LOCATION OKAN                    NV

Established Series
Rev. LJL-RLB-JVC-JBF
11/2016

OKAN SERIES

Okan series consists of very deep, well drained soils that formed in alluvium derived from mixed rocks, loess, and volcanic ash. Okan soils are on inset fans, fan skirts, and barrier beaches. Slopes are 0 to 8 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, calcareous, mesic Duric Torriorthents

TYPICAL PEDON: Okan sandy loam--rangeland. The soil surface is covered with approximately 15 percent gravel. (Colors are for dry soil unless otherwise noted.)

A1--0 to 8 cm; brown (10YR 5/3) sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium platy structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and few fine roots; many very fine interstitial pores; 5 percent gravel; many fine and few medium carbonate coats on various sides of rock fragments; slightly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (5 to 10 cm thick)

A2--8 to 20 cm; light gray (10YR 7/2) sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine fine, common medium and few coarse roots; many very fine interstitial pores; 5 percent gravel; many fine and few medium carbonate coats on various sides of rock fragments; slightly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (10 to 15 cm thick)

Bqk1--20 to 46 cm; very pale brown (10YR 7/3) sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine and fine, common medium and coarse roots; many very fine interstitial and common very fine tubular pores; 5 percent durinodes 1.2 cm in diameter; 10 percent gravel; many fine and few carbonate coats on various sides of rock fragments; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (20 to 30 cm thick)

Bqk2--46 to 97 cm; light gray (10YR 7/2) cobbly sandy loam, brown (10YR 5/3) moist; massive; soft, very friable, slightly sticky and nonplastic; common very fine and fine, few medium and coarse roots; many very fine interstitial pores; 30 percent durinodes 2.5 cm in diameter; 5 percent gravel and 10 percent cobbles; many fine and few medium carbonate coats on various sides of rock fragments; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (40 to 60 cm thick)

2Ck--97 to 152 cm; light gray (10YR 7/2) stratified extremely gravelly loamy sand to loamy sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine, few medium and coarse roots; many very fine interstitial pores; 55 percent gravel and 10 percent cobbles; many fine coats of carbonate coats on various sides of rock fragments; strongly effervescent; strongly alkaline (pH 8.6).

TYPE LOCATION: Elko County, Nevada; about 6 miles southeast of Currie; in a nonsectionized township approximately 900 feet east and 1.6 miles north of the northwest corner of section 4, T. 26 N., R. 65 E.; USGS Goshute Lake North 7.5 minute topographic quadrangle; latitude 40 degrees 11 minutes 14 seconds N and longitude 114 degrees 39 minutes 12 seconds W; WGS84 Decimal Degrees 40.1871944 latitude, -114.6533333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in late fall and early spring, dry late spring through mid fall; aridic (torric) soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 11 degrees C.
Depth to horizons with durinodes: 36 to 56 cm.
Depth to stratified horizons with sandy or sandy-skeletal materials: 89 to 100 cm.
Other features: The carbonate coats on various sides of the rock fragments is nonpedogenic.

Particle-size control section - Clay content: Averages 8 to 18 percent.
Rock fragments: Averages 0 to 20 percent, mainly gravel.

A horizons
Value 5 through 7 dry, 3 or 4 moist. The upper 18 cm when mixed has value of 6 or 7 dry and 4 moist.
Chroma: 2 or 3, dry or moist.
Calcium carbonate equivalent: 1 to 5 percent.

Bqk1 horizon
Value: 6 or 7 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Secondary silica: 5 to 10 percent durinodes.
Calcium carbonate equivalent: 5 to 10 percent.

Bqk2 horizon
Clay content: 8 to 18 percent.
Secondary silica: 20 to 35 percent durinodes.
Calcium carbonate equivalent: 5 to 15 percent.

2Ck horizon
Texture: Stratified extremely gravelly loamy sand to loamy sand.
Clay content: 4 to 8 percent.
Calcium carbonate equivalent: 5 to 15 percent.

COMPETING SERIES: These are the Beryl, Blimo, Bubus, Coldent, Nyak, and Valmy series.

Beryl and Blimo, soils have horizons with a firm, brittle matrix within 100 cm of the soil surface. Bubus, Coldent, and Valmy soils have a typic aridic (torric) moisture regime. Linco soils average 20 to 35 percent rock fragments in the particle-size control section. Nyak soils do not have sandy or sandy-skeletal materials within 100 cm of the soil surface.

GEOGRAPHIC SETTING: Okan soils are on inset fans, fan skirts, and barrier beaches. These soils formed in alluvium derived from mixed rocks, loess, and volcanic ash. Slopes are 0 to 8 percent. Elevations range from 1,710 to 2,290 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 mm, the mean annual temperature is 7 to 9 degrees C, and the frost-free period is 100 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Eastwell and Shabliss soils. Eastwell soils are shallow to a strongly cemented duripan. Shabliss soils are shallow to an indurated duripan.

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

USE AND VEGETATION: Okan soils are used for rangeland and wildlife habitat. The present vegetation is mainly Wyoming big sagebrush, spiny hopsage, and Indian ricegrass.

DISTRIBUTION AND EXTENT: Eastern Nevada. These soils are moderately extensive. MLRA 28B.

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

SERIES ESTABLISHED: Elko County, Nevada, Southeast Part, 1994.

REMARKS: Future study of this series is needed to determine whether it would be more properly classified in the Aridisol order as a Durinodic Xeric Haplocambid.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1 and part of the A2 horizons).
Duric feature - The zone from 46 to 97 (Bqk2 horizon).
Particle-size control section - The zone from 25 to 100 cm (Bqk2 horizon and parts of the Bqk1 and 2Ck horizons).

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National Cooperative Soil Survey
U.S.A.