LOCATION OSOBB                   NV

Established Series
Rev. ELS/WED/JVC
02/2012

OSOBB SERIES

The Osobb series consists of very shallow and shallow to a duripan, well drained soils that formed in residuum and colluvium derived from volcanic rocks. Osobb soils are on hills and plateaus. Slopes are 4 to 50 percent. The mean annual precipitation is about 125 mm and the mean annual temperature is about 10 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic, shallow Typic Haplodurids

TYPICAL PEDON: Osobb very fine sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 3 cm; light brownish gray (10YR 6/2) very fine sandy loam, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; 5 percent stones; slightly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 5 cm thick)

A2--3 to 10 cm; light brownish gray (10YR 6/2) gravelly fine sandy loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine and fine and few medium tubular pores; 5 percent cobbles and 20 percent gravel; slightly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (5 to 13 cm thick)

Bk1--10 to 28 cm; pale brown (10YR 6/3) very fine sandy loam, brown (10YR 4/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; 40 percent cobbles and 15 percent gravel; secondary carbonates segregated as few medium and coarse coats on rock fragments; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (8 to 25 cm thick)

Bk2--28 to 43 cm; pale brown (10YR 6/3) very cobbly fine sandy loam, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine and fine roots; many very fine and fine interstitial pores; 45 percent cobbles and 10 percent gravel; secondary carbonates segregated as common medium to very coarse coats on rock fragments; violently effervescent; very strongly alkaline (pH 9.4); abrupt wavy boundary. (8 to 20 cm thick)

Bqkm--43 to 46 cm; very pale brown (10YR 8/3) cemented material, pale brown (10YR 6/3) moist; massive; extremely hard, extremely firm; indurated by secondary silica and carbonates; violently effervescent; very strongly alkaline (pH 9.4). (0.15 to 5 cm thick)

R--46 cm; rhyolitic tuff.

TYPE LOCATION: Churchill County, Nevada; about 15 miles south of Fallon in the White Throne Mountains; approximately 1,900 feet south of the northeast corner of section 15, T. 16 N., R. 29 E., USGS Carson Lake 7.5 minute topographic quadrangle; latitude 39 degrees 15 minutes 2 seconds N and longitude 118 degrees 42 minutes 27 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and early spring, dry for the remainder of the year; typic aridic soil moisture regime.
Mean annual soil temperature: 12 to 14 degrees C.
Depth to thin, indurated duripan: 20 to 48 cm.
Depth to bedrock: 23 to 50 cm to a lithic contact.

Particle-size control section - Clay content: 12 to 18 percent.
Rock fragments: 55 to 80 percent, mostly cobbles or stones. Lithology of fragments is volcanic rocks such as tuff, basalt, or rhyolite.

A horizon
Value: 6 through 8 dry, 4 through 6 moist.
Chroma: 2 or 3, dry or moist.
Reaction: Slightly alkaline to strongly alkaline.
Effervescence: Noneffervescent through violently effervescent.

Bk horizons
Value 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Structure: Subangular blocky or horizons are massive.
Texture: Loam, fine sandy loam or very fine sandy loam.
Reaction: Moderately alkaline through very strongly alkaline.
Identifiable secondary carbonates: Carbonates are segregated as medium to very coarse coats on rock fragments.
Calcium carbonate equivalent: 5 to 10 percent.

COMPETING SERIES: These are the Osoll, Otomo, Pahroc, and Treadwell series.

Osoll soils have lithic contacts between depths of 50 and 100 cm. Otomo, Pahroc, and Treadwell soils do not have bedrock within 150 cm and occur on fan remnants.

GEOGRAPHIC SETTING: Osobb soils are on hills and plateaus. They formed in residuum and colluvium derived from volcanic rocks. Slopes are 4 to 50 percent. Elevations range from 1340 to 2140 meters. The climate is arid with cool, moist winters and hot, dry summers. The mean annual precipitation is 100 to 200 mm, the mean annual temperature is 10 to 12 degrees C., and the frost-free period is 80 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Celeton, Gabbs and Pirouette soils. Celeton soils are loamy, very shallow and shallow to paralithic contacts of diatomite, and have ochric epipedons. Gabbs soils are loamy-skeletal and are moderately deep to indurated duripans. Pirouette soils are loamy-skeletal, shallow to thin, indurated duripans and have natric horizons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high saturated hydraulic conductivity.

USE AND VEGETATION: Osobb soils are used for livestock grazing and wildlife habitat. The vegetation is mainly shadscale, Bailey's greasewood, Nevada ephedra, bud sagebrush, and galleta.

DISTRIBUTION AND EXTENT: Western Nevada. These soils are moderately extensive. MLRAs 27 and 29.

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

SERIES ESTABLISHED: Churchill County, Nevada (Fallon-Fernley Area), 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1, A2and part of the Bk1 horizons).
Identifiable secondary carbonates - The zone from 10 to 46 cm (Bk1, Bk2, and Bqkm horizons).
Indurated duripan - The zone from 43 to 46 cm (Bqkm horizon).
Lithic contact - The boundary to underlying hard bedrock at 46 cm (R layer).
Particle-size control section - The zone from 25 to 43 cm (Bk2 horizon and part of the Bk1 horizon).

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National Cooperative Soil Survey
U.S.A.