LOCATION POCAN                   NV

Established Series
Rev. RLH/MJZ/TM/JBF
03/2016

POCAN SERIES

The Pocan series consists of deep, well drained soils that formed in colluvium and residuum derived from quartzite, slate, shale, sandstone and chert. Pocan soils are on side slopes of hills and mountains. Slopes are 30 to 50 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Xeric Haplocambids

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

A1--0 to 8 cm; pale brown (10YR 6/3) loam, dark brown (10YR 3/3) moist; weak fine and moderate very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine fibrous roots; many very fine interstitial pores; 1 percent stones; neutral (pH 7.2); clear smooth boundary. (5 to 15 cm thick)

A2--8 to 25 cm; pale brown (10YR 6/3) loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few fine and common very fine roots; many very fine interstitial pores; slightly alkaline (pH 7.4); clear smooth boundary. (13 to 28 cm thick)

Bw--25 to 66 cm; yellowish brown (10YR 5/4) gravelly loam, brown (10YR 4/3) moist; moderate medium angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine tubular and interstitial pores; 15 percent fine gravel; slightly alkaline (pH 7.4); abrupt smooth boundary. (28 to 53 cm thick)

Bk--66 to 122 cm; light yellowish brown (10YR 6/4) gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate medium angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and very fine roots; common very fine tubular and interstitial pores; 20 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); abrupt irregular boundary. (50 to 64 cm thick)

2R--122 cm; quartzite.

TYPE LOCATION: Pershing County, Nevada; approximately 25 miles southeast of Winnemucca, about 1,000 feet south and 1,000 feet east of the northwest corner of section 28, T. 32 N., R. 39.; USGS Panther Canyon 7.5 minute topographic quadrangle; latitude 40 degrees 37 minutes 23 seconds N and longitude 117 degrees 36 minutes 8 seconds W; WGS84 Decimal Degrees 40.6230556 latitude, -117.6022222 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in winter and spring, dry early June through early November; aridic soil moisture regime bordering on xeric.
Mean annual soil temperature; 8 to 11 degrees C.
Depth to carbonates: 50 to 97 cm.
Depth to bedrock: 100 to 150 cm.
Other features: Indurated duripans are below 100 cm in some pedons

Particle-size control section - Clay content: 18 to 25 percent.
Rock fragments: 5 to 35 percent.

A horizon
Value: 5 through 7 dry, 3 through 5 moist.
Reaction: Neutral or slightly alkaline.
Remarks: Horizons with mollic colors do not meet the thickness requirements for a mollic epipedon.

Bw horizon
Value: 5 or 6 dry.
Texture: Loam or gravelly loam.
Rock fragments: 5 to 35 percent.
Structure: Angular or subangular blocky.
Reaction: Neutral or slightly alkaline.
Other features: The lower 5 or 8 cm of the Bw horizon is slightly effervescent in some pedons.

Bk horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 3 or 4.
Rock fragments: 15 to 35 percent.
Structure: Angular or subangular blocky; lower subhorizons are massive in some pedons.
Consistence: Soft or slightly hard, dry; very friable or friable, moist.
Reaction: Moderately alkaline or strongly alkaline.
Other features: Some pedons have up to 20 percent durinodes or weakly silica-cemented plates.

COMPETING SERIES: These are the Ardnas, Eastable, Ferdelford, Legler, North Powder, and Oxman series.

Ardnas soils are very deep and have a moderately alkaline or strongly alkaline cambic horizon that is 23 to 33 cm thick. Eastable soils are very deep and are noncalcareous throughout. Ferdelford soils are calcareous throughout and are 60 to 100 cm deep over a paralithic contact. Legler soils have a particle-size control section with silt loam or silty clay loam that is free of rock fragments. North Powder soils have bedrock at depths of 50 to 100 cm. Oxman soils are calcareous throughout and are 50 to 100 cm thick over paralithic contact to lacustrine sediments.

GEOGRAPHIC SETTING: Pocan soils are on side slopes of hills and mountains. These soils formed in colluvium and residuum derived from quartzite, slate, shale, sandstone, and chert. Slopes are 30 to 50 percent. Elevations are 1,375 to 1,925 meters. The climate is cool, semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 mm; mean annual temperature is 7 to 10 degrees C, and the frost-free season is 100 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Golsum and Trunk soils. These soils have an argillic horizon and bedrock at a depth of 50 to 100 cm.

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

USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly Wyoming big sagebrush, rabbitbrush, Sandberg bluegrass, bottlebrush squirreltail, and phlox.

DISTRIBUTION AND EXTENT: North-central Nevada. These soils are not extensive. MLRA 24.

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

SERIES ESTABLISHED: Pershing County (BLM Sonoma Planning Unit), Nevada. 1974.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to about 18 cm (A1 and the upper part of the A2 horizons).
Cambic horizon - The zone from 25 to 66 cm (Bw horizon).
Lithic contact - The boundary at 122 cm (R horizon).
Xeric intergrade - Meets organic carbon requirement for xeric.
Particle-size control section - The zone from 25 to 100 cm.

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National Cooperative Soil Survey
U.S.A.