LOCATION AFFEY                   NV

Established Series
Rev. ARW/DWW/JVC/JBF
02/2018

AFFEY SERIES

The Affey series consists of very deep, moderately well drained soils that formed in alluvium derived from mixed rocks, loess, and volcanic ash. Affey soils are on fan remnants. Slopes are 4 to 15 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 6 degrees C.

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

TYPICAL PEDON: Affey gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 35 percent gravel.

A1--0 to 23 cm; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; many very fine and few fine and medium tubular pores; 20 percent gravel; slightly alkaline (pH 7.6); clear wavy boundary. (13 to 30 cm thick)

A2--23 to 30 cm; grayish brown (10YR 5/2) gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine, fine and medium roots; many very fine and few fine and medium tubular pores; 20 percent gravel; slightly alkaline (pH 7.6); abrupt wavy boundary. (5 to 15 cm thick)

Bt1--30 to 53 cm; brown (10YR 5/3) gravelly clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium angular blocky; hard, firm, moderately sticky and very plastic; few very fine, fine and medium roots; many very fine, common fine and few medium tubular pores; many pressure faces on peds; many very fine manganese concretions; 25 percent gravel; slightly alkaline (pH 7.4); clear wavy boundary. (13 to 30 cm thick)

Bt2--53 to 61 cm; yellowish brown (10YR 5/4) very gravelly clay, dark yellowish brown (10YR 4/4) moist; moderate medium angular blocky structure; hard, firm, very sticky and very plastic; few very fine, fine and medium roots; many very fine, common fine and few medium tubular pores; many pressure faces on peds; many very fine manganese concretions; 55 percent gravel; slightly alkaline (pH 7.4); abrupt wavy boundary. (0 to 10 cm thick)

Btk1--61 to 79 cm; yellowish brown (10YR 5/4) very gravelly clay, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure; hard, firm, very sticky and very plastic; few very fine, fine, medium and coarse roots; many very fine, common fine, and few medium tubular pores; many pressure faces on peds; many very fine manganese concretions; common fine seams of secondary carbonate; 35 percent gravel; noneffervescent matrix; slightly alkaline (pH 7.6); abrupt wavy boundary. (13 to 25 cm thick)

Btk2--79 to 86 cm; yellowish brown (10YR 5/4) very gravelly clay, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure; hard, firm, very sticky and very plastic; few very fine, fine, medium and coarse roots; many very fine, common fine and few medium tubular pores; many pressure faces on peds; many very fine manganese concretions; 40 percent gravel and 5 percent cobbles; violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 15 cm thick)

Bqk--86 to 152 cm; very pale brown (10YR 7/3) extremely gravelly clay loam, brown (10YR 4/3) moist; massive; hard, firm and brittle, slightly sticky and slightly plastic; continuous brittle matrix; many very fine and fine tubular pores; many lenticular zones which are strongly silica-cemented and common thin to moderately thick silica pendants on undersides of gravel; 65 percent gravel and 5 percent cobbles; common fine seams and filaments, and few fine soft masses of secondary carbonate; violently effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION: Elko County, Nevada; about 30 miles north of Pequop; about 7,900 feet north and 1,000 feet east of the northwest corner of section 1, T. 42 N., R. 65 E.; USGS Knoll Mountain SE 7.5 minute topographic quadrangle; latitude 41 degrees 34 minutes 52 seconds N and longitude 114 degrees 33 minutes 52 seconds W; WGS84 Decimal Degrees 41.5811111 latitude, -114.5644444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Moist in the winter and spring, dry from early July through October; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon: 25 to 40 cm, may include the upper part of the argillic horizon in some pedons.
Depth to identifiable secondary carbonates: 46 to 100 cm.
Depth to base of argillic horizon and upper boundary of horizon with weak silica cementation: 66 to 100 cm.

Particle-size control section - Clay content: Averages 35 to 45 percent.
Rock fragments: Averages 35 to 50 percent, mainly gravel with up to 10 percent cobbles and stones. Lithology of fragments are mixed, but may be dominated by volcanic rocks such as tuff, andesite, and rhyolite.

A horizon
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Reaction: Neutral or slightly alkaline.

Bt horizons
Hue: 7.5YR or 10YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4.
Texture: Gravelly clay loam in the Bt1 horizon and very gravelly clay loam or very gravelly clay in the Bt2 horizon.
Clay content: 35 to 40 in the Bt1 horizon and 35 to 50 percent in the Bt2 horizon.
Structure: Prismatic or angular blocky.
Reaction: Neutral or slightly alkaline.
Redoximorphic features: Redox concentrations of manganese are present as many very fine concretions.

Btk horizons
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 through 5 moist.
Clay content: 40 to 50 percent.
Structure: Prismatic or angular blocky.
Reaction: Slightly alkaline or moderately alkaline.
Calcium carbonate equivalent: 1 to 3 percent.
Redoximorphic features: Redox concentrations of manganese are present as many very fine concretions.

Bqk horizons
Hue: 10YR or 7.5YR.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Consistence: Hard or very hard and brittle.
Reaction: Moderately alkaline or strongly alkaline.
Silica cementation: Continuously brittle matrix, with up to 50 percent thin to thick zones of discontinuous strongly silica-cemented material.
Calcium carbonate equivalent: 1 to 10 percent.

COMPETING SERIES: This is the Homestake series. Homestake soils have 50 to 70 percent rock fragments in the upper 50 cm of the argillic horizon, identifiable secondary carbonates between 33 and 50 cm, and do not have manganese concretions within the argillic horizon.

GEOGRAPHIC SETTING: Affey soils are on fan remnants. They typically occur on summit and shoulder positions. They formed in alluvium derived from mixed rocks, loess, and volcanic ash. Slopes are 4 to 15 percent. Elevations range from 1,710 to 2,320 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 300 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 70 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cleavage and Gollaher soils. Cleavage soils are loamy-skeletal, shallow to lithic contacts, and have mollic epipedons and argillic horizons. Gollaher soils are loamy-skeletal, very shallow to lithic contacts, and have carbonatic mineralogy.

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

USE AND VEGETATION: Affey soils are used for rangeland and wildlife habitat. The present vegetation is mainly Wyoming big sagebrush, Nevada bluegrass, bottlebrush squirreltail, Indian ricegrass, and scattered Utah juniper.

DISTRIBUTION AND EXTENT: Northeastern Nevada. These soils are not extensive with about 2,700 acres of the series mapped to date. MLRA 25.

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

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

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 30 cm (A1 and A2 horizons).
Argillic horizon - The zone from 30 to 86 cm (Bt1, Bt2, Btk1, and Btk2 horizons).
Duric feature - The zone from 38 to 152 cm (Bqk horizon).
Particle-size control section - The zone from 30 to 80 cm (Bt1, Bt2, Btk1 and part of the Btk2 horizons).

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National Cooperative Soil Survey
U.S.A.