LOCATION COSER                   NV+ID

Established Series
Rev. DWW-RLB-JVC-JBF
01/2019

COSER SERIES

The Coser series consists of moderately deep, well drained soils that formed in colluvium over residuum derived from tuff and tuffaceous sedimentary rocks. Coser soils are on hills, mountains, pediments. Slopes are 4 to 50 percent. The mean annual precipitation is about 360 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine, smectitic, frigid Typic Palexerolls

TYPICAL PEDON: Coser gravelly clay loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 70 percent gravel.

A--0 to 10 cm; grayish brown (10YR 5/2) gravelly clay loam, very dark grayish brown (10YR 3/2) moist; weak thin platy structure; hard, friable, moderately sticky and moderately plastic; many very fine roots; many very fine and fine, few medium vesicular pores; 25 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (5 to 10 cm thick)

Bt1--10 to 20 cm; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; moderate coarse angular blocky structure; hard, friable, very sticky and very plastic; common very fine and few fine roots; common very fine, few fine tubular pores; common distinct clay films on faces of peds and lining pores; 5 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (8 to 23 cm thick)

Bt2--20 to 41 cm; brown (10YR 4/3) clay, dark brown (10YR 3/3) moist; strong medium prismatic structure; very hard, very firm, very sticky and very plastic; common very fine roots between peds, few fine and medium roots throughout; few very fine tubular pores; common distinct clay films on faces of peds; 10 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (13 to 38 cm thick)

2Bt3--41 to 56 cm; light brownish gray (2.5Y 6/2) gravelly clay, dark grayish brown (2.5Y 4/2) moist; moderate fine and medium prismatic structure; very hard, very firm, very sticky and very plastic; common very fine roots between peds; few very fine interstitial pores; common distinct clay films on faces of peds; about 20 percent of horizon has rock structure; 10 percent gravel and 5 percent cobbles; neutral (pH 7.3); abrupt smooth boundary. (13 to 38 cm thick)

2Bt4--56 to 71 cm; light gray (2.5Y 7/2) silty clay, grayish brown (2.5Y 5/2) moist; weak fine and medium prismatic structure; very hard, very firm, very sticky and very plastic; common very fine roots; few very fine interstitial pores; many pressure faces; about 35 percent of horizon has rock structure; neutral (pH 7.3); clear wavy boundary. (0 to 25 cm thick)

2Cr--71 to 155 cm; light gray (2.5Y 7/2) weathered tuffaceous shale; few very fine roots along fracture planes; violently effervescent.

TYPE LOCATION: Elko County, Nevada; about 21 miles north of Wells near Antelope Peak; 900 feet south and 250 feet east of the northwest corner of section 1, T. 40 N., R. 61 E.; USGS Black Butte NE 7.5 minute topographic quadrangle; latitude 41 degrees 23 minutes 23 seconds N and longitude 115 degrees 02 minutes 23 seconds W; WGS84 Decimal Degrees 41.3897222 latitude, -115.0397222 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist, dry from about mid-July to October; xeric moisture regime that borders on aridic.
Mean annual soil temperature: 6 to 8 degrees C.
Mollic epipedon thickness: 28 to 50 cm, includes the Bt1 horizon.
Depth to bedrock: 50 to 100 cm to a paralithic contact. The paralithic materials below the contact are tuff, tuffaceous siltstone, or tuffaceous shale.

Particle-size control section - Clay content: averages 40 to 60 percent.
Rock fragments: averages 5 to 20 percent, mainly gravel. Lithology of fragments are tuff.

A horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Clay content: 20 to 35 percent.
Organic matter content: 2 or 3 percent.

Bt horizons
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Texture: Clay or gravelly clay.
Clay content: 40 to 60 percent.
Structure: Moderate or strong angular blocky or prismatic.
Organic matter content: 1 to 3 percent.

2Bt horizons
Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4, dry or moist.
Texture: Silty clay, clay, or gravelly clay loam.
Clay content: 35 to 55 percent.
Structure: Weak to strong angular blocky or prismatic.
Reaction: Neutral or moderately alkaline.
Other features: These horizons are residual and commonly have rock structure in 10 to 40 percent by volume of the matrix. Pararock fragments of shale or siltstone may occur as paragravel or parachanners.

COMPETING SERIES: These are the Bridgecreek, Deer Creek, Eoj, Goodington, Harkers, Lynnbow, Mohocken, Norcan, and Rands series.

Bridgecreek soils have 15 to 40 cm thick Bw horizons with 30 to 40 percent clay that overlie 15 to 30 cm thick argillic horizons. Deer Creek, Eoj, Harkers, Norcan, and Rands soils are very deep. Goodington soils are deep to lithic contacts. Lynnbow soils are deep to paralithic contacts. Mohocken soils have 18 to 25 cm thick mollic epipedons and 20 to 35 percent rock fragments in the particle-size control section.

GEOGRAPHIC SETTING: Coser soils are on hills, mountains, and pediments. These soils formed in colluvium over residuum derived from tuff and tuffaceous sedimentary rocks. Slopes are 4 to 50 percent. Elevations range from 1,710 to 2,290 meters in Nevada and are as low as 1,465 meters in Idaho. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 400 mm, mean annual temperature is 5 to 7 degrees C, and the frost-free period is 70 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cleavage, Cotant, Eboda, Lerrow, and McIvey soils. Cleavage soils are 36 to 50 cm deep to bedrock. Cotant soils are 30 to 50 cm to paralithic contacts. Eboda soils have 25 to 35 percent clay in the particle-size control section. Lerrow soils lack an abrupt clay increase between the A and Bt horizons. McIvey soils are very deep.

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

USE AND VEGETATION: Coser soils are used for rangeland and wildlife habitat. The present vegetation is mainly low sagebrush, Idaho fescue, and Sandberg's bluegrass.

DISTRIBUTION AND EXTENT: Northeastern Nevada and southwestern Idaho. These soils are moderately extensive. MLRA 25.

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

SERIES ESTABLISHED: Elko County (Northeast Part), Nevada, 1986.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 41 cm (A, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 10 to 71 cm (Bt1, Bt2, 2Bt3, and 2Bt4 horizons).
Palexerolls great group feature - The abrupt clay increase of more than 15 percent at 10 cm (between A and Bt1 horizons).
Paralithic contact - The boundary at 71 cm to underlying soft, weathered bedrock (2Cr layer).
Particle size control section - The zone from 10 to 60 cm (Bt1, Bt2, and 2Bt3 and part of the 2Bt4 horizons).

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National Cooperative Soil Survey
U.S.A.