LOCATION TERCA NV

Established Series
Rev. EWB/WED/JVC
06/2017

TERCA SERIES

The Terca series consists of shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks. Terca soils are on hills and mountains. Slopes are 15 to 75 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Aridic Lithic Argixerolls

TYPICAL PEDON: Terca very stony loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with approximately 10 percent stones, 10 percent cobbles, and 15 percent gravel.

A--0 to 8 cm; grayish brown (10YR 5/2) very stony loam, very dark grayish brown (10YR 3/2) moist; strong very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine to fine roots; common very fine interstitial pores; 20 percent gravel, 5 percent cobbles, and 5 percent stones; slightly alkaline (pH 7.4); abrupt smooth boundary. (5 to 13 cm thick)

Bt1--8 to 13 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; strong very fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine interstitial and few very fine tubular pores; common faint colloid coats on mineral grains and clay bridges between sand grains; 20 percent gravel; slightly alkaline (pH 7.4); abrupt smooth boundary. (5 to 10 cm thick)

Bt2--13 to 25 cm; brown (10YR 4/3) gravelly clay loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine, few medium roots; many very fine tubular pores; many faint colloid coats on mineral grains and clay bridges between sand grains; 20 percent gravel and 5 percent stones; slightly alkaline (pH 7.4); clear wavy boundary. (8 to 15 cm thick)

Bt3--25 to 43 cm; brown (10YR 4/3) gravelly clay loam, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and few fine roots; many very fine tubular pores; many faint colloid coats on mineral grains and clay bridges between sand grains; few faint clay films on faces of peds; 25 percent gravel; neutral (pH 7.2); abrupt wavy boundary. (10 to 20 cm thick)

R--43 cm; hard basalt; fractured with some roots and soil in fractures in the upper part.

TYPE LOCATION: Washoe County, Nevada; about 3.5 miles south of Honey Lake Valley above Fish Springs Creek; approximately 2,400 feet south and 1,600 feet east of the northwest corner of section 11, T. 25 N., R. 18 E.; USGS State Line Peak 7.5 minute topographic quadrangle; latitude 40 degrees 02 minutes 58 seconds N and longitude 119 degrees 56 minutes 13 seconds W; WGS84 Decimal Degrees 40.0487222 latitude, -119.9369444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in the summer and fall; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 9 to 11 degrees C.
Mollic epipedon thickness: 18 to 28 cm; includes the upper part of the argillic horizon.
Depth to bedrock: 36 to 50 cm to a lithic contact; the bedrock is fractured and weathered in the upper 3 to 15 cm with some roots and soil material in the fractures.
Reaction: Neutral or slightly alkaline.

Particle-size control section - Clay content: 27 to 35 percent;
Rock fragments: 15 to 35 percent, dominantly medium to coarse (15 to 75 mm diameter) gravel.

A horizon
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 or 2 percent.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist, with 2 dominantly in the Bt1 horizon.
Texture: Gravelly clay loam; some pedons have gravelly loam in the Bt1 horizon.
Clay content: 27 to 35 percent.
Rock fragments: 15 to 35 percent.
Organic matter content: 0.5 to 2 percent.

COMPETING SERIES: These are the Adinot, Cooperopolis, Laric, Marlic, and McQuarrie series.

Adinot soils have 35 to 40 percent clay in the lower part of the argillic horizon and have a mollic epipedon that includes the entire argillic horizon. Cooperopolis soils average less than 15 percent rock fragments in the particle-size control section and have ashy modified surface textures. Laric soils are 13 to 30 cm to a lithic contact. Malinda Marlic soils have 35 to 40 percent clay in the lower part of the argillic horizon. McQuarrie soils have a subhorizon in the lower part of the argillic horizon with identifiable secondary carbonates and moderately alkaline or strongly alkaline reaction.

GEOGRAPHIC SETTING: Terca soils are on hills and mountains. They typically occur on shoulder and backslope positions. These soils formed in residuum and colluvium derived from volcanic rocks. Slopes are 15 to 75 percent. Elevations range from 1,495 to 1,895 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 350 mm, the mean annual temperature is 7 to 9 degrees C, and the frost-free period is 70 to 95 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Devada and Perla soils. Devada soils are clayey. Perla soils are clayey and are moderately deep to bedrock.

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

USE AND VEGETATION: Terca soils are used for livestock grazing and wildlife habitat. The present vegetation is mainly mountain big sagebrush, antelope bitterbrush, bluebunch wheatgrass, and Thurber's needlegrass.
DISTRIBUTION AND EXTENT: Northwestern Nevada. These soils are moderately extensive. The series concept and main acreage is in MLRA 26, while other acreage occurs in MLRAs 23.

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

SERIES ESTABLISHED: Washoe County, Nevada (Central Part), 1990. The name is coined.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 25 cm (A1, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 8 to 43 cm (Bt1, Bt2, and Bt3 horizons).
Lithic contact - The boundary at 43 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from 8 to 43 cm (Bt1, Bt2, and Bt3 horizons).

Classification was updated to 11th edition on 07/2011 changed Lithic Argixerolls to Aridic Lithic Argixerolls.

ADDITIONAL DATA: User pedon ID 2007NV031001.

National Cooperative Soil Survey
U.S.A.