LOCATION MCWATT                  NV+CA

Established Series
Rev. SES-JBF-TM-JVC
01/2020

MCWATT SERIES

The Mcwatt series consists of deep, somewhat excessively drained soils that formed in alluvium derived from basalt. Mcwatt soils are on plateaus and lake terraces. Slopes are 4 to 50 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Xeric Haplocambids

TYPICAL PEDON: Mcwatt extremely stony fine sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partly covered with 15 percent stones, 20 percent cobbles, and 20 percent gravel.

A--0 to 10 cm; pale brown (10YR 6/3) extremely stony fine sandy loam, dark brown (10YR 3/3) moist; moderate thin and medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine and fine vesicular pores; 15 percent stones, 20 percent cobbles and 30 percent gravel; neutral (pH 6.8); clear wavy boundary. (5 to 13 cm thick)

Bw1--10 to 25 cm; light brownish gray (10YR 6/2) extremely stony fine sandy loam, dark brown (10YR 3/3) moist; strong medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; many very fine tubular pores; 15 percent stones 20 percent cobbles, and 30 percent gravel; neutral (pH 7.2); clear wavy boundary. (0 to 20 cm thick)

Bw2--25 to 51 cm; pale brown (10YR 6/3) extremely gravelly fine sandy loam, dark brown (10YR 3/3) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine, common fine and medium roots; many very fine interstitial pores; 3 percent stones, 20 percent cobbles and 50 percent gravel; neutral (pH 7.2); clear irregular boundary. (18 to 30 cm thick)

2Cqk1--51 to 64 cm; light yellowish brown (10YR 6/4) extremely cobbly loamy sand, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium and few coarse roots; many very fine interstitial pores; 10 percent stones, 35 percent cobbles and 40 percent gravel; secondary carbonates and silica segregated as thin (<0.5 millimeter) coats on 30 percent of the bottoms of rock fragments; slightly alkaline (pH 7.6); clear irregular boundary. (13 to 58 cm thick)

2Cqk2--64 to 112 cm; light yellowish brown (10YR 6/4) extremely gravelly sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine, few medium and coarse roots; many very fine interstitial pores; 5 percent stones, 15 percent cobbles, and 50 percent gravel; secondary carbonates and silica segregated as thin (<0.5 mm) coats on 60 percent of the bottoms of rock fragments; slightly alkaline (pH 7.6); abrupt irregular boundary. (10 to 31 inches thick)

3R--112 cm; hard, vesicular basalt; silica and secondary carbonate coats lining few fractures.

TYPE LOCATION: Washoe County, Nevada; in the Black Hills about 3.5 miles south of Road 8A along the powerline in Long Valley; about 2,130 feet south and 2,000 feet west of the northeast corner section 28, T. 42 N., R. 20 E.; USGS Painted Point 7.5 minute topographic quadrangle; latitude 41 degrees 31 minutes 58.8 seconds N and longitude 119 degrees 44 minutes 35.5 seconds W; WGS84 Decimal Degrees 41.5330000 latitude, -119.7431944 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture; Usually moist in winter and spring, dry from mid-June through October; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 12 degrees C.
Depth to sandy-skeletal material: 38 to 66 cm.
Depth to identifiable secondary carbonates - 17 to 29 inches.
Depth to bedrock; 100 to 150 cm to a lithic contact.

Particle-size control section - Clay content: Averages 2 to 8 percent.
Rock fragments: 60 to 75 percent, mainly cobbles and gravel. Lithology of fragments is mainly volcanic rocks such as basalt.

A horizon
Hue: 10YR or 2.5Y.
Reaction: Neutral or slightly alkaline.

Bw horizons
Value: 6 or 7 dry, 3 through 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Extremely gravelly fine sandy loam, extremely cobbly fine sandy loam, or extremely gravelly sandy loam.
Clay content: 8 to 15 percent.
Reaction: Neutral or slightly alkaline.

2Cqk horizons
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Extremely cobbly loamy sand, extremely gravelly sand, or extremely gravelly loamy sand.
Clay content: 0 to 5 percent.
Rock fragments: 60 to 80 percent, mainly cobbles and gravel.
Reaction: Slightly alkaline or moderately alkaline.
Effervescence: Noneffervescent matrix.
Identifiable secondary carbonates: Few to many less than 0.5 millimeter thick carbonate and silica coats on bottoms of rock fragments.
Calcium carbonate equivalent: 1 to 3 percent.

COMPETING SERIES: These are the Broncho, Malaga, McConnel, Mcnye, and Ragnel series.

Broncho, Malaga, McConnel, and Ragnel soils are very deep. Mcnye soils are 5 to 15 inches deep to disseminated secondary carbonates.

GEOGRAPHIC SETTING: Mcwatt soils are on plateaus and lake terraces. These soils formed in alluvium derived from basalt. Slopes are 4 to 50 percent. Elevations range from 1,370 to 1,850 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 mm, the mean annual temperature is 7 to 8 degrees C, and the frost-free period is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Langston, Old Camp, and Paypoint soils. Langston soils are fine-loamy over sandy or sandy-skeletal and have argillic horizons. Old Camp soils are loamy-skeletal, shallow to lithic contacts, and have argillic horizons. Paypoint soils are ashy over sandy or sandy-skeletal and have argillic horizons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat excessively drained; low surface runoff; high saturated hydraulic conductivity.

USE AND VEGETATION: Mcwatt soils are used for rangeland and wildlife habitat. The present vegetation is mainly Wyoming big sagebrush, bottlebrush squirreltail, Thurber's needlegrass, and spiny hopsage.

DISTRIBUTION AND EXTENT: Northwestern Nevada and northeastern California. These soils are moderately extensive. MLRA 23.

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

SERIES ESTABLISHED: Washoe County, Nevada (North Part), 1995.

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 Bw1 horizons).
Cambic horizon - The zone from 10 to 51 cm (Bw1 and Bw2 horizons).
Lithic contact - The boundary at 112 cm to underlying hard, unweathered bedrock (3R layer).
Particle-size control section - The zone from 25 to 100 cm (Bw2 and 2Cqk1 horizons and part of the 2Cqk2 horizon).

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National Cooperative Soil Survey
U.S.A.