LOCATION ALPHA                   NV

Established Series
Rev. WMA/ELS/JVC/JBF
11/2016

ALPHA SERIES

The Alpha series consists of deep, well drained soils that formed in residuum derived from basalt with surficial mantles of loess. Alpha soils are on hills. Slopes are 8 to 30 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Duridic Haploxerolls

TYPICAL PEDON: Alpha loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 8 cm; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; soft, friable, slightly sticky and slightly plastic; many very fine roots; many very fine interstitial pores; 10 percent gravel; neutral (pH 6.6); abrupt wavy boundary. (3 to 20 cm thick)

A2--8 to 23 cm; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; few medium and fine, and many very fine roots; many fine and very fine interstitial pores; 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (8 to 20 cm thick)

AB--23 to 43 cm; grayish brown (10YR 5/2) loam, dark brown (10YR 3/3) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; few medium and fine, and common very fine roots; many fine and very fine tubular pores; 10 percent gravel; neutral (pH 6.6); clear smooth boundary. (5 to 25 cm thick)

Bw--43 to 91 cm; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; moderate medium and fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; few medium, fine , and very fine roots; many fine and very fine tubular pores; 15 percent gravel; neutral (pH 7.2); clear smooth boundary. (25 to 60 cm thick)

Bkq--91 to 127 cm; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; massive; hard, friable, moderately sticky and moderately plastic; few very fine roots; many very fine interstitial and tubular pores; 15 percent gravel; 30 percent hard and firm durinodes; strongly effervescent; secondary carbonates segregated as very pale brown (10YR 8/2) masses and veins; strongly alkaline (pH 8.6); clear wavy boundary. (15 to 46 cm thick)

R--127 cm; unweathered basalt.

TYPE LOCATION: Elko County, Nevada; southeast of Red Rock Summit; approximately 1,800 feet south and 1,700 feet west of the northeast corner of section 33, T. 27 N., R. 54 E.; USGS Garcia Flat 7.5 minute topographic quadrangle; latitude 40 degrees 10 minutes 53 seconds N and longitude 115 degrees 53 minutes 39 seconds W; WGS84 Decimal Degrees 40.1813889 latitude -115.8941667 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: These soils are usually moist in winter and spring; dry in summer and fall; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mean summer soil temperature: 16 to 17 degrees C.
Mollic epipedon thickness: 25 to 46 cm; usually includes transitional A3 or AB horizons.
Depth to base of cambic horizon: 50 to 90 cm thick.
Depth to bedrock: 100 to 150 cm to a lithic contact. The bedrock contact is normally coated with thin discontinuous layers of silica and carbonates.

Particle-size control section - Clay content: Averages 20 to 30 percent.
Rock fragments: 5 to 15 percent.

A horizons
Value: 4 or 5 dry, 2 or 3 moist.
Structure: Weak medium platy or granular structure.

AB horizon
Texture: Loam or clay loam, modified by up to 20 percent gravel or cobbles in some pedons.
Structure: Weak or moderate coarse subangular to fine angular blocky structure.

Bkq horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3 dry or moist.
Identifiable secondary carbonates: Few or common masses and seams.
Durinodes: 20 to 50 percent.
Reaction: Moderately alkaline or strongly alkaline.
Effervescence: Slightly effervescent or strongly effervescent.

COMPETING SERIES: There are no other series in this family.

GEOGRAPHIC SETTING: Alpha soils are on north facing rolling hilly areas at elevations of 1,830 to 2,140 meters. Slope gradients are 8 to 30 percent. The soils formed in residuum derived from basalt bedrock with additions of ashy loess on the surface. The average annual precipitation is 250 to 300 mm coming mostly as snow. The mean annual temperature is 6 to 8 degrees C. The frost free season is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ridit soils and the competing Holtle soils. Ridit soils have ochric epipedons, loamy, skeletal particle-size control sections, and are shallow to moderately deep over duripans.

DRAINAGE AND PERMEABILITY: Well drained; moderate or moderately slow permeability; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Alpha soils are used for rangeland and wildlife habitat. Vegetation is big sagebrush, squirreltail, Sandberg's bluegrass, and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: Northeastern Nevada. Alpha soils are not extensive with about 4,800 acres of the series mapped to date. MLRA 28B.

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

SERIES ESTABLISHED: Elko County (Diamond Valley Area), Nevada, 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 43 cm (A1, A2, and AB horizons).
Cambic horizon - The zone from 43 to 91 cm (Bw horizon).
Identifiable secondary carbonates and durinodes - The zone from 91 to 127 cm (Bkq horizon).
Lithic contact - The boundary at 127 cm to underlying unweathered bedrock (R layer).
Particle-size control section - The zone from 25 to 100 cm (Bw horizon and parts of the AB and Bkq horizons).

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National Cooperative Soil Survey
U.S.A.