LOCATION DECAN NV

Established Series
Rev. ELS-BKP
06/2016

DECAN SERIES

Decan series consists of moderately deep over an indurated duripan, well drained soils that formed in alluvium derived from welded tuff and mixed lacustrine deposits. Decan soils are on fan remnants. Slopes are 2 to 30 percent. The mean annual precipitation is about 275 mm and the mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Fine, smectitic, mesic Argiduridic Durixerolls

TYPICAL PEDON: Decan gravelly clay loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 5 cm; grayish brown (10YR 5/2) gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate thick platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine interstitial pores; 20 percent gravel; slightly acid (pH 6.2); abrupt smooth boundary.

A2--5 to 8 cm; dark grayish brown (10YR 4/2) gravelly clay loam, very dark grayish brown (10YR 3/2) moist; strong very fine granular structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine roots; many very fine interstitial and few very fine tubular pores; 20 percent gravel; slightly acid (pH 6.2); abrupt smooth boundary. (Combined thickness of A horizons is 8 to 18 cm thick)

Bt1--8 to 20 cm; brown (7.5YR 4/2) clay, dark brown (7.5YR 3/2) moist; moderate medium prismatic structure; hard, firm, moderately sticky and very plastic; common very fine and few fine and medium roots; common very fine tubular pores; many pressure faces on faces of peds and faint clay films lining pores; 10 percent gravel; slightly acid (pH 6.3); clear wavy boundary.

Bt2--20 to 43 cm; brown (7.5YR 4/4) clay, dark brown (7.5YR 3/4) moist; moderate medium prismatic structure; hard, firm, very sticky and very plastic; common very fine and few fine and medium roots; common very fine tubular pores; many pressure faces on faces of peds; 10 percent gravel; neutral (pH 6.6); abrupt wavy boundary. (Combined thickness of Bt horizons is 32 to 48 cm thick)

Btk--43 to 58 cm; pink (7.5YR 7/4) clay loam, brown (7.5YR 5/4) moist; weak medium prismatic structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine through medium roots; many very fine interstitial pores; few faint clay films on faces of peds and lining pores; many fine and medium prominent very pale brown (10YR 8/2) calcium carbonate masses on the bottom of rock fragments; 10 percent gravel; slightly alkaline (pH 7.6); abrupt wavy boundary. (13 to 20 cm thick)

Bqkm--58 to 88 cm; light brown (7.5YR 6/4) indurated duripan with 1 to 2 millimeter thick, continuous silica laminae at the top of the horizon and light brown (7.5YR 6/4) strongly cemented silica and calcium carbonate materials stratified with a weakly cemented sandy loam matrix; massive; extremely hard, extremely firm, brittle; common fine interstitial pores in weakly cemented material; strongly alkaline (pH 8.8). (25 to 40 cm thick)

TYPE LOCATION: Lincoln County, Nevada; about 1200 feet north of the southeast corner of section 6, T. 4 S., R. 71 E; USGS Uvada 7.5 minute topographic quadrangle; latitude 37 degrees 37 minutes 32.9 seconds N and longitude 114 degrees 4 minutes 50.9 seconds W; UTM zone 11s, 757622e, 4168306n; WGS84 Decimal Degrees 37.6252778 latitude, -114.0811111 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, but are moist in winter and spring and for 10 to 20 days cumulative between July through October due to summer convection storms; aridic bordering xeric moisture regime.
Mean annual soil temperature: 8 to 12 degrees C.
Mollic epipedon thickness: 18 to 40 cm.
Depth to secondary calcium carbonate: 40 to 65
Argillic horizon thickness: 38 to 70 cm. Depth to duripan: 50 to 100 cm.
Duripan thickness: 25 to 40 cm.
Calcium carbonate stage development: Stage IV.

Particle-size control section - Clay content: 35 to 45 percent.
Rock fragments: 0 to 15 percent mainly gravel.

A horizons
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3 dry and moist.
Reaction: Slightly acid or neutral.
Mineralogy: 15 to 24 percent volcanic glass in the 0.02 to 2.0 mm fraction and averages 0.05 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Other: Eroded phases are recognized with this series.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 through 4 dry and moist.
Clay content: 40 to 50 percent
Rock fragments: 10 to 15 percent with some pedons containing thin sub-horizons that average up to 35 percent rock fragments.
Mineralogy: 15 to 24 percent volcanic glass in the 0.02 to 2.0 mm fraction and averages 0.05 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Structure: Moderate or strong, medium or fine prismatic, subangular blocky, or angular blocky.
Consistence: Hard or very hard.
Reaction: Slightly acid or neutral.

