LOCATION AHCHEW                  NV

Established Series
Rev. EWB-IR-WED-JVC
02/2017

AHCHEW SERIES

The Ahchew series consists of shallow, well drained soils that formed in residuum and colluvium derived from altered volcanic rocks with eolian additions of volcanic ash. Ahchew soils are on mountains. Slopes are 30 to 75 percent. The mean annual precipitation is about 330 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic, shallow Vitrixerandic Haplargids

TYPICAL PEDON: Ahchew very gravelly ashy fine sandy loam--forestland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 3 percent stones, 5 percent cobbles, and 45 percent gravel.

A1--0 to 5 cm; light brownish gray (10YR 6/2) very gravelly ashy fine sandy loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common very fine interstitial pores; 5 percent stones and 35 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (5 to 10 cm thick)

A2--5 to 18 cm; light brownish gray (10YR 6/2) very gravelly ashy fine sandy loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and few fine roots; common very fine tubular pores; 5 percent stones, 35 percent gravel; common 10 to 30 mm diameter pockets of white (10YR 8/1) volcanic ash; neutral (pH 7.0); clear wavy boundary. (13 to 23 cm thick)

Bt1--18 to 30 cm; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 4/3) moist; strong medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine, few fine, and few medium roots; common very fine tubular pores; common distinct clay films on faces of peds; 45 percent gravel; few fine seams of volcanic ash; neutral (pH 6.8); gradual wavy boundary (13 to 18 cm thick)

Bt2--30 to 43 cm; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine through coarse roots; common very fine tubular pores; common distinct clay films on faces of peds; 55 percent gravel; few fine seams of volcanic ash; neutral (pH 6.6); gradual wavy boundary. (0 to 13 cm thick)

Cr--43 to 56 cm; weathered altered volcanic rock.

TYPE LOCATION: Mineral County, Nevada; on the Hawthorne Army Ammunition Plant in the Wassuk Range; approximately 1,700 feet south and 2,400 feet east of the northwest corner of section 27, T. 9 N., R. 28 E.; USGS Mount Grant 7.5 minute topographic quadrangle; latitude 38 degrees 36 minutes 49 seconds N and longitude 118 degrees 50 minutes 32 seconds W; WGS84 Decimal Degrees 38.6137222 latitude, -118.8422222 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in summer and fall except for 10 to 20 cumulative days between July and October due to convection storms; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 12 to 14 degrees C.
Depth to bedrock: 36 to 50 cm to a paralithic contact. The paralithic materials below the contact are weathered, altered volcanic rock such as andesitic or tuff.

Particle-size control section - Clay content: 27 to 35 percent.
Rock fragments: 35 to 60 percent, mainly gravel. Lithology of fragments is volcanic rocks such as andesite or tuff.

A horizons
Value: 6 or 7 dry.
Chroma: 2 or 3, dry or moist.
Clay content: 10 to 18 percent.
Structure: Subangular blocky or platy.
Reaction: Slightly acid or neutral
Volcanic glass content: 30 to 60 percent in coarse silt through very coarse sand fractions.

Bt horizons
Value: 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Clay content: 27 to 35 percent
Rock fragments: 35 to 60 percent.
Structure: Subangular blocky or is massive.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Ahchew soils are on mountains. They typically occur on backslope positions. These soils formed in residuum and colluvium from altered volcanic rock with eolian additions of volcanic ash. Slopes are 30 to 75 percent. Elevations range from 1,650 to 2,730 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 360 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Wassit soils. Wassit soils are shallow to lithic contacts.

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

USE AND VEGETATION: Ahchew soils are used for watershed, woodland products, and wildlife habitat. The present vegetation is mainly a forest canopy of singleleaf pinyon with an understory of mountain big sagebrush, Sandberg's bluegrass, Thurber's needlegrass, and antelope bitterbrush.

DISTRIBUTION AND EXTENT: Western Nevada. These soils are not extensive with about 5,600 acres of the series mapped to date. MLRA 26.

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

SERIES ESTABLISHED: Mineral County (Hawthorne Army Ammunition Plant), Nevada, 1991.

REMARKS: The revision of February 2004 updates the taxonomic class from Loamy-skeletal, mixed, superactive, mesic, shallow Xeric Haplargids.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1 and A2 horizons)
Vitrandic intergrade feature - The zone from the soil surface to 18 cm (A1 and A2 horizons).
Argillic horizon - The zone from 18 to 43 cm (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 43 cm to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 18 to 43 cm (Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.