LOCATION BOBS                    NV

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

BOBS SERIES

The Bobs series consists of shallow to a petrocalcic horizon, well drained soils that formed in alluvium derived from limestone or dolomite with a component of loess high in volcanic ash. Bobs soils are on fan remnants. Slopes are 2 to 30 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy, carbonatic, frigid, shallow Petrocalcidic Palexerolls

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

A1--0 to 10 cm; grayish brown (10YR 5/2) gravelly loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many fine interstitial pores; 20 percent gravel; violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (3 to 18 cm thick)

A2--10 to 30 cm; grayish brown (10YR 5/2) gravelly loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine interstitial pores; 25 percent gravel; violently effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (13 to 33 cm thick)

Bkm--30 to 64 cm; very pale brown (10YR 8/2) petrocalcic horizon, light gray (10YR 7/2) moist; massive with very thin (less than 1 millimeter thick) continuous laminae on the upper surface; extremely hard, extremely firm, indurated by secondary calcium carbonates; few very fine interstitial pores but none in laminae; violently effervescent; strongly alkaline (pH 8.5).

TYPE LOCATION: Eureka County, Nevada; about 14 miles northeast of Dunphy along the southwest flank of Richmond Mountain; about 800 feet south and 500 feet west of the northeast corner of section 3, T. 34 N., R. 50 E.; USGS Welches Canyon 7.5 minute topographic quadrangle; latitude 40 degrees 51 minutes 24 seconds N and longitude 116 degrees 18 seconds 43.3 seconds W; WGS84 Decimal Degrees 40.8566667 latitude, -116.3116667 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry; moist in the winter and spring, dry summer and fall; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 18 to 36 cm.
Depth to petrocalcic horizon: 25 to 50 cm.
Reaction: Moderately alkaline or strongly alkaline.

Particle-size control section - Clay content: 10 to 20 percent.
Rock fragments: 15 to 35 percent, mainly gravel. Lithology of fragments is limestone, dolomite, and detached fragments of petrocalcic horizon.

A1 horizon
Value: 4 or 5 dry, 2 through 4 moist; a moist value of 4 is only in thin A1 horizons and the upper 18 cm when mixed has moist value of 2 or 3.
Chroma: 1 through 3, dry or moist.
Organic matter content: 1 to 3 percent.
Calcium carbonate equivalent: 20 to 35 percent in the less than 2 millimeter fraction; 30 to 50 percent in the less than 20 millimeter fraction.

A2 horizon
Value: 2 or 3 moist.
Chroma: 1 through 3, dry or moist.
Texture: Gravelly loam, gravelly very fine sandy loam, or gravelly silt loam.
Organic matter content: 1 or 2 percent.
Calcium carbonate equivalent: 35 to 45 percent in the less than 2 millimeter fraction; 40 to 60 percent in the less than 20 millimeter fraction.

Bk horizon (when present)
Hue: 10YR or 7.5YR.
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 through 4, dry or moist.
Structure: Angular blocky or subangular blocky.
Texture: Gravelly loam, gravelly very fine sandy loam, or gravelly silt loam.
Calcium carbonate equivalent: 35 to 45 percent in the less than 2 mm fraction; 40 to 60 percent in the less than 20 mm fraction.
Other features: Rock fragments are coated with secondary carbonates.

Bkm horizon
Hue: 7.5YR or 10YR.
Value: 6 through 8 dry, 5 through 7 moist.
Chroma: 1 through 4, dry or moist.
Other features: Some pedons have 10 to 35 percent krotovinas 3 to 30 cm in diameter.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Bobs soils are on fan remnants. These soils formed in alluvium derived from limestone and dolomite with a small component of loess high in volcanic ash. Slopes are 2 to 30 percent. Elevations range from 1,675 to 2,285 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 360 mm, 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 Chen, Hopeka, and Ramires soils. Chen and Ramires soils have argillic horizons. Hopeka soils have ochric epipedons and are shallow to lithic contacts.

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

USE AND VEGETATION: Bobs soils are used for livestock grazing and wildlife habitat. The present vegetation is mainly bluebunch wheatgrass, basin wildrye, Indian ricegrass, Sandberg's bluegrass, big sagebrush, antelope bitterbrush, and arrowleaf balsamroot. Some areas have scattered open stands of Utah juniper and singleleaf pinyon.

DISTRIBUTION AND EXTENT: Central and eastern Nevada. These soils are moderately extensive. MLRA 28B

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

SERIES ESTABLISHED: Eureka 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 30 cm (A1 and A2 horizons).
Petrocalcic horizon - The zone from 30 to 64 cm (Bkm horizon).
Particle-size control section - The zone from the soil surface to 30 cm (A1 and A2 horizons).

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National Cooperative Soil Survey
U.S.A.