Btk horizon and Bk horizon (when present)
Hue: 10YR or 7.5YR
Value: 6 through 8 dry, 5 or 6 moist.
Chroma: 4 or 5 dry and moist.
Texture: Clay loam and loam
Clay content: 25 to 35 percent
Structure: Prismatic or subangular blocky.
Rock fragments: 5 to 15 percent gravel.
Reaction: Slightly alkaline through strongly alkaline.
Secondary calcium carbonate concentrations: Common or many violently effervescent fine and medium calcium carbonate masses on the bottom of rock fragments.
Calcium carbonate equivalent: 10 to 20 percent in the fine earth fraction.
Other features: In some pedons there are sub-horizons where secondary calcium carbonate overwhelms the expression of clay in the profile which results in the field identification of Bk horizons.

Bqkm horizon
Hue: 10YR or 7.5YR
Value: 6 through 8 dry, 5 through 7 moist.
Chroma: 1 through 6 dry and moist.
Mineralogy: 15 to 24 percent volcanic glass in the 0.02 to 2.0 mm fraction and averages 0.05 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Structure: Very thick platy, thick platy, or massive.
Cementation: 1 to 10 mm thick continuously indurated silica and calcium carbonate laminae at the top of horizons in most pedons. Some pedons contain sub-horizons of continuous alternating thick plates of weakly through strongly cemented material.

2Bk and 2C horizons (when present)
Hue: 10YR or 7.5YR.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 3 or 4 dry and moist.
Rock fragments: 0 to 15 percent weathered welded tuff fragments.
Consistence: hard or very hard, slightly brittle or brittle.
Concentrations: 0 to 5 percent calcium carbonate seams within the matrix and 0 to 5 percent calcium carbonate masses concentrated in sub-horizons of some pedons.
Mineralogy: 10 to 20 percent volcanic glass in the 0.02 to 2.0 mm fraction and averages 0.01 to 0.05 percent Al plus 1/2Fe, extracted by ammonium oxalate.

COMPETING SERIES: These are the Adios, Barnard, Ollierivas, Uana and Xerta series.

Adios, Ollierivas and Xerta soils have a lithic contact at less than 100 cm. Barnard soils contain less than 5 percent coarse fragments in the particle-size control section and do not receive the 10 to 20 days of summer precipitation. Uana soils have a calcium carbonate equivalent of 20 to 40 percent in the Btk horizon and are 22 to 40 cm deep to secondary calcium carbonate.

GEOGRAPHIC SETTING: Decan soils are on fan remnants. These soils formed in alluvium derived from welded tuff and mixed lacustrine deposits. Elevations are 1,650 to 2,150 meters. Slopes are 2 to 30 percent. The climate is cool, semiarid. The mean annual precipitation is 250 to 300 mm, the mean annual temperature is 7 to 11 degrees C, and the frost-free season is 100 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Acoma, Cedaran, Uana and Wakansapa soils. Acoma soils have an ochric epipedon and a calcic horizon below an argillic horizon at 75 and 100 cm. Cedaran and Wakansapa soils are shallow to bedrock. Uana soils have a calcium carbonate equivalent of 20 to 40 percent in the Btk horizon and are 22 to 40 cm deep to secondary calcium carbonate.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained, slow or medium runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Livestock grazing and wildlife habitat. The potential native vegetation is Wyoming big sagebrush, Mountain big sagebrush, cliffrose, bottlebrush squirreltail, and Indian ricegrass. This pedon is correlated to ecological site Loamy 10-12 P.Z., R029XY029NV.

DISTRIBUTION AND EXTENT: East central Nevada. Decan soils are moderately extensive. MLRA 29 and 28A.

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

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

REMARKS: Decan was reclassified from frigid to mesic in 1990 to better represent the series concept. In 2009 the ecological site correlation was changed from a woodland potential to a rangeland potential based on soil properties.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 20 cm (A1, A2 and Bt1 horizons).
Argillic horizon - The zone from 8 to 58 cm (Bt1, Bt2, and Btk horizons).
Duripan - The zone from 58 to 88 cm (Bqkm horizon).
Particle-size control section - The zone from 8 to 58 cm (Bt1, Bt2 and Btk horizons).

ADDITIONAL DATA: Previous authors and editors include: DJM-RLB.

National Cooperative Soil Survey
U.S.A.