LOCATION ARMESPAN                NV

Established Series
Rev. EWB/WED/JVC
05/2016

ARMESPAN SERIES

The Armespan series consists of very deep, well drained soils that formed in alluvium derived from mixed rocks. Armespan soils are on fan remnants, inset fans, beach terraces, and ballenas. Slopes are 0 to 50 percent. The mean annual precipitation is about 250 mm and the mean annual temperature is about 11 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Durinodic Xeric Haplocalcids

TYPICAL PEDON: Armespan very gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 40 percent gravel.

A1--0 to 3 cm; light gray (10YR 7/2) very gravelly sandy loam, grayish brown (10YR 5/2) moist; moderate thin platy structure; slightly hard, very friable, slightly sticky and nonplastic; few very fine roots; few very fine interstitial and common very fine vesicular pores; 35 percent gravel; strongly effervescent; moderately alkaline (pH 8.3); clear smooth boundary.

A2--3 to 10 cm; light gray (10YR 7/2) sandy loam, grayish brown (10YR 5/2) moist; moderate thin and medium platy structure; slightly hard, very friable, slightly sticky and nonplastic; few very fine roots; few very fine interstitial and common very fine vesicular pores; 10 percent gravel; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (combined thickness of the A horizons is 5 to 18 cm).

Bw--10 to 23 cm; very pale brown (10YR 7/3) gravelly sandy loam, brown (10YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; few very fine and medium roots; many very fine interstitial pores; 15 percent gravel; violently effervescent; strongly alkaline (pH 8.5); gradual wavy boundary. (0 to 15 cm thick)

Bk--23 to 48 cm; very pale brown (10YR 8/2) gravelly sandy loam, pale brown (10YR 6/3) moist; massive; slightly hard, friable, nonsticky and nonplastic; few very fine through medium roots; common very fine interstitial pores; 30 percent gravel; secondary calcium carbonate throughout matrix and as coats on rock fragments; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (13 to 41 cm thick)

Bqk--48 to 79 cm; very pale brown (10YR 8/2) very gravelly sandy loam, pale brown (10YR 6/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine interstitial pores; 40 percent gravel; 25 percent durinodes; secondary calcium carbonate segregated in discontinuous cemented zones and as pendants on bottom of rock fragments; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (25 to 66 cm thick)

Ck--79 to 152 cm; light gray (10YR 7/2) very gravelly loamy coarse sand, brown (10YR 5/3) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many very fine and fine interstitial pores; 45 percent gravel; secondary calcium carbonate coats on bottom of rock fragments; violently effervescent; strongly alkaline (pH 9.0).

TYPE LOCATION: Mineral County, Nevada; about 40 miles east-southeast of Hawthorne; approximately 1,600 feet north and 1,500 feet west of the projected southeast corner of section 9, T. 7 N., R. 37 E.; USGS Bettles Well 7.5 minute topographic quadrangle; latitude 38 degrees 28 minutes 36.7 seconds N and longitude 117 degrees 53 minutes 3.4 seconds W; WGS84 Decimal Degrees 38.4770556 latitude, -117.884444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in winter and spring, dry in summer and fall except for 10 to 20 days cumulative 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 calcic horizon: 10 to 25 cm.
Calcic horizon thickness: 38 to 90 cm.
Reaction: Moderately alkaline or strongly alkaline.
Effervescence: Strongly effervescent or violently effervescent throughout.

Particle-size control section - Clay content: 10 to 18 percent;
Rock fragments: 35 to 60 percent, mainly gravel of mixed lithologies.

A horizons
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 through 4, dry or moist.
Calcium carbonate equivalent: 0 to 10 percent.

Bw horizon (when present)
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 through 4, dry or moist.
Texture: Gravelly sandy loam or gravelly loam.
Rock fragments: 15 to 35 percent, dominantly gravel.
Consistence: Soft or slightly hard dry, nonsticky or slightly sticky, nonplastic or slightly plastic wet.

Bk horizon
Value: 6 through 8 dry, 5 through 7 moist.
Chroma: 2 through 4, dry or moist.
Texture: Gravelly sandy loam or gravelly loam.
Rock fragments: 15 to 35 percent, mainly gravel.
Consistence: Soft or slightly hard dry, very friable or friable moist, nonsticky or slightly sticky and nonplastic or slightly plastic.
Structure: Massive, weak to moderate platy or subangular blocky.
Identifiable secondary carbonates: Carbonate throughout horizon matrix as coats and masses. Some pedons have few to many fine coats and pendants on underside of gravel.
Calcium carbonate equivalent: 10 to 35 percent.

Bqk horizon
Value 6 through 8 dry, 5 through 7 moist.
Chroma: 2 through 4, dry or moist.
Texture: Very gravelly sandy loam or very gravelly coarse sandy loam.
Rock fragments: 35 to 60 percent, mainly gravel.
Consistence: Loose to hard, dry; loose to firm, moist; nonsticky to slightly sticky and nonplastic to slightly plastic wet.
Secondary silica: 20 to 40 percent silica and carbonate-cemented durinodes. 20 to 50 percent weak to strong silica cementation in discontinuous zones.
Identifiable secondary carbonates: Common or many pendants on undersides of rock fragments. Some pedons have few fine or medium masses of calcium carbonate.
Calcium carbonate equivalent: 10 to 35 percent.

Ck horizonValue: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4, dry or moist.
Texture: Very gravelly loamy coarse sand or very gravelly loamy sand.
Rock fragments: 35 to 60 percent, mainly gravel.
Clay content: 5 to 10 percent.
Structure: Massive or single grain.
Consistence: Loose to hard, dry; loose to firm, moist.
Identifiable secondary carbonates: Common pendants on undersides of rock fragments. Some pedons have few fine masses.
Calcium carbonate equivalent: 10 to 35 percent.

COMPETING SERIES: These are the Automal, Dakent, Morbench, Pyrat, and Sugarcreek series.

Automal and Pyrat soils have mean annual soil temperature of 8 to 11 degrees C and are dry throughout the summer. Dakent soils have 60 to 75 percent rock fragments in the particle-size control section. Morbench soils have mean annual soil temperature of 9 to 11 degrees C and have calcic horizons that are 89 to 140 cm thick. Sugarcreek soils have bedrock at depths of 50 to 100 cm.

GEOGRAPHIC SETTING: Armespan soils are on fan remnants, inset fans, beach terraces, and ballenas. They formed in alluvium derived from mixed rocks. Slopes are 0 to 50 percent. Elevations range from 1,310 to 2,387 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 300 mm, the mean annual temperature is 10 to 12 degrees C, and the frost-free period is 90 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Whilphang and Wrango soils. Whilphang soils are loamy, shallow to paralithic contacts, and do not have calcic horizons. Wrango soils are sandy-skeletal and do not have calcic horizons.

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

USE AND VEGETATION: Armespan soils are used for livestock grazing and wildlife habitat. The potential native vegetation is mainly black sagebrush, Indian ricegrass, spiny menodora, galleta, shadscale, and Nevada ephedra.

DISTRIBUTION AND EXTENT: Western and central Nevada. These soils are extensive with about 274,000 acres of the series mapped to date. MLRAs 27, 28A, 28B, and 29.

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

SERIES ESTABLISHED: Esmeralda County, Nevada, 1984.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1, A2 and part of the Bw horizons).
Calcic horizon - The zone from 23 to 79 cm (Bk and Bqk horizons).
Duric feature - The zone from 48 to 79 cm (Bqk horizon).
Particle-size control section - The zone from 25 to 100 cm (Bqk, parts of the Bk and Ck horizons).

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National Cooperative Soil Survey
U.S.A.