LOCATION PUROB                   NV

Established Series
Rev. LJL/TM/RLB/ET
12/2015

PUROB SERIES

The Purob series consists of shallow to a petrocalcic, well drained soils that formed in alluvium derived from limestone. Purob soils are on ballenas and fan remnants. Slope ranges from 2 to 50 percent. The mean annual precipitation is about 200 millimeters (8 inches) and the mean annual air temperature is about 12 degrees C. (53 degrees F.).

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, mesic, shallow Calcic Petrocalcids

TYPICAL PEDON: Purob extremely gravelly loam - rangeland and wildlife habitat. Colors are for dry soil unless otherwise noted. The soil surface is covered by approximately 60 percent gravel, 4 percent cobbles, 1 percent stones.

A--0 to 8 centimeters (0 to 3 inches); very pale brown (10YR 7/4) extremely gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate thin and medium platy structure; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine, fine and medium vesicular and few fine tubular pores; 60 percent gravel, 4 percent cobbles, 1 percent stones; violently effervescent (20 percent calcium carbonate equivalent in the fine earth fraction); moderately alkaline (pH 8.2 ); clear smooth boundary. (5 to 10 centimeters thick)

Bk1--8 to 20 centimeters (3 to 8 inches); yellowish brown (10YR 5/4) very gravelly loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine, fine and few medium roots; common very fine and few fine interstitial and tubular pores; 40 percent gravel (mainly pan fragments); violently effervescent (15 percent calcium carbonate equivalent in the fine earth fraction); moderately alkaline (8.2 pH); clear wavy boundary. (0 to 18 centimeters thick)

Bk2--20 to 41 centimeters (8 to 16 inches); brown (7.5YR 5/4) very gravelly loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and few fine and medium roots; few very fine and fine interstitial and tubular pores; 50 percent gravel, 5 percent cobbles (mainly pan fragments); violently effervescent (35 percent calcium carbonate equivalent in the fine earth fraction); moderately alkaline (pH 8.4); clear wavy boundary. (15 to 30 centimeters thick)

Bk3--41 to 48 centimeters (16 to 19 inches); light yellowish brown (10YR 6/4) extremely gravelly clay loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine roots; few very fine and fine interstitial and tubular pores; disseminated calcium carbonate; 55 percent gravel (mainly pan fragments), 7 percent cobbles; violently effervescent (75 percent calcium carbonate equivalent in the fine earth fraction); moderately alkaline (pH 8.4); abrupt broken boundary. (0 to 13 centimeters thick)

Bkqm--48 to 152 centimeters (19 to 60 inches); white (10YR 8/1) and very pale brown (10YR 8/3) very strongly cemented and indurated petrocalcic, very pale brown (10YR 8/2) to very pale brown (10YR 7/3) moist; massive; rigid and very rigid.

TYPE LOCATION: Clark County, Nevada; approximately 0.8 kilometers (1/2 mile) south of State Route 157 and 0.4 kilometers (1/4 mile) east of the Toiyabe National Forest boundary in Kyle Canyon on the east side of the Spring Mountain Range; about 625 meters (2,050 feet) south and 549 meters (1,800 feet) east of the northwest corner of sec. 29, T. 19 S., R. 58 E.; USGS Angel Peak, NV 7.5 minute topographic quadrangle; 36 degrees, 16 minutes, 18.7 seconds north latitude and 115 degrees, 30 minutes, 24.9 seconds west longitude; UTM 11s, 634231e, 4015116n; NAD 83.

RANGE IN CHARACTERISTICS:

Soil moisture: Usually dry, moist in some part for short periods during winter and early spring and for 10 to 20 days cumulative between July through October following convection storms. The soils have a typic-aridic soil moisture regime.

Soil temperature: 12 to 14 degrees C. (53 to 58 degrees F.).

Depth to calcic horizon: 10 to 25 centimeters (4 to 10 inches).

Depth to petrocalcic horizon: 36 to 50 centimeters (14 to 20 inches).

Control section
Clay content: Averages 12 to 27 percent; non-carbonate clay is 7 to 18 percent.
Rock fragments: 35 to 70 percent, mainly pan fragments.
Calcium carbonate equivalent in the less than 20 millimeter fraction: Averages 40 to 80 percent.

A horizon:
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 2 through 4.

Bk1 horizon:
Value: 5 or 6 dry.
Rock fragments: 20 to 50 percent, mainly pan fragments.
Structure: Weak or moderate subangular blocky.
Effervescence: Strongly effervescent or violently effervescent.
Calcium carbonate equivalent in the fine earth fraction: 10 to 25 percent.

Bk2 and Bk3 horizons:
Chroma: 3 or 4.
Carbonate clay content: Upper part has 1 to 10 percent and the lower part (when present) has 10 to 25 percent.
Texture: Averages loam; some subhorizons include clay loam.
Rock fragments: 35 to 70 percent, mainly pan fragments.
Effervescence: Strongly effervescent or violently effervescent.
Calcium carbonate equivalent in the fine earth fraction: 30 to 80 percent.

Bkqm horizon:
Value: 7 or 8 dry.
Structure: Massive or platy.
Pan thickness: Greater than 92 centimeters (36 inches) thick.
Cementation class: Very strongly cemented or indurated.

COMPETING SERIES: These are the Goodwater (NV), Spager (UT) and Wamp (NV) series. Goodwater and Wamp soils have an aridic bordering on ustic soil moisture regime. Spager soils have an aridic bordering on xeric soil moisture regime.

GEOGRAPHIC SETTING: Purob soils are on ballenas and fan remnants. These soils formed in alluvium derived from limestone. Slope ranges from 2 to 50 percent. Elevations are 1,160 to 2,170 meters (3,800 to 7,100 feet). The climate is warm and arid with cool, moist winters and hot, dry summers. The mean annual precipitation is 175 to 280 millimeters (7 to 11 inches); mean annual air temperature is 11 to 13 degrees C. (51 to 56 degrees F.), and the frost-free season is 130 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Irongold series. Irongold soils have a thermic soil temperature regime and contain less than 35 percent rock fragments.

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

USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly blackbrush, mohave yucca and desert needlegrass.

DISTRIBUTION AND EXTENT: Mojave Desert of southern Nevada; MLRA 30. These soils are moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: PHOENIX, ARIZONA

SERIES ESTABLISHED: Nye County, Nevada, Southwest Part, 1985. The name is coined. The series was moved from Nye County, Nevada to Clark County, Nevada to better represent the new concept and classification.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 18 centimeters (0 to 7 inches) (A horizon and part of the Bk1 horizon).
Calcic horizon - 20 to 48 centimeters (8 to 19 inches) (Bk2 and Bk3 horizons).
Petrocalcic horizon - 48 to 152 centimeters (19 to 60 inches) (Bkqm horizon).
Particle-size control section - 25 to 48 centimeters (10 to 19 inches) (Part of the Bk2 and Bk3 horizons).

ADDITIONAL DATA: Sampled on October 4, 2004, by NRCS Nevada staff, samples sent to NSSL, Lincoln, NE. Pedon ID is S04NV-003-004.

Responsibility for this series was transferred from Davis to Phoenix 12/2015. The last revision to the series was 6/2011. ET

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National Cooperative Soil Survey
U.S.A.