LOCATION SEHARNEY                OR

Established Series
Rev. MPK-TDT-JVC-JBF
06/2011

SEHARNEY SERIES

The Seharney series consists of shallow to a duripan, well drained soils that formed in residuum derived from basalt or andesite with a mixture of loess. Seharney soils are on plateaus and hills. Slopes are 3 to 20 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid, shallow Xereptic Haplodurids

TYPICAL PEDON: Seharney cobbly silt loam--at an elevation of 1,436 meters--rangeland. (Colors are for dry soil unless otherwise noted. When described on August 9, 1984 the soil was dry.)

A1--0 to 5 cm; light gray (10YR 7/2) cobbly silt loam, brown (10YR 4/3) moist; weak medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots; many very fine and fine irregular pores; 10 percent gravel and 15 percent cobbles; neutral (pH 7.0); abrupt smooth boundary.

A2--5 to 13 cm; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots; many very fine and fine irregular pores; 5 percent gravel; neutral (pH 7.2); clear wavy boundary. (Combined thickness of the A horizons is 8 to 18 cm.)

Bw--13 to 28 cm; pale brown (10YR 6/3) cobbly silt loam, brown (10YR 4/3) moist; moderate coarse subangular blocky structure parting to moderate medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; many fine, and common medium roots; many very fine and fine irregular pores; 5 percent gravel and 15 percent cobbles; slightly alkaline (pH 7.4); clear wavy boundary. (15 to 20 cm thick)

Bq--28 to 43 cm; very pale brown (10YR 7/3) very cobbly silt loam, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common medium roots; common fine irregular pores; 10 percent durinodes; 5 percent gravel, 30 percent cobbles and 5 percent stones; slightly alkaline (pH 7.7); abrupt wavy boundary. (0 to 15 cm thick)

Bkqm--43 to 61 cm; very pale brown (10YR 8/3) cemented material, light yellowish brown (10YR 6/4) moist; massive with fractures; extremely hard and brittle; strongly cemented by opaline silica; strongly effervescent with disseminated lime throughout the matrix; 5 percent gravel and 40 percent cobbles; moderately alkaline (pH 8.4); clear wavy boundary. (5 to 25 cm thick)

2R--61 cm; fractured basalt.

TYPE LOCATION: Harney County, Oregon; about 2,300 feet south and 2,100 feet east of the northwest corner of section 15, T. 28 S., R. 30 E.; USGS Coyote Buttes 7.5 minute topographic quadrangle; latitude 43 degrees 08 minutes 25 seconds N and longitude 118 degrees 59 minutes 19 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in summer and fall; the moisture control section is dry for one-half to three-fourths of the time when the soil temperature is above 5 degrees C; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Depth to base of cambic horizon: 25 to 50 cm.
Depth to strongly cemented duripan: 25 to 50 cm.
Depth to bedrock: 33 to 76 cm to a lithic contact.

Particle-size control section - Clay content: Averages 18 to 27 percent.
Sand content: 15 to 40 percent.
Rock fragments: 35 to 50 percent, mainly cobbles. Lithology of fragments are volcanic rocks such as basalt and andesite.

A horizons
Value: 6 or 7 dry, 3 through 5 moist.
Chroma: 2 or 3 dry, 3 or 4 moist.

Bw horizon and Bq horizon (when present)
Value: 5 through 8 dry, 3 through 6 moist.
Chroma: 2 or 3 dry, 3 or 4 moist
Texture: Cobbly silt loam, very cobbly silt loam, very stony sandy loam, or very cobbly loam.
Clay content: 18 to 27 percent.
Rock fragments: 20 to 50 percent.
Reaction: Neutral or slightly alkaline.
Other features: Pedons with Bq horizons have up to 20 percent durinodes.

Bkqm horizon
Value: 6 through 8 dry, 5 or 6 moist.
Chroma: 3 through 6, dry or moist.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Seharney soils are on plateaus and hills. These soils formed in colluvium and residuum derived from basalt or andesite with a mixture of loess. Slopes are 2 to 20 percent. Elevations range from 1280 to 1,610 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 6 to 7 degrees C, and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Middlebox and Morganhills soils. These soils are ashy and do not have duripans.

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

USE AND VEGETATION: Seharney soils are used for livestock grazing and wildlife habitat. The potential native vegetation is Wyoming big sagebrush, Thurber's needlegrass, Indian ricegrass, and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are moderately extensive. MLRA 23.

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

SERIES ESTABLISHED: Harney County, Oregon, 1997.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1 and A2 horizons and part of the Bw horizon).
Cambic horizon - The zone from 13 to 43 cm (Bw and Bq horizons).
Durinodes - The zone from 28 to 43 cm (Bq horizon).
Duripan - The zone from 43 to 61 cm (Bkqm horizon).
Lithic contact - The boundary at 61 cm to underlying hard, unweathered bedrock (2R layer).
Particle-size control section - The zone from 25 to 43 cm (Bq horizon and part of the Bw horizon).

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National Cooperative Soil Survey
U.S.A.