LOCATION SKULLWAK NV+CA

Established Series
Rev. CEJ/TM/JVC/JBF
07/2016

SKULLWAK SERIES

The Skullwak series consists of very deep, poorly drained soils that formed in lacustrine deposits derived from mixed rocks. Skullwak soils are on lake plains. Slopes are 0 to 2 percent. The mean annual precipitation is about 180 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Fine, smectitic, calcareous, mesic Duric Halaquepts

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

A--0 to 5 cm; light gray (10YR 7/2) silt loam, pale brown (10YR 6/3) moist; moderate medium platy structure; hard, friable, moderately sticky and moderately plastic; few very fine roots; common very fine vesicular pores; strongly effervescent; very strongly alkaline (pH 9.4); abrupt smooth boundary. (3 to 13 cm thick)

C--5 to 25 cm; light gray (10YR 7/2) silty clay loam, yellowish brown (10YR 5/4) moist; moderate fine angular blocky structure; hard, friable, very sticky and very plastic; common very fine and fine roots; common very fine tubular and interstitial pores; strongly effervescent; very strongly alkaline (pH 9.2); clear smooth boundary. (15 to 28 cm thick)

2Bqk--25 to 43 cm; light gray (10YR 7/2) silty clay loam, yellowish brown (10YR 5/4) moist; moderate fine angular blocky structure; hard, friable, very sticky and very plastic; common very fine, common fine, and common medium roots; common very fine interstitial pores; many medium distinct light brownish gray (2.5Y 6/2) and light gray (2.5Y 7/2) moist zones of iron depletion; 15 percent 15 to 25 mm strongly cemented durinodes; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (0 to 18 cm thick)

3Bqkg1--43 to 76 cm; pale yellow (5Y 8/2) silty clay, light olive gray (5Y 6/2) moist; massive; very hard, very firm, very sticky and very plastic; common very fine and fine roots; few very fine tubular pores; many medium faint light gray (5Y 7/2) moist zones of iron depletion and many medium prominent yellowish brown (10YR 5/4) moist masses of iron accumulation; 75 percent strongly cemented durinodes; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (15 to 56 cm thick)

3Bqkg2--76 to 94 cm; light gray (5Y 7/2) silty clay loam, olive gray (5Y 5/2) moist; massive; slightly hard, friable, very sticky and very plastic; few very fine roots; few very fine tubular pores; common fine faint light gray (5Y 7/2) moist zones of iron depletion and common fine prominent yellowish brown (10YR 5/4) moist masses of iron accumulation; 75 percent strongly cemented durinodes; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (0 to 81 cm thick)

4Cg1--94 to 117 cm; light gray (5Y 7/2) silty clay, light olive gray (5Y 6/2) moist; moderate fine angular blocky structure; slightly hard, friable, very sticky and very plastic; few very fine roots; few very fine tubular pores; many common prominent olive (5Y 5/6) moist masses of iron accumulation; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 23 cm thick)

4Cg2--117 to 152 cm; light gray (5Y 7/2) silty clay loam, light olive gray (5Y 6/2) moist; massive; hard, firm, very sticky and very plastic; few fine prominent olive (5Y 5/6) moist masses of iron accumulation; strongly effervescent; moderately alkaline (pH 8.2)

TYPE LOCATION: Lander County, Nevada; in Grass Valley about 41 miles northeast of Austin; approximately 2,400 feet south and 2,200 feet west of the projected northeast corner of section 3, T. 23 N., R. 47 E.; USGS Little Hot Springs 7.5 minute topographic quadrangle; latitude 39 degrees 53 minutes 24 seconds N and longitude 116 degrees 40 minutes 16 seconds W; WGS84 Decimal Degrees 39.8901111 latitude, -116.671111 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section during winter, spring, and early summer, dry in late summer and fall; typic aridic soil moisture regime.
Mean annual soil temperature: 8 to 11 degrees C.
Depth to horizons with durinodes: 20 to 36 cm.

Particle-size control section - Clay content: Averages 35 to 45 percent.

A horizon
Value: 7 or 8 dry, 4 through 6 moist.
Chroma: 2 or 3, dry or moist.
Reaction: Moderately alkaline through very strongly alkaline.
Salinity (EC): 16 to 32 mmhos/cm.
Sodicity (SAR): 31 to 45.
Calcium carbonate equivalent: 5 to 15 percent.

C, Bqk, and Cg horizons
Hue: 10YR in the upper part and 2.5Y or 5Y in the lower part.
Value: 7 or 8 dry, 4 through 6 moist.
Chroma: 2 through 4 in the upper part and 1 or 2 in the lower part, dry or moist.
Texture: Stratified silty clay loam to silty clay.
Reaction: Strongly alkaline or very strongly alkaline (up to pH 9.6).
Salinity (EC): 8 to 16 mmhos/cm.
Sodicity (SAR): 13 to 30.
Durinodes: 15 to 80 percent, strongly cemented or moderately cemented in the Bqk horizons.
Effervescence: Slightly effervescent or violently effervescent.
Calcium carbonate equivalent: 1 to 10 percent.
Redoximorphic features: Occurs in most horizons as zones of iron depletion and/or masses of iron accumulation. Cg horizons have strong gleying and redox concentrations of iron.

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

GEOGRAPHIC SETTING: Skullwak soils are on lake plains. These soils formed in lacustrine deposits derived from mixed rocks. Slopes are 0 to 2 percent. Elevations range from 1,360 to 1,740 meters. The climate is arid with cool, moist winters and warm, dry summers. The mean annual precipitation is 150 to 200 mm, the mean annual temperature is 7 to 9 degrees C, and the frost-free period is 100 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Batan, Umberland, and Wendane soils. Batan and Wendane soils are fine-silty. Umberland soils do not have horizons with durinodes.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained; medium surface runoff; low saturated hydraulic conductivity. Endosaturation is present with an apparent seasonal high water table between 46 and 90 cm (shallow and moderately deep free water occurrence classes) year-round. Cumulative annual duration class is permanent. These soils are susceptible to frequent flooding for brief periods year-round.

USE AND VEGETATION: Skullwak soils are used for rangeland and wildlife habitat. The present vegetation is mainly alkali bluegrass, alkali rabbitbrush, inland saltgrass, and scattered black greasewood.

DISTRIBUTION AND EXTENT: Central and northwestern Nevada and northeastern California. These soils are not extensive with about 8,900 acres of the series mapped to date. The series concept is in MLRA 28B, while the main acreage occurs in MLRA 23.

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

SERIES ESTABLISHED: Lander County (South Part), Nevada, 1985.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A and part of the C horizons).
Durinodes - The zone from 43 to 94 cm (3Bqkg1 and 3Bqkg2 horizons).
Endosaturation feature - The condition of ground water with an upper boundary between 46 and 90 cm at certain times during normal years (parts of the 3Bqkg1 and 3Bqkg2 horizons).
Particle-size control section - The zone from 25 to 100 cm (2Bqk, 3Bqkg1, 3Bqkg2 and part of the 4Cg1 horizon).

The revision of July 2003 updated the taxonomic class from Fine, smectitic, calcareous, mesic Aeric Halaquepts.

National Cooperative Soil Survey
U.S.A.