LOCATION WRENTHAM OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Pachic Haploxerolls
TYPICAL PEDON: Wrentham silt loam, range. (Colors are for moist soil unless otherwise noted.)
A1--0 to 5 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; weak thin and medium platy and weak very fine granular structure; soft, friable, slightly sticky and slightly plastic; many roots; few very fine and fine irregular pores; 5 percent gravel; neutral (pH 6.6); clear smooth boundary. (2 to 8 inches thick)
A2--5 to 12 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; weak coarse prismatic and weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; common very fine tubular pores; 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (5 to 10 inches thick)
AB--12 to 18 inches; dark brown (10YR 3/3) gravelly silt loam, brown (10YR 5/3) dry; weak medium prismatic and weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; common very fine tubular pores; thin slightly darker colored coatings on surfaces of peds; 20 percent basaltic gravel; neutral (pH 7.0); gradual smooth boundary. (0 to 10 inches thick)
Bw--18 to 32 inches; dark brown (10YR 3/3) very cobbly silt loam, yellowish brown (10YR 5/4) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, sticky and plastic; common roots; common very fine tubular pores; thin darker colored coatings on surfaces of peds; 40 percent angular cobbles and 20 percent gravel; neutral (pH 7.0); abrupt wavy boundary. (7 to 30 inches thick)
2R--32 inches; basalt.
TYPE LOCATION: Sherman County, Oregon; SW1/4 NE1/4 NW1/4 SE1/4 of sec. 10, T. 3 S., R. 15 E.
RANGE IN CHARACTERISTICS: Wrentham soils are usually moist, but are continuously dry for 70 to 90 days each year between depths of 4 and 12 inches during the 3-month period following the summer solstice. The mean annual soil temperature is 47 to 54 degrees F. The soil is 20 to 40 inches deep to basalt. The mollic epipedon ranges from 20 to 36 inches thick.
The A horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 1 or 2 moist and dry. It contains 0 to 15 percent gravel and 0 to 10 percent cobbles. The percentage of rock-exposed surface ranges from 2 to 15 percent. It has weak platy or subangular blocky structure. It is slightly acid or neutral.
The Bw horizon has value of 3 or 4 moist, 4 or 5 dry and chroma of 2 through 4 moist and 3 or 4 dry. The moist value and chroma of 4 occur below depth of 20 inches. The Bw horizon is silt loam, or silty clay loam and contains 20 to 60 percent cobbles and 5 to 50 percent gravel. Its structure is weak or moderate subangular blocky.
COMPETING SERIES: These are the Dehlinger, Drit, Gamboa, Langrell and Packard series. All of the above soils have bedrock at depths greater than 40 inches.
GEOGRAPHIC SETTING: The Wrentham soils are on north-facing canyon slopes at 900 to 3,600 feet elevation. Slopes are 35 to 70 percent. They formed in loess mixed with some basalt colluvium. The climate is semiarid with cool, moist winters and warm, dry summers. Mean winter temperature is 33 to 35 degrees F., mean summer temperature is 62 to 64 degrees F., mean annual temperature is 45 to 52 degrees F. The mean annual precipitation is 10 to 16 inches. The frost-free period is 60 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anderly, Bakeoven, Cantala, Condon, Lickskillet and Morrow soils. Anderly, Cantala, Condon and Morrow soils are on gently sloping to moderately steep uplands and lack rock fragments. Bakeoven and Lickskillet soils are less than 20 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well-drained; rapid runoff; moderately slow permeability.
USE AND VEGETATION: The soils are used for range. The vegetation is Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass, forbs and shrubs.
DISTRIBUTION AND EXTENT: North-central Oregon. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Sherman County, Oregon, 1961.