LOCATION HARDNUT                 CA+NV

Established Series
Rev. EWB-JVC-JBF
03/2017

HARDNUT SERIES

The Hardnut series consists of shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks with surficial additions of eolian volcanic ash. Hardnut soils are on mountains. Slopes are 15 to 75 percent. The mean annual precipitation is about 360 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Aridic Lithic Argixerolls

TYPICAL PEDON: Hardnut very gravelly ashy sandy loam--forestland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 50 percent gravel, 20 percent cobbles, and 5 percent stones.

A--0 to 8 cm; grayish brown (10YR 5/2) very gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine interstitial pores; 50 percent gravel and 5 percent cobbles; neutral (pH 6.8); clear smooth boundary. (3 to 10 cm thick)

Bt1--8 to 20 cm; grayish brown (10YR 5/2) extremely gravelly ashy sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; many very fine, fine, and medium roots; common very fine tubular and interstitial pores; common faint clay films coating sand grains; 65 percent gravel; neutral (pH 6.8); clear wavy boundary. (10 to 20 cm thick)

Bt2--20 to 38 cm; brown (10YR 5/3) extremely gravelly ashy clay loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine, fine, medium, and coarse roots; common very fine tubular and interstitial pores; common distinct clay films on faces of peds and lining pores; 75 percent gravel; neutral (pH 6.9); abrupt irregular boundary. (15 to 25 cm thick)

R--38 cm; hard fractured andesite.

TYPE LOCATION: Mono County, California; on the Toiyabe National Forest about 1.2 miles east of Murphy Pond; about 1,700 feet south and 1,000 feet west of the northeast corner of section 13, T. 6 N., R. 25 E.; USGS Bridgeport 7.5 minute topographic quadrangle; latitude 38 degrees 22 minutes 11.8 seconds N and longitude 119 degrees 10 minutes 34.7 seconds W; WGS84 Decimal Degrees 38.3699444 latitude, -119.1763056 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry from July through October; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 25 to 40 cm; includes the Bt1 horizon and also includes the Bt2 horizon in some pedons.
Depth to bedrock: 36 to 50 cm to a lithic contact.

Particle-size control section - Clay content: Averages 20 to 30 percent.
Rock fragments: Averages 60 to 80 percent, mainly gravel. Lithology of fragments is andesite or tuff; Volcanic glass content: : Averages 30 percent or more in coarse silt through very coarse sand fractions.

A horizon
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 2 to 4 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 20 to 60 percent in the coarse silt through fine sand fractions.
Oxalate aluminum plus one-half oxalate iron: 0.2 to 0.4 percent.

Bt1 horizon
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly ashy sandy clay loam or extremely gravelly ashy loam.
Clay content: 18 to 25 percent.
Rock fragments: 60 to 80 percent.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 20 to 50 percent in the coarse silt through fine sand fractions.
Oxalate aluminum plus one-half oxalate iron: 0.2 to 0.4 percent.

Bt2 horizon
Hue: 10YR or 7.5YR.
Value: 4, 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly ashy sandy clay loam or extremely gravelly ashy clay loam.
Clay content: 25 to 35 percent.
Rock fragments: 60 to 80 percent.
Organic matter content: 0.5 to 2 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 15 to 40 percent in the coarse silt through fine sand fractions.
Oxalate aluminum plus one-half oxalate iron: 0.2 to 0.4 percent.

COMPETING SERIES: These are the Badrock, Domehill, Farepeak, Hardepth, and Schoolmarm series.

Badrock, Domehill and Hardepth soils have lithic contacts within 18 to 36 cm of the soil surface. Schoolmarm soils are intermittently moist for 10 to 20 days cumulative from July through September due to convection storms. Farepeak soils have lithic contacts within 25 to 36 cm of the soil surface and are intermittently moist for 10 to 20 days cumulative from July through September due to convection storms.

GEOGRAPHIC SETTING: Hardnut soils are on mountains. They typically occur on backslope positions. They formed in residuum and colluvium derived from volcanic rocks such as andesite or tuff with surficial additions of eolian volcanic ash. The probable sources of the volcanic ash are the Mono Craters and Long Valley Caldera in eastern California. Slopes are 15 to 75 percent. Elevations range from 1,980 to 2,565 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 400 mm, the mean annual temperature is 6 to 7 degrees C., and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Domehill soil and the Epvip soil. Epvip soils are shallow to paralithic contacts and have a xeric moisture regime.

DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderately slow permeability; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Hardnut soils are used for forestland, recreation, watershed, and wildlife habitat. The native vegetation is mainly a forest canopy of singleleaf pinyon with an understory of mountain big sagebrush, antelope bitterbrush, and Thurber's needlegrass.

DISTRIBUTION AND EXTENT: Eastern California and western Nevada, in the western part of the Great Basin. These soils are moderately extensive. MLRA 26.

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

SERIES ESTABLISHED: Mineral County Area, Nevada, 2005. The series was proposed in Mono County (Toiyabe National Forest Area), California, 2004.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 38 cm (A, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 8 to 38 cm (Bt1 and Bt2 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 38 cm (A, Bt1, and Bt2 horizons).
Lithic contact - The boundary at 38 cm to underlying hard bedrock (R layer).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from 8 to 28 cm (Bt1 and Bt2 horizons).

Classification was updated to 11th edition on 07/2011 changed from Lithic Argixerolls to Aridic Lithic Argixerolls.

ADDITIONAL DATA: User Pedon ID: 2015CA051004.

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National Cooperative Soil Survey
U.S.A.