LOCATION ROCHPAH                 NV

Established Series
Rev. DJM/RLB/JBF
06/2016

ROCHPAH SERIES

The Rochpah series consists of shallow, well drained soils that formed in residuum and colluvium derived from volcanic tuff. The Rochpah soils are on mountain and hill side slopes and rock pediments. Slopes are 4 to 50 percent. The mean annual precipitation is about 150 mm and the mean annual temperature is about 13 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Haplocalcids

TYPICAL PEDON: Rochpah very gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The surface is partially covered with 50 percent gravel and 10 percent cobbles.

A--0 to 10 cm; light brownish gray (10YR 6/2) very gravelly sandy loam, brown (10YR 4/3) moist; moderate thin platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine interstitial pores; 10 percent cobbles, 30 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (8 to 15 cm thick)

Bk1--10 to 23 cm; light brownish gray (10YR 6/2) very gravelly sandy loam, brown (10YR 4/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine and fine and few medium roots; many very fine interstitial and common very fine tubular pores; many thin carbonate coats on undersides of rock fragments; 5 percent cobbles, 30 percent gravel; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (10 to 28 cm thick)

Bk2--23 to 48 cm; very pale brown (10YR 7/3) very cobbly sandy loam, brown (10YR 5/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium roots; many very fine interstitial and few fine tubular pores; many thick carbonate coats and pendants on undersides and sides of rock fragments; 30 percent cobbles, 15 percent gravel; violently effervescent; strongly alkaline (pH 8.8); abrupt smooth boundary. (10 to 25 cm thick)

R--48 cm; hard volcanic tuff bedrock.

TYPE LOCATION: Lincoln County, Nevada; approximately 1/2 mile southeast of Southeast Reservoir in southern Delamar Valley; about 1250 feet west and 1000 feet south of the projected northeast corner of section 33, T. 7 S., R. 63 E.; USGS Delamar Lake 7.5 minute topographic quadrangle; latitude 37 degrees 18 minutes 1 second N and longitude 114 degrees 55 minutes 31 seconds W; WGS84 Decimal Degrees 37.3002778 latitude, -114.9252778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist for short periods during winter and early spring, and in some part for 10 to 20 days cumulative following summer convection storms during July through October; typic aridic soil moisture regime.
Mean annual soil temperature: 13 to 15 degrees C.
Depth to bedrock: 36 to 50 cm.

Particle-size control Section - Clay content: 5 to 18 percent.
Rock fragments: 35 to 60 percent, including 0 to 30 percent cobbles.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3.

Bk horizons
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4.
Texture: Very gravelly sandy loam, very cobbly sandy loam, or very gravelly coarse sandy loam.
Reaction: Moderately alkaline or strongly alkaline.
Calcium Carbonate equivalent by weight: 15 to 30 percent.

COMPETING SERIES: These are the Crotoncanyon, Hoovers and Tuffman series.

Crotoncanyon soils have 27 to 40 percent clay in the particle-size control section. Hoovers soils have a mean annual soil temperature range from 11 to 13 degrees C. and it contains 18 to 34 percent clay in the particle-size control section. Tuffman soils have average more than 60 percent rock fragments.

GEOGRAPHIC SETTING: Rochpah soils are on mountain and hill side slopes and on rock pediments. These soils formed in residuum and colluvium derived from volcanic tuffs. Slopes are 4 to 50 percent. Elevations are 1,160 to 1,590 meters. The climate is cool, arid with cool, moist winters and hot, intermittently moist summers. The mean annual precipitation is 125 to 200 mm, mean annual temperature is 12 to 14 degrees C, and the frost-free season is 150 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hollace, Pintwater, Winklo and Wyva soils. Hollace, Wyva, and Winklo soils have argillic horizons. Hollace soils have petrocalcic horizons. Winklo soils have less than 35 percent rock fragments in the control section. Pintwater soils have silica coatings on underside of rock fragments.

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

USE AND VEGETATION: Livestock grazing and wildlife habitat. The present vegetation is mainly blackbrush, Nevada ephedra, horsebrush, desert needlegrass, and Indian ricegrass.

DISTRIBUTION AND EXTENT: Southeastern Nevada. These soils are not extensive. MLRA 29.

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

SERIES ESTABLISHED: Lincoln County, Nevada, South Part, 1992.

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 Bk1 horizons).
Calcic horizon - The zone from 10 to 48 cm (Bk1 and Bk2 horizons).
Lithic contact - The boundary at 48 cm. (R layer)
Particle-size control section - The zone from 25 to 48 cm (Bk horizon).

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National Cooperative Soil Survey
U.S.A.