LOCATION SOFTSCRABBLE            NV+CA

Established Series
Rev. JBF/TM
06/2017

SOFTSCRABBLE SERIES

The Softscrabble series consists of very deep, well drained soils that formed in residuum and colluvium derived mainly from volcanic rocks. Softscrabble soils are on plateaus, hills, and mountains. Slopes are 4 to 75 percent. The mean annual precipitation is about 400 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Pachic Argixerolls

TYPICAL PEDON: Softscrabble very stony loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 3 cm; brown (10YR 4/3) very stony loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine through coarse roots; many very fine and fine tubular pores; 25 percent gravel, 5 percent cobbles, and 10 percent stones; neutral (pH 7.0) clear smooth boundary. (3 to 28 cm thick)

A2--3 to 23 cm; dark brown (10YR 3/3) extremely gravelly loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine through coarse roots; many very fine and fine tubular pores; 55 percent gravel, 5 percent cobbles, and 5 percent stones; neutral (pH 7.0); clear smooth boundary. (0 to 36 cm thick)

Bt1--23 to 48 cm; brown (10YR 5/3) very cobbly clay loam, dark brown (10YR 3/3) moist; strong fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine through medium roots; common fine and very fine tubular pores; many distinct clay films on faces of peds and lining pores; 10 percent gravel, 20 percent cobbles, and 5 percent stones; neutral (pH 6.8); gradual wavy boundary. (18 to 50 cm thick)

Bt2--48 to 76 cm; brown (10YR 5/3) extremely cobbly clay loam, dark brown (10YR 3/3) moist; strong fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine through medium roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and lining pores; 5 percent gravel, 55 percent cobbles and 5 percent stones; neutral (pH 6.8); gradual smooth boundary. (10 to 46 cm thick)

2Bt1--76 to 102 cm; yellowish brown (10YR 5/4) clay loam, dark yellowish brown (10YR 3/4) moist; strong fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine through medium roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and lining pores; 1 percent gravel; neutral (pH 6.6); clear wavy boundary. (0 to 64 cm thick)

2Bt2--102 to 152 cm; yellowish brown (10YR 5/4) gravelly clay loam, dark yellowish brown (10YR 3/4) moist; strong fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; common fine distinct light olive brown (2.5Y 5/6) moist mottles; many distinct clay films on faces of peds and lining pores; 15 percent gravel; neutral (pH 6.6); gradual smooth boundary. (0 to 30 cm thick)

3Bt3--152 to 198 cm; yellowish brown (10YR 5/4) loam, dark yellowish brown (10YR 3/4) moist; strong fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; common fine prominent strong brown (7.5YR 5/8) moist mottles; many distinct clay films on faces of peds and lining pores; 5 percent gravel; neutral (pH 6.6). (0 to 64 cm thick); clear, wavy boundary

3Cr--198 cm; highly weathered andesite.

TYPE LOCATION: Washoe County, Nevada; in the Virginia Mountains between Paiute Canyon and Hardscrabble Canyon; about 500 feet west and 1,600 feet south of the northeast corner of section 14, T. 24 N., R. 20 E.; USGS Tule Peak 7.5 minute topographic quadrangle; latitude 39 degrees 57 minutes 00 seconds N and longitude 119 degrees 41 minutes 43 seconds W; UTM Zone 11, 269749e, 4425686n; WGS84 Decimal Degrees 39.9500000 latitude, -119.6952778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry mid-July to early October for 75 to 90 consecutive days in the four months following the summer solstice; xeric soil moisture regime.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 50 to 97 cm; includes the Bt1 and Bt2 horizons.
Depth to base of argillic horizon: 150 to 200 cm.
Depth to bedrock: 150 to 200 cm to a paralithic contact. The paralithic materials below the contact are weathered volcanic rocks such as andesite or andesitic tuff.
Reaction: Slightly acid or neutral.

Particle-size control section - Clay content: Averages 27 to 35 percent.
Rock fragments: Averages 35 to 70 percent, mainly gravel and cobbles with a few stones. Lithology of fragments are volcanic rocks such as andesite or tuff-breccia.

