LOCATION RAZ OR

Established Series
Rev. JVC/JBF
05/2011

RAZ SERIES

The Raz series consists of shallow to a duripan, well drained soils that formed in slope alluvium, colluvium and residuum derived from basalt and tuff. Raz soils are on lava plateaus. Slopes are 1 to 20 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy, mixed, superactive, frigid, shallow Xeric Haplodurids

TYPICAL PEDON: Raz very cobbly loam--on a 6 percent slope--rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 5 cm; pale brown (10YR 6/3) very cobbly loam, dark brown (10YR 3/3) moist; moderate very thick platy structure; soft, very friable, slightly sticky and slightly plastic; few fine and very fine roots; many fine vesicular pores and few fine tubular; 20 percent cobbles and 15 percent gravel; slightly alkaline (pH 7.6); clear smooth boundary. (3 to 10 cm thick)

Bk--5 to 18 cm; light gray (10YR 7/2) gravelly clay loam, brown (10YR 4/3) moist; weak thick platy structure; slightly hard, firm, moderately sticky and moderately plastic; few fine and very fine roots; many very fine vesicular pores and few very fine tubular; slightly effervescent; secondary carbonates segregated in few fine masses; 5 percent cobbles and 10 percent gravel; slightly alkaline (pH 7.8); clear wavy boundary. (8 to 25 cm thick)

Bkq--18 to 30 cm; light gray (10YR 7/2) clay loam, yellowish brown (10YR 5/4) moist; massive; hard, firm and brittle, moderately sticky and moderately plastic; few fine roots; few fine tubular pores; strongly effervescent; secondary carbonates finely disseminated in the matrix; 5 percent gravel; horizon is discontinuously brittle; moderately alkaline (pH 8.2); clear wavy boundary. (8 to 20 cm thick)

Bkqm--30 to 58 cm; cemented material; moderate very thick platy structure; indurated by opaline silica; violently effervescent; secondary carbonates segregated in common coats on plates; opal pendants on bottoms of plates; abrupt smooth boundary. (8 to 46 cm thick)

2R--58 cm; basalt.

TYPE LOCATION: Harney County, Oregon; in the Basque Hills about 1.5 miles west of Catlow Rim and 0.75 miles northwest of Raz Lewis Flat; approximately 500 feet north and 2,500 feet west of the southeast corner of section 15, T. 38 S., R. 32 E.; USGS Square Mountain 7.5 minute topographic quadrangle; latitude 42 degrees 16 minutes 08 seconds N and longitude 118 degrees 56 minutes 35 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry in all parts of the moisture control section for more than half the time when the soil temperature is greater than 5 degrees C. The soil temperature is above 5 degrees C from mid-April through mid-November; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mean summer soil temperature: 15 to 17 degrees C.
Depth to duripan: 25 to 46 cm.
Depth to bedrock: 50 to 100 cm to a lithic contact; typically is less than 76 cm.

Particle-size control section - Clay content: Averages 20 to 35 percent.
Rock fragments: 5 to 25 percent, mainly gravel and cobbles concentrated in the upper part of the control section. Lithology of fragments are volcanic rocks such as basalt and tuff.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.

Bk horizon or Bw horizon (when present)
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 through 6 dry, 3 through 6 moist.
Texture: Gravelly clay loam, gravelly loam, cobbly clay loam, loam, sandy clay loam, or clay loam.
Clay content: 20 to 35 percent.
Rock fragments: 5 to 25 percent.
Identifiable secondary carbonates: When present occurs as masses in the matrix or on rock fragments.
Calcium carbonate equivalent: 0 to 2 percent.
Reaction: Slightly alkaline or moderately alkaline.
Other features: This horizon qualifies as a cambic horizon when 6 inches or more thick.

Bkq horizon or Bq horizon (when present)
Value: 6 or 7 dry, 4 through 6 moist.
Chroma: 2 through 6 dry, 3 through 6 moist.
Texture: Gravelly clay loam, gravelly loam, cobbly clay loam, loam, sandy loam, sandy clay loam, or clay loam.
Clay content: 18 to 35 percent.
Rock fragments: 5 to 25 percent.
Identifiable secondary carbonates: When present occurs as masses on rock fragments or finely disseminated in the matrix.
Calcium carbonate equivalent: 0 to 3 percent.

COMPETING SERIES: These are the Nouque, Umil, and Weigle series.

Nouque and Umil soils do not have lithic contacts below the duripan. Weigle soils average 8 to 18 percent clay in the particle-size control section and have lithic contacts at depths of 38 to 50 cm.

GEOGRAPHIC SETTING: Raz soils are on lava plateaus. They typically occur on summit positions. These soils formed in slope alluvium, colluvium, and residuum derived from basalt and tuff. Slopes are 1 to 20 percent. Elevations range from 1,250 to 2,075 meters. The climate is semiarid and characterized by cold, moist winters and warm, dry summers. The mean annual precipitation is 200 to 300 mm, the mean annual temperature is 4 to 7 degrees C, and the frost-free period is 50 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: This is the Brace soil. Brace soils have argillic horizons and are moderately deep to indurated duripans.

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

USE AND VEGETATION: Raz soils are used for livestock grazing. The vegetation is Wyoming big sagebrush, bluebunch wheatgrass, Thurber's needlegrass, bottlebrush squirreltail, and Indian ricegrass.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are extensive with about 400,000 acres of the series mapped to date. MLRA 23.

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 18 cm (A and Bk horizons).
Identifiable secondary carbonates - The zone from 5 to 58 cm (Bk, Bkq, and Bkqm horizons).
Duripan - The zone from 30 to 58 cm (Bkqm horizon).
Lithic contact - The boundary at 58 cm to underlying hard, unweathered bedrock (2R layer).
Particle-size control section - The zone from the soil surface to 30 cm (A, Bk, and Bkq horizons).

ADDITIONAL DATA: Previous authors and editors include CFL-TDT-TM.

National Cooperative Soil Survey
U.S.A.