LOCATION WATAMA OR+IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Pachic Haploxerolls
TYPICAL PEDON: Watama silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 4 inches; very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; neutral (pH 6.6); abrupt smooth boundary.
A--4 to 10 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; neutral (pH 6.6); clear smooth boundary. (Combined thickness of the A horizon is 6 to 15 inches)
BA--10 to 17 inches; dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; neutral (pH 6.8); clear smooth boundary. (0 to 12 inches thick)
Bw1--17 to 24 inches; dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; common very dark grayish brown (10YR 3/2) coatings on peds; weak coarse prismatic and moderate medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; 2 percent cobbles; neutral (pH 6.8); clear smooth boundary.
Bw2--24 to 34 inches; brown (10YR 4/3) clay loam, pale brown (10YR 6/3) dry; common dark brown (10YR 3/3) coatings on peds; weak medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; 2 percent cobbles; neutral (pH 6.8); clear smooth boundary. (Combined thickness of the Bw horizon is 4 to 27 inches)
2R--34 inches; basalt bedrock.
TYPE LOCATION: Wasco County, Oregon; 75 feet south of county road in the NE1/4 NW1/4 NE1/4 section 16, T. 5 S., R. 12 E.
RANGE IN CHARACTERISTICS: In most years the soils are usually moist but are dry between depths of 4 and 12 inches for more than 60 consecutive days within the 4-month period following the summer solstice. The mean annual soil temperature is 47 to 54 degrees F. The thickness of the solum and depth to bedrock is 20 to 40 inches. The mollic epipedon is 20 to 34 inches thick and includes all or part of the Bw horizon. Hue is 10YR or 7.5YR throughout.
The A horizon has value of 1 to 3 moist, 4 or 5 dry and chroma of 2 or 3 moist and dry. It is silt loam, loam or gravelly silt loam with 0 to 20 percent gravel.
The Bw horizon has value of 2 to 4 moist, 4 to 6 dry and chroma of 2 to 4 moist and dry. It is loam, silt loam, gravelly silt loam, clay loam or silty clay loam and averages 18 to 35 percent clay. It has 0 to 25 percent gravel and 0 to 5 percent cobbles. It is neutral to moderately alkaline.
COMPETING SERIES: These are the Alicel, Anaverde, Calimus, Chalkford, Linville, Sinamox, and Sweeney series. Alicel, Anaverde, Calimus, Chalkford, Sinamox, and Sweeney soils are deeper than 40 inches to bedrock. Linville soils have 15 to 35 percent rock fragments in the B2 horizon.
GEOGRAPHIC SETTING: Watama soils are on ridges and plateaus. Slopes are 0 to 35 percent. Elevations are 1,000 to 4,000 feet. The soils formed in reworked loess and volcanic ash and colluvium weathered from basalt. The climate is characterized by cool wet winters and hot dry summers. The mean annual precipitation is 12 to 24 inches. The mean summer temperature is 64 degrees F. The mean winter temperature is 30 degrees F. The mean annual temperature is 45 to 52 degrees F. The frost-free period (32 degrees F.) is 100 to 170 days and for (28 degrees F.) it is 170 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bakeoven and Wapinitia soils. Bakeoven soils are less than 12 inches deep to bedrock and contain more than 50 percent fragments coarser than 2 mm. Wapinitia soils are 40 to 60 inches to bedrock and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: These soils are used mainly for production of grain crops. Other uses are hay and pasture and livestock grazing. Potential native vegetation is mainly bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass and related forbs.
DISTRIBUTION AND EXTENT: Central and northeastern Oregon, and north-central Idaho; MLRA 8, 9, 10. The soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wasco County, Oregon, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
mollic (pachic) epipedon - from the surface to 24 inches (Ap, A, BA, and Bw1 horizons)
cambic horizon - from 24 to 34 inches (Bw2 horizon)
lithic contact - bedrock at 34 inches
particle-size control section - from 10 to 34 inches (BA, Bw1, and Bw2 horizons)