A horizons
Hue: 10YR or 7.5YR.
Value: 3 through 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 to 5 percent.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 2 through 4 (4 in lower part only).
Texture: Very cobbly clay loam, extremely cobbly clay loam, very gravelly clay loam, or extremely gravelly clay loam; some pedons have subhorizons below 76 cm with clay loam, gravelly clay loam, very gravelly clay loam, or loam.
Rock fragments: 35 to 70 percent; some pedons have subhorizons with no rock fragments.
Structure: Angular blocky or subangular blocky.
Consistence: Slightly hard or hard, dry; friable or firm, moist; slightly sticky or moderately sticky and slightly plastic or moderately plastic wet.
Organic matter content: 1 or 2 percent in the upper horizons.

COMPETING SERIES: These are the Bullump, Bullvaro, Burchflat, Camelback, Chrisflat, Dogbed, Dooh, Erig, Krenka, Leroman, Lockgate, Murain, Nutval, Snyderville, Softback, Staberg, Vetagrande, and Vipont series.

Bullump soils have mollic epipedons that do not include most subhorizons of the argillic horizon, are dominated by gravel in the particle-size control section, and have rock fragments of mixed lithology. Bullvaro, Dooh, Nutval, and Vetagrande soils have an aridic moisture regime. Burchflat and Vipont soils are moderately deep to lithic contacts. Camelback soils have rock fragments which are mainly quartzite and are dominated by cobbles in the particle-size control section. Chrisflat soils average 18 to 25 percent clay in the particle-size control section and do not have paralithic contacts within 200 cm of the soil surface. Dogbed soils average 18 to 27 percent clay in the particle-size control section. Erig soils are deep to lithic contacts. Krenka soils have less than 35 percent rock fragments in the upper part of the argillic horizon. Leroman and Staberg soils are moderately deep to paralithic contacts. Lockgate soils are deep to paralithic contacts. Murain soils are dominated by stones, average 18 to 25 percent rock fragments in the particle-size control section, and do not have paralithic contacts within 200 cm of the soil surface. Snyderville soils have depth to base of the argillic horizon of less than 90 cm. Softback soils have mollic epipedons that do not include the upper Bt horizons.

GEOGRAPHIC SETTING: Softscrabble soils are on plateaus, hills, and mountains. They typically occur on backslope positions. These soils formed in residuum and colluvium derived from volcanic rocks with some areas of chert, quartzite, and shale. Slopes are 4 to 75 percent. Elevations range from 1,465 to 2,505 meters. The climate is subhumid-continental with cold, moist winters and warm, dry summers. The mean annual precipitation is 360 to 500 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Burnborough, Chad, Gabica, Indiano, and Thulepah soils. Burnborough soils have mollic epipedons that are less than 50 cm thick. Chad soils are fine. Gabica soils have bedrock at less than 50 cm. Indiano soils are moderately deep to lithic contacts. Thulepah soils have less than 35 percent rock fragments in the particle-size control section.

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

USE AND VEGETATION: Softscrabble soils are used for livestock grazing and wildlife habitat. The vegetation is mountain big sagebrush, golden currant, mulesear wyethia, and Douglas rabbitbrush.

DISTRIBUTION AND EXTENT: Western Nevada and northeastern California. These soils are extensive with about 154,000 acres of the series mapped to date. The original series concept is in MLRA 26, while other acreage occurs in MLRAs 23, 24, 25, and 28B.

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

SERIES ESTABLISHED: Washoe County (South Part), Nevada, 1980.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 76 cm (A1, A2, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 23 to 198 cm (Bt1, Bt2, 2Bt1, 2Bt2, and 2Bt3 horizons).
Paralithic contact - The boundary at 198 cm to underlying weathered bedrock (3Cr layer).
Particle-size control section - The zone from 23 to 73 cm (Bt1 and part of the Bt2 horizons).

ADDITIONAL DATA: A pedon of Softscrabble from the central part of Washoe County, Nevada has full characterization by the Soil Survey Laboratory (SSL), Lincoln, NE, as soil survey sample number S86NV-031-005 (pedon # 86P0907).

User Pedon ID: S1978NV031009.

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National Cooperative Soil Survey
U.S.A.