LOCATION STUMOUNT                NV

Tentative Series
Rev. JBF/TM
07/2016

STUMOUNT SERIES

The Stumount series consists of very shallow and shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks. The soils are on mountains and hills. Slopes are 8 to 30 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Lithic Xeric Haplargids

TYPICAL PEDON: Stumount very flaggy fine sandy loam--rangeland. (Colors are for dry soils unless otherwise noted.) The surface is partly covered with 25 percent channers and 20 percent flagstones.

A1--0 to 3 cm; pale brown (10YR 6/3) very flaggy fine sandy loam, brown (10YR 4/3) moist; weak moderately thick platy structure; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine interstitial pores; 25 percent channers and 20 percent flagstones; neutral (pH 6.6); abrupt smooth boundary. (3 to 15 cm thick)

A2--3 to 10 cm; brown (10YR 5/3) very channery loam, dark yellowish brown (10YR 4/4) moist; moderate fine subangular blocky structure; soft, very friable, moderately sticky and slightly plastic; common very fine through medium roots; few fine tubular pores; 30 percent channers and 10 flagstones; neutral (pH 7.0); abrupt wavy boundary. (0 to 15 cm thick)

Bt1--10 to 20 cm; yellowish brown (10YR 5/4) channery loam, dark yellowish brown (10YR 4/4) moist; strong fine subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine through medium roots; few fine tubular pores; common distinct clay films on faces of peds and lining pores; 20 percent channers; neutral (pH 7.0); clear wavy boundary. (10 to 20 cm thick)

Bt2--20 to 36 cm; yellowish brown (10YR 5/4) channery clay loam, dark yellowish brown (10YR 4/4) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few fine roots; few fine tubular pores; 30 percent channers; slightly alkaline (pH 7.6); abrupt smooth boundary. (5 to 15 cm thick)

R--36 cm; volcanic bedrock, fractured in the upper 5 cm.

TYPE LOCATION: Nye County, Nevada, about 2,200 feet north and 400 feet west of the southeast corner of section 34, T. 12 N., R. 47 E.; USGS Mosquito Creek 7.5 minute topographic quadrangle; latitude 38 degrees 50 minutes 03 seconds N and longitude 116 degrees 39 minutes 50 seconds W; WGS84 Decimal Degrees 38.8341667 latitude, -116.6638889 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry; dry in summer and fall, moist in winter and spring and for 10 to 20 days cumulative July to October following convection storms; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 12 degrees C.
Depth to bedrock: 18 to 36 cm.

Particle-size control section - Clay content - Averages 18 to 25 percent.
Rock fragments - Averages 25 to 35 percent, mainly volcanic channers and flagstones with 15 to 25 percent of the channer and gravel size material in the 2 to 5 mm size fraction.

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

Bt horizons:
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4.
Texture: loam or clay loam; subhorizons of clay are above the lithic contact in some pedons.
Clay content: Averages 25 to 35 percent.
Reaction: Neutral or slightly alkaline.
Carbonates: Carbonates are present at the lithic contact and in bedrock fractures in some pedons.

COMPETING SERIES: These are the Banbury, Bombadil, Dougal, Fubble, Jaybee, Kreza, and Meninik series.

None of these soils are dominated by channers and flagstones. In addition, Banbury and Bombadil soils have less than 25 percent rock fragments in the particle-size control section. Fubble soils are 36 to 50 cm deep. Jaybee soils have argillic horizons with 35 to 45 percent clay. Kreza soils have 15 to 25 percent clay in the particle-size control section. Meninik soils have textures that are dominantly silt loam and silty clay loam in the argillic horizon.

GEOGRAPHIC SETTING: Stumount soils are on mountains and hills. These soils formed in residuum and colluvium derived from volcanic rocks. Slopes are 8 to 30 percent. Elevations are 2,135 to 2,625 meters. The climate is cool, semiarid with warm summers and cool, moist winters. The mean annual precipitation is 250 to 300 mm, the mean annual temperature is 7 to 10 degrees C, and frost-free period is 90 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cropper and Bellenmine soils. These soils have mollic epipedons.

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

USE AND VEGETATION: Livestock grazing and wildlife habitat. The present vegetation is mainly black sagebrush, bottlebrush squirreltail, bluegrass, Thurber's needlegrass, Indian ricegrass and blue grama.

DISTRIBUTION AND EXTENT: South-central, Nevada, MLRA 29. These soils are not extensive.

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

SERIES PROPOSED: Nye County, Nevada, Toiyabe National Forest, Nevada, Central Part, 1994.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 10 cm (A1 and A2 horizons).
Argillic horizon - The zone from 10 to 36 cm (Bt1 and Bt2 horizons).
Lithic contact - The contact at 36 cm (R layer).
Particle-size control section - The zone from the soil surface to 36 cm (A1, A2, Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.