LOCATION SORF OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Paleargids
TYPICAL PEDON: Sorf very stony loam, range. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; light brownish gray (10YR 6/2) very stony loam, very dark grayish brown (10YR 3/2) moist; weak medium platy and very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine irregular pores and many vesicular pores in the upper part; 10 percent gravel, 10 percent cobbles and 15 percent stones; neutral (pH 6.8); abrupt smooth boundary. (3 to 6 inches thick)
2Bt--5 to 9 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; strong medium prismatic and moderate medium subangular blocky structure; extremely hard, firm, very sticky and very plastic; many very fine and fine roots; many very fine tubular pores; few faint clay films on peds; 10 percent cobbles; neutral (pH 6.8); clear smooth boundary.
2Btss--9 to 12 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist; weak medium prismatic and moderate medium subangular blocky structure; very hard, firm, very sticky and very plastic; common very fine and fine roots; many very fine tubular pores; many faint clay films on peds; few coarse slickensides; common yellowish brown and light gray weathered coarse (1 to 5 mm.) fragments; 10 percent cobbles; neutral (pH 6.9); clear smooth boundary. (Combined thickness of the 2Bt horizon is 6 to 19 inches)
2Bk1--12 to 21 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; many very fine tubular pores; strongly effervescent; common light gray lime segregations; moderately alkaline (pH 8.4); clear smooth boundary.
2Bk2--21 to 30 inches; very pale brown (10YR 7/3) clay loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few roots; many very fine pores; strongly effervescent with segregations of lime; strongly alkaline (pH 8.8). (Combined thickness of the 2Bk horizon is 3 to 20 inches)
2Crk--30 inches: calcareous tuff; violently effervescent with disseminated lime.
TYPE LOCATION: Wasco County, Oregon; about 50 feet east of road in the SW1/4 SW1/4 NE1/4 section 12, T. 7 S., R. 18 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 51 to 54 degrees F. Sorf soils are usually dry in all parts between depths of 4 and 12 inches for more than half of the time that the soil temperature exceeds 41 degrees F. The soils are neutral or slightly alkaline in the upper solum and moderately or strongly alkaline in the lower part. Rock fragments range from 35 to 60 percent in the surface horizon and 0 to 35 percent in the argillic horizon. Depth to paralithic contact is 20 to 40 inches. Hue is 10YR or 7.5YR. There is an absolute clay increase between the A and 2Bt horizon of 25 to 30 percent. The depth to secondary carbonates is 10 to 25 inches.
The A horizon has value of 4 to 6 dry, 3 or 4 moist and chroma of 2 or 3 dry or moist. It is loam with 20 to 27 percent clay, 10 to 50 percent gravel, 0 to 20 percent cobbles, and 0 to 25 percent stones.
The 2Bt and 2Btss horizons have value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 to 6 dry and moist. It is clay with 45 to 60 percent clay. It has 0 to 20 percent gravel and 0 to 10 percent cobbles. This horizon ranges from weak to strong prismatic to moderate to strong subangular blocky structure.
The 2Bk horizon has value of 5 to 7 dry, 4 or 5 moist and chroma of 3 to 6 dry and moist. It is clay loam with 27 to 40 percent clay. It has 0 to 10 percent gravel and 0 to 10 percent cobbles. In some pedons, a 2Btk horizon is present.
COMPETING SERIES: These are the Mahala, Phing, and Verdico series. Mahala soils have a mean annual soil temperature of 47 to 50 degrees F. Phing soils are over 60 inches deep. Verdico soils lack secondary carbonates and have a mean annual soil temperature averaging less than 52 degrees F.
GEOGRAPHIC SETTING: Sorf soils are on nearly level to steep side slopes at elevations of 1,200 to 2,800 feet. Slopes are 2 to 60 percent. These soils formed in mixed loess and colluvium in the upper part and old unconsolidated moderately fine and fine textured tuffaceous sediments in the lower part. The climate is characterized by cool moist winters and hot dry summers. The mean annual precipitation is 9 to 12 inches. The mean summer temperature is 63 to 66 degrees F. The mean winter temperature is 33 to 36 degrees F. The mean annual temperature is 49 to 52 degrees F. The frost-free (32 degrees F.) period is 80 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Day, Lithgow, Ridgeway and Simas soils. Day and Ridgeway soils have clay content of 60 to 70 percent, lack Bt horizons and have intersecting slickensides. Lithgow soils are moderately fine textured and have more than 35 percent rock fragments. Simas soils occur on north slopes and have mollic epipedons.
DRAINAGE AND PERMEABILITY: Well-drained; slow permeability.
USE AND VEGETATION: The principal use is livestock grazing. Native plants are antelope bitterbrush, bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass and big sagebrush.
DISTRIBUTION AND EXTENT: Central and east-central Oregon; MLRA 10. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wasco County (Trout Creek-Shaniko Area), Oregon, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Argillic horizon - from 5 to 12 inches (2Bt and 2Btss horizons)
Pale feature - increase of 15 percent or more (absolute) clay within 2.5 cm at upper boundary of argillic horizon (2Bt1 horizon)
Aridic moisture regime bordering on xeric.
Particle-size control section - 5 to 12 inches.