LOCATION HARDHAT                 NV

Established Series
Rev. DWW-RLB-JVC
10/2016

HARDHAT SERIES

The Hardhat series consists of very deep, well drained soils that formed in alluvium derived from mixed rocks and volcanic ash over lacustrine deposits. Hardhat soils are on fan skirts, inset fans, and lake terraces. Slopes are 0 to 8 percent. The mean annual precipitation is about 150 mm and the mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Durinodic Haplocalcids

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

A1--0 to 5 cm; light brownish gray (2.5Y 6/2) ashy silt loam, dark grayish brown (10YR 4/2) moist; strong thick platy structure parting to strong very thin platy; hard, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine vesicular pores; violently effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (3 to 10 cm thick)

A2--5 to 13 cm; light gray (10YR 7/2) ashy silt loam, brown (10YR 4/3) moist; moderate coarse prismatic structure parting to strong very thin platy; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine interstitial and few very fine vesicular pores; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (5 to 20 cm thick)

Bqk--13 to 25 cm; very pale brown (10YR 7/3) ashy silt loam, brown (10YR 5/3) moist; weak coarse prismatic structure parting to moderate thin platy; hard, friable, slightly sticky and slightly plastic; common very fine, fine, and few medium horizontal exped roots; common very fine tubular pores; few silica bridges between mineral grains and as coats on faces of peds; secondary carbonates segregated as few fine filaments; violently effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (8 to 38 cm thick)

Bk--25 to 43 cm; very pale brown (10YR 7/3) silt loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common very fine tubular pores; secondary carbonates are finely segregated in the matrix; violently effervescent; strongly alkaline (pH 8.8); abrupt smooth boundary. (0 to 25 cm thick)

2B'qk--43 to 58 cm; light gray (10YR 7/2) loam, brown (10YR 5/3) moist; strong thin and medium platy structure; very hard, firm and brittle, slightly sticky and slightly plastic; common very fine horizontal exped roots; many very fine vesicular pores; secondary carbonates segregated as many fine coats on faces of peds and lining some pores; violently effervescent; very strongly alkaline (pH 9.4); abrupt wavy boundary. (0 to 30 cm thick)

3Bqky1--58 to 81 cm; light gray (10YR 7/2) stratified lenses of paragravelly sandy loam and gravelly sand, brown (10YR 5/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine, fine and medium roots; common very fine tubular pores; 30 percent gravel; 20 percent hard, firm 5 to 15 mm durinodes; few fine gypsum filaments; secondary carbonates segregated as thin (0.5 mm) coats on bottoms of gravel; violently effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (13 to 38 cm thick)

3Bqky2--81 to 142 cm; pale yellow (5Y 8/2) paragravelly very fine sandy loam, olive (5Y 5/3) moist; moderate very thin platy structure; hard, firm and brittle, nonsticky and nonplastic; few very fine roots; common very fine interstitial pores; common fine prominent yellowish brown (10YR 5/6) and brown (10YR 4/3) moist, relict masses of iron accumulation; 30 percent very hard, very firm durinodes in matrix; few fine gypsum filaments; violently effervescent; strongly alkaline (pH 8.6); gradual wavy boundary. (0 to 76 cm thick)

3Bqky3--142 to 152 cm; light gray (2.5Y 7/2) very gravelly sandy loam, grayish brown (2.5Y 5/2) moist; strong thin platy structure; hard, firm and brittle, nonsticky and nonplastic; few very fine interstitial pores; 40 percent gravel; few fine gypsum filaments; many fine relict manganese coats on faces of peds; violently effervescent; moderately alkaline (pH 8.0)

TYPE LOCATION: Elko County, Nevada; about 10 miles south of Montello in Pilot Creek Valley; approximately 50 feet south and 25 feet west of the northeast corner of section 3, T. 37 N., R. 69 E.; USGS Pilot Peak SW 7.5 minute topographic quadrangle; latitude 41 degrees 7 minutes 28.7 seconds N and longitude 114 degrees 8 minutes 30.1 seconds W; WGS84 Decimal Degrees 41.1247222 latitude, -114.1408333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist for short periods in the winter and spring, dry late May through early November; typic aridic soil moisture regime.
Mean annual soil temperature: 12 to 14 degrees C.
Depth to secondary carbonates and silica: 10 to 25 cm.
Depth to horizons with a firm, brittle matrix: 25 to 50 cm.
Depth to gypsum: 30 to 64 cm.
Depth to lacustrine deposits: 38 to 64 cm.
Other features: C horizons are below 60 cm in some pedons.

