LOCATION PAHRUMP                 NV

Established Series
Rev. HJB/RLB/WED/ET
12/2015

PAHRUMP SERIES

The Pahrump series consists of very deep, well drained soils that formed in lacustrine deposits from lake bed and offshore bar sediments derived from limestone. Pahrump soils are on lake terraces. Slope ranges from 0 to 15 percent. The mean annual precipitation is about 100 millimeters (4 inches) and the mean annual air temperature is about 18 degrees C. (64 degrees F.).

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic Petronodic Haplocalcids

TYPICAL PEDON: Pahrump fine sandy loam - rangeland and wildlife habitat. Colors are for dry soils unless otherwise noted. The soil surface is covered by approximately 30 percent gravel consisting of pan fragments.

A--0 to 5 centimeters (0 to 2 inches); light gray (10YR 7/2) fine sandy loam, pale brown (10YR 6/3) moist; weak coarse platy structure; soft, very friable, nonsticky and nonplastic; few very fine vesicular and many very fine interstitial pores; 10 percent gravel; violently effervescent; strongly alkaline (pH 8.8); abrupt smooth boundary. (5 to 15 centimeters thick)

Bk1--5 to 20 centimeters (2 to 8 inches); very pale brown (10YR 8/2) very fine sandy loam, pale brown (10YR 6/3) moist; massive; soft and slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine interstitial pores; few hard calcium carbonate concretions; violently effervescent; strongly alkaline (pH 9.0); abrupt wavy boundary.

Bk2--20 to 41 centimeters (8 to 16 inches); very pale brown (10YR 8/2) loam, pale brown (10YR 6/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many medium and common very fine and fine roots; few fine tubular and common fine interstitial pores; 10 percent hard, contorted and generally cylindrical calcium carbonate concretions; violently effervescent; very strongly alkaline (pH 9.2); abrupt wavy boundary. (Combined thickness of the Bk horizons is 10 to 46 centimeters.)

2Bk1--41 to 56 centimeters (16 to 22 inches); light gray (10YR 7/2) very gravelly silt loam, light yellowish brown (10YR 6/4) moist; massive; hard, very friable, sticky and slightly plastic; few very fine roots; many very fine tubular pores; 50 percent hard, contorted, branched and generally cylindrical calcium carbonate concretions; violently effervescent; very strongly alkaline (pH 9.2); abrupt irregular boundary.

2Bk2--56 to 81 centimeters (22 to 32 inches); very pale brown (10YR 8/3) very gravelly silty clay loam, light yellowish brown (10YR 6/4) moist; massive; slightly hard and hard, friable, moderately sticky and moderately plastic; common very fine and fine tubular pores; 55 percent hard, contorted, branched and generally cylindrical calcium carbonate concretions; violently effervescent; very strongly alkaline (pH 9.4); abrupt irregular boundary.

2Bk3--81 to 107 centimeters (32 to 42 inches); very pale brown (10YR 8/2) very gravelly silt loam, light yellowish brown (10YR 6/4) moist; massive; hard, very friable, moderately sticky and slightly plastic; common very fine and fine tubular pores; 50 percent hard, contorted, branched calcium carbonate concretions; violently effervescent; very strongly alkaline (pH 9.2); abrupt smooth boundary. (Combined thickness of the 2Bk horizons is 56 to 112 centimeters.)

3C--107 to 155 centimeters (42 to 61 inches); very pale brown (10YR 8/2) very fine sandy loam, pale brown (10YR 6/3) moist; massive; slightly hard, very friable, slightly sticky and nonplastic; few very fine tubular and common very fine interstitial pores; violently effervescent; strongly alkaline (pH 8.8).

TYPE LOCATION: Nye County, Nevada; about 201 meters (660 feet) east and 15 meters (50 feet) north of the southwest corner of sec. 35, T. 19 S., R. 53 E; 36 degrees, 14 minutes, 58 seconds north latitude and 115 degrees, 59 minutes, 39 seconds west longitude; USGS Pahrump, NV 7.5 minute topographic quadrangle; UTM 11; 590385e, 4012070n; NAD83.

RANGE IN CHARACTERISTICS:

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

Soil temperature: 18 to 21 degrees C. (65 to 70 degrees F.).

Depth to calcic horizon: 5 to 25 centimeters (2 to 10 inches).

Depth to petronodic feature: 15 to 50 centimeters (6 to 20 inches).

