LOCATION FOPIANO OREstablished Series
TAXONOMIC CLASS: Clayey, smectitic, frigid, shallow Vitrandic Argixerolls
TYPICAL PEDON: Fopiano ashy silty clay loam, rangeland. (Colors are for moist soil unless otherwise noted.)
A1--0 to 3 inches; very dark brown (10YR 2/2) ashy silty clay loam, grayish brown (10YR 5/2) dry; weak thin platy and weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; neutral (pH 6.8); clear smooth boundary. (2 to 6 inches thick)
A2--3 to 8 inches; black (10YR 2/1) ashy silty clay loam, dark grayish brown (10YR 4/2) dry; weak fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine roots; many very fine tubular pores; neutral (pH 6.8); clear wavy boundary. (3 to 7 inches thick)
2Bt--8 to 15 inches; dark brown (10YR 3/3) clay, yellowish brown (10YR 5/4) dry; weak fine and medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; many distinct clay films; 5 to 10 percent strongly weathered tuff gravel; neutral (pH 7.0); clear irregular boundary. (5 to 11 inches thick)
2Cr--15 to 25 inches; partially consolidated brown volcanic tuff; continuous and coherent but can be dug with a spade.
TYPE LOCATION: Wheeler County, Oregon; 13 miles east of Mitchell on U.S. Highway 26, 0.8 miles south on Derr Meadow Road, 50 feet east of road in E1/2 NE1/4 SW1/4 section 23, T.12S., R.23E.
RANGE IN CHARACTERISTICS: Fopiano soils are usually moist but are dry in all parts at depths from 4 inches to the paralithic contact for 60 to 80 consecutive days in most years. The mean annual soil temperature is 43 to 47 degrees F. Depth to a paralithic contact is 10 to 20 inches. Hue throughout the soil is 10YR or 7.5YR. Unweathered rock fragments throughout the solum range from 0 to 20 percent. They are stones, cobbles and pebbles and commonly are basaltic. Mollic epipedon is 7 to 15 inches thick.
The A horizon has value of 4 or 5 dry and chroma of 1 or 2. It is ashy silty clay loam or ashy clay loam with 27 to 35 percent clay. It has 5 to 15 percent glass and acid oxalate extractable plus one-half the iron is 0.3 to 0.5 percent.
The Bt horizon has value of 4 or 5 dry, 2 or 3 moist and chroma of 2 through 4 moist and dry. It has weak to strong blocky or subangular blocky structure. It has strong, coarse prismatic structure in some pedons. It is clay with 40 to 50 percent clay.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Fopiano soils are on benches and hills at elevations ranging from 3,400 to 5,000 feet. The soils formed in colluvium from tuff and old sediments with some influence from loess. The climate is semiarid and has a mean annual precipitation of 13 to 16 inches. The mean annual temperature is 41 to 45 degrees F.; the mean summer temperature is about 62 degrees F.; and the mean January temperature is 28 degrees F. The frost free period ranges from 30 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anatone, Calabar, Marsden and Snell soils. Anatone soils are less than 20 inches deep to a lithic contact and are skeletal. Calabar soils are on fans and terraces, are deeper than 40 inches to bedrock and have silty clay loam natric horizons. Marsden soils are deeper than 40 inches to bedrock. Snell soils are clayey, skeletal and are 20 to 40 inches deep to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: Mainly range. Native vegetation is Idaho fescue and low sagebrush.
DISTRIBUTION AND EXTENT: Eastern-central Oregon, MLRA 10. The soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grant County, Oregon, 1975.
REMARKS: Diagnostic horizons and other features:
Mollic epipedon - 0 to 15 inches
Argillic horizon - 8 to 15 inches
ADDITIONAL DATA: S97OR-023-013.