LOCATION MIRKWOOD                NV

Established Series
Rev. CAR/WED/JVC/JBF
05/2016

MIRKWOOD SERIES

The Mirkwood series consists of very shallow and shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks. Mirkwood soils are on mountains. Slopes are 15 to 75 percent. The mean annual precipitation is about 150 mm and the mean annual temperature is about 10 degrees C.

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

TYPICAL PEDON: Mirkwood extremely stony loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 20 percent stones, 15 percent cobbles, and 35 percent gravel.

A--0 to 5 cm; very pale brown (10YR 7/3) extremely stony loam, brown (10YR 5/3) moist; moderate thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; very few very fine roots; common very fine vesicular and interstitial pores; 35 percent gravel and 15 percent stones, and 10 percent cobbles; neutral (pH 7.3); clear wavy boundary. (3 to 10 cm thick)

Bt1--5 to 10 cm; pale brown (10YR 6/3) very gravelly loam, brown (10YR 4/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; very few very fine and fine roots; common very fine and fine tubular pores; common faint clay films on faces of peds; 35 percent gravel, neutral (pH 7.2); clear wavy boundary. (0 to 10 cm thick)

Bt2--10 to 23 cm; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, very friable, moderately sticky and moderately plastic; very few very fine and fine roots; common very fine and fine tubular pores; many faint and few distinct clay films on faces of peds; 40 percent gravel; neutral (pH 7.2); abrupt wavy boundary. (10 to 20 cm thick)

Bt3--23 to 28 cm; light yellowish brown (10YR 6/4) very gravelly clay loam, dark yellowish brown (10YR 4/4) moist; strong fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; very few fine roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and lining pores; 50 percent gravel; neutral (pH 6.8); abrupt irregular boundary. (0 to 10 cm thick)

R--28 cm; hard fractured basalt; thin coating of calcium carbonate in places; some roots and clay in fractures.

TYPE LOCATION: Churchill County, Nevada; about 22 miles south of Fallon; 1,300 feet east and 1,600 feet north of the projected southwest corner of section 19, T. 16 N., R. 29 E.; USGS Russell Spit 7.5 minute topographic quadrangle; 39 degrees 13 minutes 54 seconds north latitude and 118 degrees 46 minutes 40 seconds west longitude: WGS84 Decimal Degrees 39.2290000 latitude, -118.774167 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in some part for short periods during winter and spring; typic aridic soil moisture regime.
Mean annual soil temperature: 12 to 15 degrees C.
Depth to bedrock: 10 to 36 cm to a lithic contact.
Reaction: Neutral through strongly alkaline.
Salinity (EC): 0 to 2 mmhos/cm.
Sodicity (SAR); 0 to 12.

Particle-size control section - Clay content: Averages 18 to 27 percent.
Rock fragments: 35 to 50 percent, mainly gravel with some cobbles and stones.

A horizon
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 through 4.

Bt horizons
Hue: 7.5YR or 10YR.
Value: 5 through 7 dry, 4 or 5 moist.
Chroma: 2 through 4.
Texture: very gravelly loam or very gravelly clay loam.
Clay content: 25 to 35 percent.
Rock fragments: 35 to 50 percent.
Other features: Some pedons are effervescent in the lower part of the argillic horizon.

COMPETING SERIES: These are the Downeyville, Etinarg, Hoot, Theon, Tognoni, Valleycity, Vium, and Waucoba series.

Downeyville soils have horizons with identifiable secondary carbonates. Etinarg and Hoot soils have more than 50 percent rock fragments in the particle-size control section. Theon soils have abrupt boundaries between the ochric epipedon and the argillic horizon. Tognoni soils have argillic horizons with 35 to 45 percent clay. Valleycity soils have particle-size control sections which are dominated by stones, are more than 36 cm to bedrock, and have BCk horizons. Vium soils have 8 to 16 percent clay in the particle-size control section. Waucoba soils are 36 to 50 cm deep to bedrock.

GEOGRAPHIC SETTING: Mirkwood soils are on mountains. They formed in residuum and colluvium derived from volcanic rocks. Slopes are 15 to 75 percent. Elevations range from 1,400 to 1,700 meters. The climate is cool-arid with cool, moist winters and hot, dry summers. The mean annual precipitation is 100 to 200 mm, the mean annual temperature is 10 to 12 degrees C, and the frost-free period is 100 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Nemico and Old Camp soils, and the competing Theon soil. Old Camp soils have an aridic moisture regime that borders on xeric. Nemico soils are clayey, shallow to a duripan capping hard bedrock, and have natric horizons.

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

USE AND VEGETATION: Mirkwood soils are used for rangeland and wildlife habitat. The present vegetation is mainly Bailey greasewood, shadscale, littleleaf horsebrush, desert needlegrass, galleta, and Indian ricegrass.

DISTRIBUTION AND EXTENT: Western Nevada. These soils are not extensive. MLRA 27.

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

SERIES ESTABLISHED: Lyon County Area, Nevada, 1981.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 5 cm (A horizon).
Argillic horizon - The zone from 5 to 28 cm (Bt1, Bt2, and Bt3 horizons).
Lithic contact - The boundary at 28 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from the soil surface to 28 cm (A, Bt1, Bt2, and Bt3 horizons).

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National Cooperative Soil Survey
U.S.A.