LOCATION BAKSCRATCH              NV+CA

Established Series
Rev. EWB-TM-JVC-JBF
02/2017

BAKSCRATCH SERIES

The Bakscratch series consists of shallow, well drained soils that formed in residuum and colluvium derived from granitic rocks. Bakscratch soils are on mountains. Slopes are 15 to 75 percent. The mean annual precipitation is about 500 mm and the mean annual temperature is about 4 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, shallow Xeric Argicryolls

TYPICAL PEDON: Bakscratch extremely stony coarse sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with about 35 percent stones, 15 percent cobbles, and 15 percent gravel.

A1--0 to 8 cm; dark grayish brown (10YR 4/2) extremely stony coarse sandy loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; common very fine tubular and interstitial pores; 20 percent stones, 10 percent cobbles, and 30 percent gravel; slightly acid (pH 6.3); clear wavy boundary. (5 to 10 cm thick)

A2--8 to 18 cm; brown (10YR 4/3) very gravelly coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots; common very fine tubular and interstitial pores; 5 percent cobbles and 50 percent gravel; neutral (pH 6.7); clear wavy boundary. (8 to 13 cm thick)

Bt--18 to 46 cm; pale brown (10YR 6/3) very gravelly coarse sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine, fine and medium roots; common very fine tubular and fine interstitial pores; common faint clay bridges between sand grains; 5 percent cobbles and 45 percent gravel; neutral (pH 6.7); clear irregular boundary. (15 to 48 cm thick)

Cr--46 cm; weathered and fractured granitic rock; roots and fine-earth in fractures.

TYPE LOCATION: Douglas County, Nevada; in the Pine Nut Mountains; approximately 2,100 feet north and 300 feet east of the southwest corner of section 10, T. 11 N., R. 22 E.; USGS Double Spring 7.5 minute topographic quadrangle; latitude 38 degrees 49 minutes 46.6 seconds N and longitude 119 degrees 30 minutes 42 seconds W; WGS84 Decimal Degrees 38.8296167 latitude, -119.5116667 longitude..

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry from July through October; xeric soil moisture regime that borders on aridic.
Mean annual soil temperature: 4 to 8 degrees C.
Mean summer soil temperature: 12 to 15 degrees C.
Mollic epipedon thickness: 18 to 36 cm; may include an upper subhorizon of the argillic or the entire argillic horizon in some pedons.
Depth to bedrock: 36 to 50 cm to a paralithic contact. The paralithic materials below the contact are weathered granitic rock.
Reaction: Slightly acid or neutral.

Particle-size control section - Clay content: 12 to 18 percent.
Rock fragments: 35 to 60 percent, dominantly fine gravel. Lithology of fragments are granitic rocks such as granite or granodiorite.

A horizons
Value: 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 2 to 4 percent.

Bt horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Clay content: 12 to 18 percent.
Consistence: Slightly hard or hard, dry.

COMPETING SERIES: These are the Badgercamp and Hiridge series.

Badgercamp soils are dominated by gravel of volcanic lithology larger than 5 mm in diameter. Hiridge soils have 25 to 35 percent clay in the particle-size control section.

GEOGRAPHIC SETTING: Bakscratch soils are on mountains. They typically occur on shoulder and backslope positions. They formed in residuum and colluvium derived from granitic rocks. Slopes are 15 to 75 percent. Elevations range from 2,316 to 3,350 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 400 to 760 mm, the mean annual temperature is 2 to 6 degrees C, and the frost-free period is 50 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bullville and Delhew soils. Bullville soils are loamy-skeletal, moderately deep to paralithic contacts, and have mollic epipedons and argillic horizons. Delhew soils are loamy-skeletal, very deep, and have argillic horizons and thick mollic epipedons.

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

USE AND VEGETATION: Bakscratch soils are used for rangeland and wildlife habitat. The present vegetation is mainly curl-leaf mountain mahogany, mountain big sagebrush, spike fescue, and bluegrass.

DISTRIBUTION AND EXTENT: Western Nevada and eastern California. These soils are not extensive with about 2,300 acres of the series mapped to date. The series concept and main acreage is in MLRA 26, while other acreage occurs in MLRA 22A.

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

SERIES ESTABLISHED: Toiyabe National Forest Area, California, 2006. The series was proposed in Douglas County, Nevada, 1996.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 18 cm (A1 and A2 horizons).
Argillic horizon - The zone from 18 to 46 cm (Bt horizon).
Paralithic contact - The boundary to underlying soft, weathered bedrock at 46 cm (Cr layer).
Particle-size control section - The zone from 18 to 46 cm (Bt horizon).

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National Cooperative Soil Survey
U.S.A.