LOCATION ERAKATAK                OR+NV

Established Series
Rev. ARW-TM-JVC-JBF
01/2019

ERAKATAK SERIES

The Erakatak series consists of moderately deep, well drained soils that formed in residuum and colluvium derived from volcanic rocks with surface mantles of volcanic ash. Erakatak soils are on plateaus, hills, and mountains. Slopes are 2 to 80 percent. The mean annual precipitation is about 400 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Vitrandic Argixerolls

TYPICAL PEDON: Erakatak very cobbly ashy loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 5 cm; grayish brown (10YR 5/2) very cobbly ashy loam, dark brown (10YR 3/3) moist; moderate medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; common very fine, common fine, and few medium interstitial pores; 20 percent gravel, 15 percent cobbles, and 5 percent stones; neutral (pH 6.6); clear smooth boundary. (5 to 13 cm thick)

A2--5 to 18 cm; brown (10YR 5/3) very cobbly ashy loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure parting to moderate medium granular; slightly hard, friable, slightly sticky and slightly plastic; common very fine, common fine, and common medium roots; common very fine, common fine, and few medium interstitial pores; 15 percent gravel, 15 percent cobbles, and 5 percent stones; neutral (pH 6.8); abrupt smooth boundary. (10 to 20 cm thick)

Bt1--18 to 41 cm; brown (10YR 5/3) very cobbly ashy clay loam, dark brown (10YR 3/3) moist; strong medium angular blocky structure parting to moderate fine angular blocky; hard, firm, moderately sticky and moderately plastic; few very fine, common fine, common medium, and few coarse roots; few very fine, common fine, and few medium tubular pores; common distinct clay films on faces of peds; 20 percent gravel, 15 percent cobbles, and 5 percent stones; neutral (pH 7.0); clear wavy boundary. (13 to 38 cm thick)

Bt2--41 to 64 cm; light yellowish brown (10YR 6/4) very cobbly clay, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure parting to moderate medium angular blocky; very hard, very firm, very sticky and very plastic; few very fine through coarse roots; few fine, few medium, and few coarse tubular pores; common prominent clay films on faces of peds; 25 percent gravel and 20 percent cobbles; neutral (pH 7.2); clear smooth boundary. (18 to 56 cm thick)

R--64 cm; fractured welded tuff.

TYPE LOCATION: Harney County, Oregon; about 0.5 miles north of Emigrant Creek; approximately 1,900 feet north and 1,000 feet east of the southwest corner of section 20, T. 20 S., R. 29 E.; USGS Hughet Valley 7.5 minute topographic quadrangle; latitude 43 degrees 49 minutes 20 seconds N and longitude 119 degrees 16 minutes 23 seconds W; WGS84 Decimal Degrees 43.8218680 latitude, -119.2732830 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section in winter and spring, dry late July through late October; xeric soil moisture regime that borders on aridic.
Mean annual soil temperature: 5 to 8 degrees C.
Mollic epipedon thickness: 20 to 48 cm; includes the Bt1 horizon in some pedons.
Depth to bedrock: 50 to 100 cm to a lithic contact.
Vitrandic intergrade properties: Occurs in horizons from the soil surface to at least 18 cm in depth within horizons having clay content of less than about 40 percent.

Particle-size control section - Clay content: Averages 35 to 55 percent.
Rock fragments: 35 to 60 percent, mainly cobbles. Lithology of fragments are volcanic rocks such as tuff or basalt.

A horizons
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 through 3, dry or moist.
Organic matter content: 1 to 5 percent.
Volcanic glass content: 5 to 30 percent in coarse silt through fine sand fractions.
Oxalate Al + 1/2 oxalate iron: 0.2 to 0.4 percent.

Bt1 horizon
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 through 4, dry or moist.
Texture: Very cobbly ashy clay loam, very cobbly ashy silty clay loam, or very cobbly clay.
Clay content: 30 to 50 percent.
Consistence: Moderately sticky or very sticky and moderately plastic or very plastic, wet.
Organic matter content: 1 or 2 percent.
Reaction: Neutral or slightly alkaline.
Volcanic glass content: 5 to 30 percent in coarse silt through fine sand fractions in the Bt1 horizon.
Oxalate Al + 1/2 oxalate iron: 0.2 to 0.4 percent.

Bt2 horizon
Hue: 10YR or 7.5YR.
Value: 4 through 6 dry, 2 through 4 moist with darker value in the upper subhorizon.
Chroma: 2 through 4, dry or moist.
Texture: Very cobbly clay or very gravelly clay.
Clay content: 40 to 60 percent.
Reaction: Neutral or slightly alkaline.
Other features: Some pedons have pressure cutans in at least one of the Bt horizons; some pedons have relict redox concentrations of iron in the Bt2 horizon; some pedons have coats of opaline silica.

COMPETING SERIES: These are the Breeseranch, Dupratt, Finsel, Hamtah, Homecamp, Humarel, Lamulita, Maule, Menbo, Potlid, Shotsprings, Squatterflat and Wiltop series.

Breeseranch, Hamtah, Lamulita, Squatterflat and Wiltop soils are deeper than 100 cm. Dupratt, Finsel and Menbo soils have mollic epipedons that are deeper than 50 cm thick. Humarel, Maule, Potlid and Shotsprings soils have an Oi horizon.

GEOGRAPHIC SETTING: Erakatak soils are on plateaus, hills, and mountains. They typically occur on summits or south-facing backslope positions. They formed in colluvium and residuum derived mainly from volcanic rocks with surface mantles of volcanic ash. Slopes are 2 to 80 percent. Elevations range from 1,310 to 2,595 meters. The climate is semiarid with cold, moist winters and warm, dry summers. The mean annual precipitation is 300 to 460 mm, the mean annual temperature is 4 to 7 degrees C, and the frost-free period is 50 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chen, Hackwood, and Tusel soils. Chen soils are shallow to lithic contacts. Hackwood soils are fine-loamy, very deep, have thick mollic epipedons, and do not have argillic horizons. Tusel soils are loamy-skeletal, have thick mollic epipedons, and are greater than 100 cm to bedrock.

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

USE AND VEGETATION: Erakatak soils are used for livestock grazing and wildlife habitat. The vegetation is mainly mountain big sagebrush, Wyoming big sagebrush, Idaho fescue, bluebunch wheatgrass, basin wildrye, snowberry, cheatgrass, mountain brome, mule's ear wyethia, lupine, bottlebrush squirreltail, onion, and a minor amount of antelope bitterbrush and Thurber's needlegrass.

DISTRIBUTION AND EXTENT: Northern Nevada and south-central Oregon. These soils are moderately extensive. The series concept and main acreage is in MLRA 23, while other acreage occurs in MLRAs 10, 25, and 43C.

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

SERIES ESTABLISHED: Northwest Elko County Area, Nevada, 1986.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 16 cm (A1, A2, and Bt1 horizons).
Argillic horizon - The zone from 7 to 25 cm (Bt1 and Bt2 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 41 cm (A1, A2, and Bt1 horizons).
Lithic contact - The boundary at 25 cm to underlying hard, unweathered bedrock (R layer).
Particle-size control section - The zone from 7 to 25 cm (Bt1 and Bt2 horizons).

The revision of July 2003 updated the taxonomic class from Clayey-skeletal, smectitic, frigid Typic Argixerolls, moved the type location to a more representative area, and clarified the concept of the bedrock contact.

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National Cooperative Soil Survey
U.S.A.