Control section
Clay content: Averages 18 to 27 percent.
Sand content: Less than 25 percent fine sand through coarse sand in the fine earth fraction.
Rock fragments: Averages 35 to 60 percent, in the form of hard calcium carbonate concretions and nodules. Rock fragment consistence is cemented through indurated.

A horizons:
Value: 5 or 6 moist.
Chroma: 2 through 4.
Calcium carbonate equivalence of the fine earth: 25 to 35 percent.

Bk horizons:
Value: 7 or 8 dry, 5 or 6 moist.
Chroma: 2 through 4.
Texture: Stratified very fine sandy loam or loam.
Clay content: 10 to 18 percent.
Rock fragments: 0 to 10 percent, as hard calcium carbonate concretions and nodules.
Structure: Weak, medium or coarse, subangular blocky or massive.
Consistence: Nonsticky or slightly sticky and nonplastic or slightly plastic.
Calcium carbonate equivalence of the fine earth: 30 to 45 percent.
Reaction: Moderately alkaline through very strongly alkaline.

2Bk horizons:
Value: 7 or 8 dry, 5 or 6 moist.
Chroma: 2 through 4.
Texture: Stratified silt loam, loam or silty clay loam.
Clay content: 18 to 30 percent.
Rock fragments: 35 to 60 percent, as hard calcium carbonate concretions and nodules.
Structure: weak, fine through coarse, subangular blocky, platy or massive.
Consistence: soft through hard, friable or very friable.
Calcium carbonate equivalence of the fine earth: 25 to 60 percent.
Reaction: Moderately alkaline through very strongly alkaline.

3C horizon:
Value: 7 or 8 dry, 5 or 6 moist.
Chroma: 2 through 4.
Texture: Very fine sandy loam or silt loam.
Rock fragments: 0 to 10 percent, as hard calcium carbonate concretions and nodules.
Consistence: Slightly or moderately hard, very friable or friable, and nonplastic or slightly plastic.
Calcium carbonate equivalence of the fine earth: 15 to 25 percent.

COMPETING SERIES: This is the Alamoroad (NV), Destazo(CA) and Driftfence (T NM)series. Alamoroad soils have 60 to 80 percent rock fragments in the particle-size control section. DeStazo soils have mean annual soil temperature of 15 to 18 degrees C. (59 to 64 degrees F.) and is always moist from 20 to 38 centimeters (8 to 15 inches) during late November until March.

GEOGRAPHIC SETTING: Pahrump soils are on lake terraces. Slope ranges from 0 to 15 percent. These soils formed in lacustrine deposits from lake bed and offshore bar sediments derived from limestone. Elevations are 730 to 960 meters (2,400 to 3,150 feet). The climate is arid with hot, dry summers and warm, occasionally moist winters. The mean annual precipitation is between 75 to 178 millimeters (3 and 7 inches); mean annual air temperature is between 17 to 18 degrees C. (62 and 65 degrees F.), and frost-free season is about 180 to 240 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arizo, Commski, Lastchance, Vegastorm, Wodavar and Yermo series. All soils have less than 18 percent clay in their control section. Arizo, Commski, Lastchance and Yermo soils do not have hard calcium carbonate concretions and nodules as rock fragments. Vegastorm soils have recent alluvium over lake sediments. Wodavar soils are shallow to a hardpan.

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

USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. Present vegetation includes creosotebush, white bursage, Fremont dalea and ephedra.

DISTRIBUTION AND EXTENT: Mojave Desert of southern Nevada; MLRA 30. The soils are not extensive.

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

SERIES ESTABLISHED: Nye County, Nevada, 1981. The name is from the nearby town of Pahrump, Nevada.

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

Ochric epipedon - 0 to 5 centimeters (0 to 2 inches) (A horizon).
Calcic horizon - 5 to 107 centimeters (2 to 42 inches) (Bk1, Bk2, 2Bk1, 2Bk2 and 2Bk3 horizons).
Petronodic feature - 41 to 107 centimeters (16 to 42 inches) (2Bk1, 2Bk2 and 2Bk3 horizons).
Particle-size control section - 25 to 100 centimeters (10 to 40 inches) (Part of the Bk2, 2Bk1, 2Bk2 and part of the 2Bk3 horizons).

Responsibility for this series was transferred from Davis to Phoenix 12/2015. The last revision to the series was 2/2011. ET

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National Cooperative Soil Survey
U.S.A.