin and thin platy structure; soft, very friable, slightly sticky and nonplastic; few very fine roots, many fine and medium vesicular pores; 25 percent gravel, 15 percent cobbles and 5 percent stones; violently effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (5 to 13 cm thick)

Bt1--8 to 23 cm; light brown (7.5YR 6/4) very gravelly clay loam, brown (7.5YR 5/4) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and few medium roots; common very fine tubular pores; many faint clay films on faces of peds and in pores; 40 percent gravel and 10 percent cobbles; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (8 to 18 cm thick)

Bt2--23 to 36 cm; light brown (7.5YR 6/4) extremely gravelly loam, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; common very fine interstitial pores; common faint clay films on faces of peds; 50 percent gravel and 20 percent cobbles; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (5 to 15 cm thick)

Bqkm--36 to 38 cm; very pale brown (10YR 8/2) continuous indurated silica and carbonate laminar cap; abrupt wavy boundary (2 mm to 2.5 cm thick)

R--38 cm; unweathered welded tuff.

TYPE LOCATION: Nye County, Nevada; 1/2 mile west of Stonewall Pass and about 900 feet north and 500 feet east of the projected southwest corner of section 33. T. 6 S., R. 43 E.; USGS Scottys Junction SW 7.5 minute topographic quadrangle; latitude 37 degrees 22 minutes 10 seconds N and longitude 117 degrees 9 minutes 55 seconds W; WGS84 Decimal Degrees 37.3694444 latitude, -117.1652778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in some part for short periods during the winter and early spring months and for 10 to 20 days cumulatively in July to October following convection storms; typic aridic soil moisture regime.
Mean annual soil temperature: 12 to 14 degrees C.
Depth to duripan: 20 to 36 cm.
Depth to bedrock: 23 to 38 cm.
Carbonates: Slightly effervescent through violently effervescent.

Particle-size control section - Clay content: Averages 18 to 27 percent.
Rock fragments: Averages 40 to 60 percent, mainly volcanic gravel; 5 to 15 percent cobbles.

A horizon
Hue: 7.5YR or 10YR.
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 or 3, dry or moist.

Bt horizon
Value: 5 or 6 dry, 3 to 5 moist.
Chroma: 2 through 4 dry or moist.
Texture: Sandy clay loam, loam or clay loam in upper part; loam or sandy loam in lower part.
Rock fragments: 35 to 55 percent in upper part, 50 to 75 percent in lower part. Average 40 to 60 percent.
Consistence: Soft or slightly hard, slightly sticky or sticky and slightly plastic or plastic.
Reaction: Moderately alkaline or strongly alkaline.

COMPETING SERIES: These are the Lyda, Maggie, Silverbow, Stingdorn and Tomel series.

The Lyda, Maggie, Silverbow, Stingdorn and Tomel soils all lack bedrock within a depth of 36 cm. The Stingdorn series lack appreciable summer precipitation and have argillic horizons with hue of 10YR or 2.5Y.

GEOGRAPHIC SETTING: Tokoper soils are on summits and shoulders of mesas, plateaus mountains, hills and lava flows. These soils formed in residuum and colluvium derived from various volcanic rocks. Slopes are 2 to 50 percent. Elevations are 1,220 to 2,200 meters. The climate is cool, semiarid with cool moist winters, and hot, dry summers with occasional rain storms. The mean annual precipitation is 125 to 200 mm, mean annual temperature is 11 to 13 degrees C, and the frost-free season is about 120 to 200 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Downeyville and Blacktop soils. Downeyville soils lack a continuous laminar cap on bedrock. The Blacktop soils lack an argillic horizon.

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

USE AND VEGETATION: Livestock grazing and wildlife habitat. The present vegetation is mainly shadscale, spiny hopsage, spiny menodora, ephedra, and galleta.

DISTRIBUTION AND EXTENT: Southern Nevada. These soils are moderately extensive. MLRA 29.

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

SERIES ESTABLISHED: Esmeralda County, Nevada, (Southwest Part) 1984.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 8 cm (A horizon).
Argillic horizon - The zone from 8 to 36 cm (Bt1 and Bt2 horizons).
Duripan - The layer at 36 to 38 cm (Bqkm horizon).
Lithic contact - The boundary at 38 cm (R layer).
Particle-size control section - The zone from the surface to 36 cm (A, Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.