LOCATION SEVAL                   NV

Established Series
Rev. RLB/GAM/BKP
06/2016

SEVAL SERIES

Seval series consists of moderately deep, well drained soils over an indurated silica and calcium carbonate cemented duripan. Seval soils formed in loess over alluvium derived from welded tuff and mixed lacustrine sediments. Seval soils are on the backslopes of eroded fan remnants. Slopes are 15 to 35 percent. The mean annual precipitation is 250 mm and the mean annual temperature is 9 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Argiduridic Durixerolls

TYPICAL PEDON: Seval very gravelly sandy loam - rangeland (Colors are for dry soil unless otherwise noted.)

A--0 to 8 cm; grayish brown (10YR 5/2) very gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few fine and very fine roots; many very fine and few fine interstitial, and few very fine tubular pores; 35 percent gravel and 20 percent cobbles; neutral (pH 7.0); clear wavy boundary. (5 to 10 cm thick)

Bt1--8 to 15 cm; brown (7.5YR 5/2) gravelly sandy clay loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure; slightly hard, friable, moderately sticky and very plastic; common fine and very fine, and few medium roots; few very fine tubular, and many very fine interstitial pores; few distinct clay films in pores and as bridges between sand grains; 20 percent gravel and 10 percent cobbles; neutral (pH 7.0); clear wavy boundary.

Bt2--15 to 36 cm; light brown (7.5YR 6/4) gravelly clay, brown (7.5YR 4/4) moist; weak medium prismatic structure; very hard, firm, very sticky and very plastic; few fine and very fine roots; few very fine and fine tubular, and many very fine and fine interstitial pores; many thin clay films in pores; few distinct clay films on the faces of peds and few distinct clay bridges between sand grains; 20 percent gravel and 10 percent cobbles; neutral (pH 7.0); clear wavy boundary. (Combined thickness of Bt horizons is 26 to 38 cm thick)

Btqk--36 to 58 cm; light brown (7.5YR 6/4) gravelly sandy loam, brown (7.5YR 4/4) moist; massive; hard, firm and brittle; few very fine tubular, and many very fine and fine interstitial pores; common faint clay films and few distinct clay films coating gravel and as bridges between sand grains; common fine distinct very pale brown soft calcium carbonate masses in the matrix; 30 percent gravel; moderately alkaline (pH 8.4); abrupt wavy boundary. (20 to 30 cm thick)

Bqkm--58 to 69 cm; white (10YR 8/1) alternating bands of strongly to indurated duripan with a 1 mm light gray (10YR 7/2) continuous silica cemented cap and 1 to 2 mm discontinuous horizontal and oblique silica laminae; massive; extremely hard or very rigid, slightly rigid or very rigid, brittle; abrupt wavy boundary. (8 to 13 cm thick)

2Bqkm--69 to 152 cm; pinkish gray (7.5YR 7/2) weakly cemented very gravelly material composed of stratified layers of fine sand, loamy sand, and loam, brown (7.5YR 5/2) moist; massive; hard, very firm, brittle; many fine and very fine interstitial pores; many silica and calcium carbonate bridges between sand grains; 35 percent gravel and 10 percent cobbles; moderately alkaline (pH 8.0).

TYPE LOCATION: Lincoln County, Nevada; about 1,820 feet south and 2,650 feet west of the of the northeast corner of sec. 9, T. l N ., R. 69 E.; USGS Rose Valley 7.5 minute topographic quadrangle; latitude 37 degrees 57 minutes 15.8 seconds N and longitude 114 degrees 15 minutes 42.5 seconds W; WGS84 Decimal Degrees 37.9543889 latitude, -115.2618056 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in summer and fall except intermittently moist for 10 to 20 days between July and September due to convection storms. Aridic soil moisture regime that borders on xeric.
Soil temperature: 8 to 11 degrees C.
Depth to duripan: 50 to 100 cm.
Mollic epipedon: 18 to 25 cm. In some pedons, when the upper 18 cm is mixed, it has a value darker than 6 dry and 4 moist.
Calcium carbonate stage development - IV

Particle-size control section - Clay content: Averages 27 to 35 percent.
Rock fragments: Averages 15 to 35 percent.

