LOCATION ITCA                    NV+ID OR

Established Series
Rev. CEJ/RLB/JVC/JBF
05/2016

ITCA SERIES

The Itca series consists of shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks. Itca soils are on hills, mountains, and plateaus. Slopes are 2 to 75 percent. The mean annual precipitation is about 360 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Lithic Argixerolls

TYPICAL PEDON: Itca extremely stony loam--forestland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 15 cm; grayish brown (10YR 5/2) extremely stony loam, very dark grayish brown (10YR 3/2) moist; weak thick platy structure parting to weak very fine granular; slightly hard, very friable, slightly sticky and nonplastic; many very fine and few fine roots; many fine interstitial pores; 30 percent gravel, 15 percent cobbles, and 15 percent stones; neutral (pH 7.2); clear wavy boundary. (3 to 18 cm thick)

A2--15 to 23 cm; brown (10YR 5/3) gravelly sandy loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium roots; common fine interstitial pores; 20 percent gravel and 5 percent cobbles; slightly alkaline (pH 7.4); abrupt wavy boundary. (0 to 15 cm thick)

Bt1--23 to 33 cm; pale brown (10YR 6/3) very gravelly clay loam, brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, very sticky and very plastic; common fine and few medium and coarse roots; common fine interstitial pores; many faint clay films lining pores and on faces of peds; 25 percent gravel and 15 percent cobbles; slightly alkaline (pH 7.4); clear irregular boundary. (8 to 23 cm thick)

Bt2--33 to 43 cm; light yellowish brown (10YR 6/4) very cobbly clay, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure; hard, firm, very sticky and very plastic; few fine, medium and coarse roots; few fine tubular pores; common distinct clay films lining pores and on faces of peds; 20 percent gravel, 20 percent cobbles, and 10 percent stones; slightly alkaline (pH 7.4); abrupt broken boundary. (8 to 25 cm thick)

R--43 cm; hard, fractured andesite.

TYPE LOCATION: Lander County, Nevada; about 22 miles east of Austin; approximately 1,950 feet east and 320 feet south of the northwest corner of section 21, T. 19 N., R. 46 E.; USGS Cape Horn 7.5 minute topographic quadrangle; latitude 39 degrees 29 minutes 54 seconds N and longitude 116 degrees 47 minutes 26 seconds W; WGS84 Decimal Degrees 39.4983333 latitude, -116.790556 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Moist in winter and spring, dry 60 to 90 consecutive days July through October; xeric moisture regime that borders on aridic.
Mean annual soil temperature: 6 to 8 degrees C.
Mollic epipedon thickness: 18 to 38 cm; includes the Bt1 horizon in some pedons.
Depth to argillic horizon: 10 to 25 cm.
Depth to bedrock: 25 to 50 cm to a lithic contact.
Other features: Abrupt boundaries exist between the A and Bt horizons.

Particle-size control section - Clay content: 35 to 45 percent when averaged; some subhorizons range up to 50 percent clay.
Rock fragments: 35 to 60 percent, when averaged, mainly gravel and cobbles; some subhorizons range up to 85 percent.

A horizon
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3.
Reaction: Neutral or slightly alkaline.

Bt1 horizon
Hue: 7.5YR or 10YR.
Value: 4 through 6 dry and 3 or 4 moist.
Chroma: 2 through 4.
Texture: Clay or clay loam.
Structure: Platy, prismatic, or subangular blocky.
Consistence: Slightly hard or hard dry, friable or firm moist, and moderately sticky or very sticky wet.
Reaction: Neutral through moderately alkaline.

Bt2 horizon
Hue: 7.5YR or 10YR.
Value: 4 through 6 dry and 3 or 4 moist.
Chroma: 2 through 4.
Texture: Clay or clay loam.
Consistence: Slightly hard or hard dry, friable or firm moist, and moderately sticky or very sticky wet.
Reaction: Neutral through moderately alkaline.
Other features: Some pedons have thin BC or C horizons consisting primarily of very soft decomposing bedrock yielding pararock fragments; In shallower pedons, the Bt horizon tongues into fractures in the bedrock contact.

COMPETING SERIES: These are the Ateron, Camool, Harlow, Jackrock, Vennob, and Wallsburg series.

Ateron soils do not have prismatic structure in the Bt2 horizon and an abrupt boundary between the A and Bt horizon. Camool soils have mollic epipedons that include the entire argillic horizon and have more than 3 percent organic matter in the A horizons. Chen and Harlow soils have mollic colors throughout the Bt horizon and also do not have prismatic structure in the argillic horizon. Jackrock soils are less than 10 cm to the argillic horizon. Vennob soils do have abrupt boundaries between the A and Bt horizons. Wallsburg soils do not have prismatic structure in the argillic horizon and contain rock fragments that are dominantly sandstone and limestone.

GEOGRAPHIC SETTING: Itca soils are on hills, mountains, and plateaus. They formed in residuum and colluvium derived from volcanic rocks. Slopes are 2 to 75 percent. Elevations range from 1,556 to 2,590 meters in Nevada. They range as low as 1,410 meters in Idaho on north aspects and 1,524 meters in Oregon. The climate is semiarid with cold, moist winters and warm, dry summers. The mean annual precipitation is 300 to 460 mm, the mean annual temperature is 4 to 8 degrees C, and the frost-free period is 50 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Borealis, Ravenswood, Softscrabble, and Walti soils. Borealis soils have an ochric epipedon and an indurated duripan at depths of 50 to 90 cm. Ravenswood and Walti soils have a lithic contact at depths of 50 to 100 cm. Softscrabble soils are very deep and loamy-skeletal.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Itca soils are used for forestland, livestock grazing, and wildlife habitat. The present vegetation is mainly a forest canopy of singleleaf pinyon and Utah juniper with an understory of mountain big sagebrush, Idaho fescue, antelope bitterbrush, and grasses.

DISTRIBUTION AND EXTENT: Central and western Nevada, southern Idaho, and southwestern Oregon. These soils are extensive. The series concept and main acreage is in MLRA 28B, while other acreage occurs in MLRAs 21, 24, 25, and 27.

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

SERIES ESTABLISHED: Lincoln County, Nevada (Meadow Valley Area), 1981.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 23 cm (A1 and A2 horizons).
Argillic horizon - The zone from 23 to 43 cm (Bt1 and Bt2 horizons).
Lithic contact - The boundary at 43 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from 23 to 43 cm (Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.