LOCATION ALKO                    NV+AZ CA

Established Series
Rev. LNL/LR/RLB
04/2015

ALKO SERIES

The Alko series consists of shallow or very shallow over a duripan, well drained soils that formed in mixed alluvium from ignimbrite, granodiorite and basalt. Alko soils are on fan piedmonts and have slopes that range from 0 to 15 percent. The mean annual precipitation is about 6 inches and the mean annual air temperature is about 65 degrees F.

TAXONOMIC CLASS: Loamy, mixed, superactive, thermic, shallow Typic Haplodurids

TYPICAL PEDON: Alko loamy coarse sand rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 1 inch; light brownish gray (10YR 6/2) loamy coarse sand, dark grayish brown (10YR 4/2) moist; single grained; loose; many very fine and fine interstitial pores; strongly effervescent; strongly alkaline (pH 8.6); abrupt smooth boundary. (0 to 1 inches thick)

A2--1 to 4 inches; light gray (10YR 7/2) coarse sandy loam, dark grayish brown (10YR 4/2) moist; moderate medium and coarse platy structure; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine, fine and medium vesicular pores; violently effervescent; strongly alkaline (pH 8.8); abrupt smooth boundary. (3 to 5 inches thick)

Bk--4 to 11 inches; very pale brown (10YR 7/3) coarse sandy loam, brown (10YR 4/3) moist, brown (10YR 5/3) when moist and rubbed; weak medium and fine granular structure; soft, very friable nonsticky and non plastic, many very fine roots; many very fine and fine interstitial pores; violently effervescent; strongly alkaline (pH 8.8) abrupt wavy boundary. (6 to 15 inches thick)

Bqkm1--11 to 19 inches; white (10YR 8/1) indurated silica and lime cemented duripan, light gray (10YR 7/2) moist; weak and moderate thin plates; extremely hard, extremely firm; few very fine, fine and medium roots between plates; violently effervescent; strongly alkaline (pH 8.8); abrupt wavy boundary. (7 to 10 inches thick)

Bqkm2--19 to 33 inches; white (10YR 8/1) indurated silica and lime cemented duripan, very pale brown (10YR 7/3) moist; massive; extremely hard, extremely firm; few very fine and fine roots; few very fine interstitial pores; violently effervescent; very strongly alkaline (pH 9.2); abrupt smooth boundary. (5 to 15 inches thick)

2Bk--33 to 43 inches; light gray (10YR 7/2) coarse sand, dark grayish brown (10YR 4/2) moist; massive; slightly hard, very friable; nonsticky and nonplastic, few very fine and fine roots; many very fine and fine interstitial pores; discontinuous weak lime cementation; violently effervescent; very strongly alkaline (pH 9.2); abrupt wavy boundary. (7 to 27 inches thick)

3C --43 to 60 inches; light brownish gray (10YR 6/2) coarse sand, dark grayish brown (10YR 4/2) moist; single grained; nonsticky and nonplastic, few very fine roots; many very fine and fine interstitial pores; noneffervescent; strongly alkaline (pH 8.9).

TYPE LOCATION: Lincoln County, Nevada; along a dirt road to Alamo Airport, approximately 2.22 miles west of Alamo High School, 0.72 mile west of the airport and 60 feet south of road; in an unsurveyed township about 500 feet south and 5,000 feet west of the NW corner of section 7, T.39 S., R.61 E.

RANGE IN CHARACTERISTICS:

Soil moisture - Usually dry. Moist in some part of the moisture control section for 10 to 20 days cumulative during the period July through October.

Soil temperature - 59 to 66 degrees F.

Depth to duripan: 5 to 20 inches.

Reaction: Moderately alkaline or strongly alkaline above the duripan, strongly alkaline or very strongly alkaline below the duripan.

Other features: Some pedons are slightly influence from gypsum.


Control section - Clay content: 8 to 18 percent

Rock fragments: 0 to 35 percent.


A horizon - Hue: 10YR or 7.5YR.

Value: 6 through 8 dry, 4 through 7 moist, commonly 1 unit of value darker than underlying Bk or Bw horizon.

Chroma: 2 through 4.

Effervescence: Strongly effervescent or violently effervescent.


Bk and Bw horizon (when present)- Hue: 10YR or 7.5YR.

Value: 6 through 8 dry, 4 through 7 moist.

Chroma: 2 through 4.

Texture: Dominantly sandy loam or coarse sandy loam, some pedons contain thin strata of loam or other textures.

Structure: Massive or granular.

Secondary lime accumulation: Some pedons have common thin lime coats on undersides of rock fragments.

Effervescence: Strongly effervescent or violently effervescent,


Bqkm horizon - Rupture resistance: Very strongly cemented to indurated.


2Bk and 3C horizon - Hue: 10YR or 7.5YR.

Value: 6 through 8 dry, 4 through 7 moist

Chroma: 2 through 4.

Textures: Below the pan are sand, coarse sand or loamy fine sand.

Structure: Massive, subangular blocky or single grain.

Secondary lime accumulation: Some pedons have common thin lime coats on undersides of rock fragments.

Effervescence: Strongly effervescent or violently effervescent, less than 2 percent exchangeable sodium in the lower part of the Bk horizon.

COMPETING SERIES: These are the Muroc(CA), Nebona(CA), Stewart(AZ), and Zalda(NV) series. Muroc and Zalda soils have bedrock within 40 inches. Nebona and Stewart soils have a SAR or more than 13.

GEOGRAPHIC SETTING: Alko soils are on fan piedmonts and relict alluvial flats. These soils formed in mixed alluvium derived commonly from ignimbrite, granodiorite and basalt, but components from quartzite, limestone, dolomite and shale are included in some areas. Slopes are 0 to 15 percent. Elevations are 2400 to 5500 feet. The climate is hot and arid. The mean annual precipitation is 3 to 10 inches; mean annual temperature is 58 to 67 degrees F., and the frost-free season is 175 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Pintwater, Theriot and Tickapoo soils. Pintwater and Theriot soils are loamy-skeletal. Tickapoo soils have fine textured argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderately rapid permeability above the duripan.

USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly creosotebush, shadscale, and some spiny hopsage, yucca, cacti, Joshua trees and Fremont dalea.

DISTRIBUTION AND EXTENT: The soils are mapped in southeastern Nevada, Northern Arizona, and Mojave Desert, California. The series is moderately extensive. MLRA 30.

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

SERIES ESTABLISHED: Kern County, California, 1976.

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

Duripan - The zone from about 11 to 13 inches (Bqkm1 and Bqkm2 horizons).

Particle-size control section - The zone from the surface to about 11 inches (A1, A2 and Bk horizons).

ADDITIONAL DATA: NSSL pedon S59NV-009-032 (type location) and S59NV-009-033. Published in Soil Survey Investigations Report #23.

Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 5/1997. ET

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National Cooperative Soil Survey
U.S.A.