A horizon
Hue: 10YR or 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist.
Mineralogy: 15 to 24 percent volcanic glass in the parent material and averages 0.05 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 4 through 6 dry.
Chroma: 2 through 4 dry and moist.
Clay content: 27 to 45 percent.
Rock fragments: 15 to 35 percent, some pedons contain sub-horizons that average 35 to 55 percent.
Texture: Sandy clay loam, clay loam, sandy clay, or clay.
Mineralogy: 15 to 24 percent volcanic glass in the parent material and averages 0.05 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Structure: Prismatic or subangular blocky structure.
Concentrations: Some pedons contain thin sub-horizons with 5 to 20 percent secondary calcium carbonate concretions on the bottom of rock fragments.
Reaction: Neutral through moderately alkaline.

Btqk horizon
Hue: 10YR or 7.5YR.
Value: 4 through 7, dry.
Chroma: 3 or 4, moist.
Clay content: 18 to 27 percent.
Rock fragments: 15 to 35 percent, some pedons contain thin sub-horizons that average 35 to 55 percent.
Mineralogy: 15 to 24 percent volcanic glass in the parent material and averages 0.05 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Texture: Sandy loam, sandy clay loam, loam, or clay loam.
Cementation: Non-cemented to weakly cemented by secondary silica and calcium carbonate.
Secondary calcium carbonate: 10 to 30 percent concretions on the bottom of rock fragments.
Reaction: Moderately alkaline through strongly alkaline.

Bqkm horizon
Hue: 10YR or 7.5YR.
Value: 7 to 8, dry.
Chroma: 2 or 3, dry or moist.
Cementation: Indurated through strongly cemented with some pedons containing thin sub-horizons that are moderately cemented.
Structure: Very coarse platy structure or massive.
Consistence: Extremely hard through very rigid, slightly rigid through very rigid.
Duripan features: variegated brown (10YR 4/3), light yellowish brown (10YR 6/4), and white (10YR 8/1) in sub-horizons of some duripans.

2Bqkm horizon
Hue: 10YR or 7.5YR.
Value: 5 to 7 dry.
Chroma: 2 or 3 dry or moist.
Clay content: 2 to 18 percent.
Rock fragments: 35 to 60 percent, some pedons contain thin sub-horizons that average 15 to 35 percent rock fragments.
Cementation: Moderate to strongly cemented.
Secondary calcium carbonate: 5 to 20 percent masses as dendritic threads or as concretions around rock fragments.
Reaction: Moderately alkaline through very strongly alkaline.
Mineralogy: 10 to 24 percent volcanic glass in the parent material and averages 0.01 to 0.05 percent Al plus 1/2Fe, extracted by ammonium oxalate.

COMPETING SERIES: These are the Deerhorn, Schnipper, and Selah series.

Deerhorn soils have bedrock below the duripan. Schnipper soils average less than 15 percent rock fragments in the particle-size control section. Selah soils are not intermittently moist for 10 to 20 days between July and September due to convection storms.

GEOGRAPHIC SETTING: Seval soils are on backslopes of eroded fan remnants at elevations of 1,700 to 1,850 meters. Slope range from 15 to 35 percent. Seval soils formed in loess over alluvium derived from welded tuff and reworked lacustrine deposits. The climate is cool, semiarid with a mean annual temperature of 7 to 10 degrees C. The mean annual precipitation is 200 to 300 mm. The frost free season is 90 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Heist, Minu, and Roval soils. Heist soils are very deep and do not have a duripan. Minu and Roval soils have an Ochric epipedon and are shallow to a duripan. Roval soils average less than 27 percent clay in the particle-size control section.

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

USE AND VEGETATION: Seval soils are used primarily for wildlife habitat. The principal native vegetation is black sagebrush, Indian ricegrass, squirreltail, Sandberg's bluegrass, and a minor component of Utah juniper and Singleleaf pinyon. This pedon has been correlated to Ecological Site Description R029XY014NV, Shallow Calcareous Slope 8-12 P.Z.

DISTRIBUTION AND EXTENT: East-central Nevada. Seval soils are not extensive (2,400 acres). MLRA 29.

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

SERIES ESTABLISHED: Lincoln County (Meadow Valley Area), Nevada, 1971.

REMARKS: Seval soils were formerly classified as fine, montmorillonitic but as a result of additional mapping and laboratory data, they were changed in 1990 to fine-loamy, to better reflect the concept of the series.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the surface to 15 cm (A and Bt1 horizon).
Argillic horizon - The zone from 8 to 58 cm (Bt1 and Bt2 Horizon).
Duripan - The zone from 58 to 69 cm (Bqkm horizon).
Particle-size control section - The zone from 8 to 58 cm (Bt1, Bt2, and Btqk horizons).

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National Cooperative Soil Survey
U.S.A.