LOCATION CHALCO NV+CA

Established Series
Rev. JBF/TM
03/2017

CHALCO SERIES

The Chalco series consists of shallow, well drained soils that formed in pedisediment or colluvium over residuum derived from volcanic rocks. Chalco soils are on rock pediments, plateaus, and hills. Slopes are 0 to 50 percent. The mean annual precipitation is about 250 mm and the mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Clayey, smectitic, mesic, shallow Xeric Haplargids

TYPICAL PEDON: Chalco gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted). The soil surface is covered with about 35 percent gravel, 5 percent cobbles, and 1 percent stones.

A--0 to 8 cm; light brownish gray (10YR 6/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak medium platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine roots; many fine vesicular pores; 1 percent stones, 1 percent cobbles, and 20 percent gravel; neutral (pH 6.6); abrupt smooth boundary. (3 to 13 cm thick)

Bt1--8 to 30 cm; dark yellowish brown (10YR 4/4) clay, dark yellowish brown (10YR 4/4) moist; strong medium prismatic structure; extremely hard, very firm, very sticky and very plastic; few very fine through medium roots; few very fine through medium tubular pores; common prominent clay films on faces of peds; neutral (pH 6.8); gradual smooth boundary. (8 to 40 cm thick)

2Bt2--30 to 38 cm; yellowish brown (10YR 5/4) paragravelly clay, dark yellowish brown (10YR 4/4) moist; massive; hard, very firm, moderately sticky and moderately plastic; very few roots; very few pores; common distinct clay films lining pores; 15 percent weathered tuff fragments; neutral (pH 6.8); abrupt wavy boundary. (3 to 15 cm thick)

2Cr--38 cm; weathered tuff.

TYPE LOCATION: Washoe County, Nevada; in northwest Reno west of Peavine Creek; approximately 1,900 feet west and 1,620 feet north of the southeast corner of section 5, T. 19 N., R. 19 E.; USGS Reno 7.5 minute topographic quadrangle; latitude 39 degrees 32 minutes 16 seconds N and longitude 119 degrees 52 minutes 13 seconds W; WGS84 Decimal Degrees 39.5377778 latitude, -119.8702778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and early spring, dry in summer and fall; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 10 to 14 degrees C.
Ochric epipedon thickness: 3 to 13 cm.
Depth to bedrock: 25 to 50 cm to a paralithic contact. The paralithic materials below the contact are weathered volcanic rocks such as tuff or andesite.

Particle-size control section - Clay content: Averages 35 to 60 percent.
Rock or pararock fragments: 0 to 15 percent, mainly gravel. Lithology of fragments is volcanic rocks such as tuff or andesite.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Structure: Platy, granular, or subangular blocky.
Reaction: Slightly acid through slightly alkaline.

Bt horizons
Value: 4 through 6 dry, 3 through 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Clay, silty clay, or paragravelly clay.
Clay content: 40 to 60 percent.
Rock fragments: 0 to 15 percent.
Pararock fragments: 0 to 15 percent.
Structure: Commonly prismatic but angular blocky in some pedons.
Reaction: Slightly acid through moderately alkaline.
Other features: Less than 15 percent sand coarser than very fine sand.

C horizon (when present)
Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 through 4, dry or moist.

COMPETING SERIES: These are the Bedzee, Brisbois, Espint, Gumble, and Xman series.

Bedzee soils have 15 to 35 percent rock fragments in the argillic horizon. Brisbois soils have identifiable secondary carbonates in the argillic horizon. Espint soils have Bt1 horizons with 27 to 40 percent clay and are moist for 10 to 20 days during the summer. Gumble soils have mean annual soil temperature of 8 to 10 degrees C. and have more than 15 percent fine sand and coarser in the argillic horizon. Xman soils have more than 15 percent fine sand and coarser in the argillic horizon and have hard bedrock, below the weathered bedrock, at depths of 50 to 100 cm.

GEOGRAPHIC SETTING: Chalco soils are on rock pediments, plateaus, and hills. They typically occur on footslope and backslope positions. These soils formed in pedisediment or colluvium over residuum derived from volcanic rocks. Slopes are 0 to 50 percent. Elevations range from 1,345 to 2,040 meters. The mean annual precipitation is 200 to 360 mm, the mean annual temperature is 8 to 9 degrees C, and the frost-free period is 60 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Reno and Waspo soils. Reno soils are moderately deep to duripans. Waspo soils are moderately deep to paralithic contacts and have a horizon with slickensides.

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

USE AND VEGETATION: Chalco soils are used for livestock grazing, wildlife habitat, and some urban development. The vegetation is mainly low sagebrush, rabbitbrush, Nevada ephedra, bottlebrush squirreltail, and some antelope bitterbrush.

DISTRIBUTION AND EXTENT: Western Nevada and northeastern California. These soils are moderately extensive. The series concept and main acreage is in MLRA 26, while other acreage occurs in MLRA 23.

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

SERIES ESTABLISHED: Washoe County (South Part), Nevada, 1980.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 8 cm (A horizon).
Argillic horizon - The zone from 8 to 38 cm (Bt1 and 2Bt2 horizons).
Paralithic contact - The boundary at 38 cm to underlying soft, weathered bedrock (2Cr layer).
Particle-size control section - The zone from 8 to 38 cm (Bt1 and 2Bt2 horizons).

ADDITIONAL DATA: User Pedon ID: 2002NV031051.

National Cooperative Soil Survey
U.S.A.