Particle-size control section - Clay content: 8 to 18 percent.
Rock fragments: Average 5 to 20 percent, mainly gravel.

A horizons
Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4, dry or moist.
Reaction: Moderately alkaline or strongly alkaline.

Bqk and Bk horizons
Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 3 or 4, dry or moist.
Texture: Silt loam or very fine sandy loam, gravelly sandy loam, gravelly fine sandy loam and fine sandy loam in the upper subhorizons and stratified very fine sandy loam to gravelly sand in the lower subhorizons. Some pedons have texture of ashy silt loam or ashy very fine sandy loam in the Bqk horizon.
Structure: Weak prismatic, weak to strong platy, or it is massive.
Consistence: Hard or very hard.
Reaction: Moderately alkaline or strongly alkaline.
Secondary silica: The upper part has few to many silica bridges or coats, but the matrix is friable or very friable. Some subhorizons are continuously brittle and have firm or very firm consistence when moist.
Calcium carbonate equivalent: 10 to 20 percent.

Bqky horizons
Hue: 10YR through 5Y.
Value: 6 through 8 dry, 4 through 7 moist.
Chroma: 2 through 4, dry or moist.
Texture: Stratified paragravelly very fine sandy loam to very gravelly sandy loam.
Structure: Platy or it is massive.
Consistence: Soft to hard, very friable to firm, nonsticky or slightly sticky, nonplastic or slightly plastic.
Durinodes and secondary silica: Some subhorizon has a firm brittle matrix and also have 20 to 30 percent hard and firm 5 to 15 mm durinodes.
Reaction: Moderately alkaline through very strongly alkaline.
Gypsum crystals: Few or common.
Sodicity (SAR): 13 to 30.
Calcium carbonate equivalent: 10 to 20 percent.
Redoximorphic features: Relict masses of iron or manganese accumulation are common in any subhorizon.

COMPETING SERIES: These are the Caphor and Outerkirk series.

Caphor soils do not have horizons with gypsum, do not have ashy textures in the upper part of the profile, and have sandy textured 2Ck horizons with 100 cm of the soil surface. Outerkirk soils do not have horizons with gypsum, do not have ashy textures in the upper part of the profile, and have 5 to 8 percent calcium carbonate equivalent in the calcic horizon.

GEOGRAPHIC SETTING: Hardhat soils are on fan skirts, inset fans, and lake terraces. These soils formed in alluvium derived from mixed rocks and volcanic ash over lacustrine deposits. Slopes are 0 to 8 percent. Elevations range from 1,190 to 1,830 meters. The climate is arid with cool, moist winters and warm, dry summers. The mean annual precipitation is 125 to 200 mm, the mean annual temperature is 8 to 11 degrees C, and the frost-free period is 100 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jericho, Shuttle, and Wiffo soils. Jericho soils are loamy-skeletal and are shallow to indurated duripans. Shuttle soils have duripans at depths of 100 to 150 cm. Wiffo soils are loamy-skeletal and do not have durinodes or horizons with secondary silica.

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

USE AND VEGETATION: Hardhat soils are used for livestock grazing and wildlife habitat. The present vegetation is mainly shadscale and bottlebrush squirreltail.

DISTRIBUTION AND EXTENT: Eastern and central Nevada. These soils are moderately extensive. The original series concept is in MLRA 28A, while other acreage occurs in MLRAs 28B and 29.

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

SERIES ESTABLISHED: Elko County, Nevada, Northeast Part, 1986.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1, A2 part of Bk horizons).
Calcic horizon - The zone from 43 to 142 cm (2B'qk, 3Bqky1 and 3Bqky2 horizons).
Duric feature and durinodes - The zone from 43 to 152 cm (2B'qk, 2Bqky1, 3Bqky2, and 3Bqky3 horizons).
Particle-size control section - The zone from 25 to 100 cm (Bk, 2B'qk, 3Bqky1 and part of the 3Bqk2 horizons).

The taxonomic class was revised from Coarse-loamy, mixed, calcareous, mesic Haploduridic Torriorthents in April 2001. The revision of September 2002 updated the official series concept to reflect the presence of a calcic horizon as supported by laboratory data of the typical pedon.

ADDITIONAL DATA: The typical pedon at the series type location has full characterization by the Soil Survey Laboratory (SSL), Lincoln, NE, as user pedon ID 84NV007119 (pedon # 84P0619).

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National Cooperative Soil Survey
U.S.A.