LOCATION ANAWALT OR+CA NV

Established Series
Rev. JVC-JBF
02/2012

ANAWALT SERIES

The Anawalt series consists of shallow, well drained soils that formed in colluvium and residuum derived from volcanic rocks with some loess and volcanic ash influence in the surface. Anawalt soils are on lava plains, plateaus, hills, and mountains. Slopes are 0 to 50 percent. The mean annual precipitation is about 250 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Clayey, smectitic, frigid Lithic Xeric Haplargids

TYPICAL PEDON: Anawalt stony silt loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 4 cm; light brownish gray (10YR 6/2) stony silt loam, dark grayish brown (10YR 4/2) moist; weak very fine granular structure; soft, friable, nonsticky and nonplastic; few roots; many very fine pores; 15 percent basalt stones; moderately alkaline (pH 8.0); abrupt smooth boundary.

A2--4 to 15 cm; light brownish gray (10YR 6/2) stony silt loam, very dark grayish brown (10YR 3/2) moist; strong thick platy structure; slightly hard, friable, slightly sticky and slightly plastic; few roots; many very fine pores; 15 percent basalt stones; moderately alkaline (pH 8.0); abrupt smooth boundary. (Combined thickness of the A horizon is 5 to 28 cm thick)

Bt1--15 to 41 cm; brown (10YR 5/3) gravelly silty clay, dark yellowish brown (10YR 3/4) moist; strong fine angular blocky structure; hard, very firm, very sticky and very plastic; many roots; few very fine tubular pores; few faint clay films on faces of peds and lining pores; 20 percent basalt gravel and stones; moderately alkaline (pH 8.2); gradual smooth boundary. (8 to 25 cm thick)

Bt2--41 to 48 cm; brown (10YR 4/3) gravelly silty clay loam, dark yellowish brown (10YR 3/4) moist; strong fine angular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; many roots; few very fine tubular pores; common distinct clay films on faces of peds and lining pores; 20 percent basalt gravel and stones; moderately alkaline (pH 8.2); abrupt smooth boundary. (0 to 30 cm thick)

R--48 cm; unweathered basalt; thin (less than 2 mm diameter) coats of silica and calcium carbonate on the contact surface.

TYPE LOCATION: Malheur County, Oregon; 30 feet north of east and west road, 200 feet east of large stock reservoir, in the SE 1/4 of the NW 1/4 of section 9, T. 38 S., R. 44 E.; latitude 42 degrees 17 minutes 2 seconds N and longitude 117 degrees 33 minutes 52 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: The soils are usually dry but are moist between depths of 10 to 30 cm for 60 days or more out of the 120 days following the winter solstice and are moist more than 25 percent of the time that the soil temperature is 5 degrees C or more; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 6 to 8 degrees C.
Depth to base of argillic horizon: 30 to 50 cm.
Depth to bedrock: 30 to 50 cm to a lithic contact; In some pedons the bedrock is fractured with secondary carbonates or opaline silica on the lower sides of rock fragments.
Reaction: Neutral through moderately alkaline.
Abrupt textural change: An abrupt horizon boundary is normally present between the A2 and the Bt1 horizon accompanied by an abrupt increase in clay content of between 15 and 25 percent absolute.

Particle-size control section - Clay content: 35 to 60 percent.
Rock fragments: Averages 5 to 30 percent, mainly pebbles. Lithology of fragments is volcanic rocks such as basalt.

A horizons
Value: 5 or 6 dry, 2 through 4 moist; When the upper 18 cm of the epipedon is mixed, the dry value is 6.
Chroma: 2 through 4, dry or moist.

Bt horizons
Hue: 10YR or 7.5YR.
Value: 3 through 6 dry, 3 or 4 moist.
Chroma: 2 through 6, dry or moist.
Texture: Clay, gravelly silty clay, gravelly silty clay loam, gravelly clay, gravelly clay loam, cobbly clay loam, or cobbly clay.
Clay content: 35 to 60 percent.
Consistence: Firm or very firm, moist.
Other features: Some pedons have accumulations of secondary silica as pendants on rock fragments. A Bt3 horizon is present in some pedons with calcium carbonate equivalent of 0 to 1 percent.

COMPETING SERIES: These are the Linkup and Millerlux series.

Linkup soils do not have an abrupt textural change at the top of the Bt1 horizon and have more than 20 percent sand in the argillic horizon. Millerlux soils commonly have an albic (E) horizon as part of the ochric epipedon, have slickensides in the argillic horizon, and have identifiable secondary carbonates in the lower part of the argillic horizon.

GEOGRAPHIC SETTING: Anawalt soils are on lava plains, plateaus, hills, and mountains. These soils formed in colluvium and residuum derived from volcanic rocks such as basalt with a component of loess and volcanic ash. Slopes are 0 to 50 percent. Elevations range from 1,300 to 2,000 meters in Oregon and California and up to 2,380 meters in Nevada. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 330 mm. The mean annual temperature is 4 to 7 degrees C. The mean summer temperature is 14 to 16 degrees C. and the mean winter temperature is about -3 degrees C. The frost-free period is 40 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Choptie, Oreneva, and Pearlwise soils. Choptie soils are loamy, have mollic epipedons, and do not have argillic horizons. Oreneva soils are loamy-skeletal, moderately deep to lithic contacts, and have cambic horizons. Pearlwise soils are fine-loamy, moderately deep to lithic contacts, and have thick mollic epipedons.

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

USE AND VEGETATION: Anawalt soils are used for livestock grazing and wildlife habitat. The vegetation is bluebunch wheatgrass, Idaho fescue, Sandberg's bluegrass, Thurber's needlegrass, bottlebrush squirreltail, low sagebrush, and associated forbs.

DISTRIBUTION AND EXTENT: Central and southeastern Oregon, northeastern California, and northern Nevada. These soils are extensive with over 250,000 acres of the series mapped to date. The series concept and main acreage is in MLRA 23, while other acreage occurs in MLRAs 21, 24, and 25.

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

SERIES ESTABLISHED: Lake County (Southern Part), Oregon, 1991.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 15 cm (A1 and A2 horizons).
Argillic horizon - The zone from 15 to 48 cm (Bt1 and Bt2 horizons).
Abrupt textural change - The abrupt clay increase of more than 15 percent at 15 cm (between the A2 and Bt1 horizons).
Lithic contact - The boundary at 48 cm to underlying hard, unweathered bedrock (R layer).
Particle-size control section - The zone from 15 to 48 cm (Bt1 and Bt2 horizons).

ADDITIONAL DATA: Previous authors and editors include: AON-JSC-RWL.

National Cooperative Soil Survey
U.S.A.