LOCATION COSER NV+IDEstablished Series
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 pebbles.
A--0 to 4 inches; 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, many fine, and few medium vesicular pores; 25 percent pebbles; neutral (pH 6.8); abrupt wavy boundary. (2 to 8 inches thick)
Bt1--4 to 8 inches; 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, few fine roots; common very fine, few fine tubular pores; common distinct clay films on faces of peds and lining pores; 5 percent pebbles; neutral (pH 6.8); abrupt smooth boundary. (3 to 9 inches)
Bt2--8 to 16 inches; 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 and few fine and few medium roots throughout; few very fine tubular pores; common distinct clay films on faces of peds; 10 percent pebbles; neutral (pH 6.8); abrupt wavy boundary. (5 to 15 inches thick)
2Bt3--16 to 22 inches; 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 pebbles and 5 percent cobbles; neutral (pH 7.3); abrupt smooth boundary. (5 to 15 inches thick)
2Bt4--22 to 28 inches; 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 pores; many pressure faces; about 35 percent of horizon has rock structure; neutral (pH 7.3); clear wavy boundary. (0 to 10 inches thick)
2Cr--28 to 61 inches; 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; 41 degrees 23 minutes 23 seconds north latitude and 115 degrees 02 minutes 19 seconds west longitude, NAD 27.
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 - 43 to 47 degrees F.
Mollic epipedon thickness - 11 to 20 inches, includes the Bt1 horizon.
Depth to bedrock - 20 to 40 inches to a paralithic contact. The paralithic materials below the contact are tuff, tuffaceous siltstone, or tuffaceous shale.
Control section - Clay content: averages 40 to 60 percent; Rock fragments: averages 5 to 20 percent, mainly pebbles. 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 parapebbles or parachanners.
COMPETING SERIES: These are the Bridgecreek, Deer Creek, Eoj, Goodington, Harkers, Lynnbow, Mohocken, Norcan, and Rands series.
Bridgecreek soils have 6 to 16 inch thick Bw horizons with 30 to 40 percent clay that overlie 6 to 12 inch 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 7 to 10 inch 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 5,600 to 7,500 feet in Nevada and are as low as 4,800 feet in Idaho. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 12 to 16 inches, mean annual temperature is 41 to 45 degrees F., 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 14 to 20 inches deep to bedrock. Cotant soils are 12 to 20 inches 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 PERMEABILITY: Well drained; very high surface runoff; very slow permeability.
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 OFFICE RESPONSIBLE: Reno, Nevada.
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 16 inches (A, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 4 inches to 28 inches (Bt1, Bt2, 2Bt3, and 2Bt4 horizons).
Palexerolls great group feature - The abrupt clay increase of more than 15 percent at 4 inches (between the A and Bt1 horizons).
Paralithic contact - The boundary at 28 inches to underlying soft, weathered bedrock (2Cr layer).
Particle size control section - The zone from 4 inches to 24 inches (Bt1, Bt2, and 2Bt3 horizons and part of the 2Bt4 horizon).