LOCATION COUGHANOUR OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Argiduridic Durixerolls
TYPICAL PEDON: Coughanour silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
A11--0 to 3 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; common fine roots; many fine tubular pores; neutral (pH 7.0); clear smooth boundary. (2 to 4 inches thick)
A12--3 to 10 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak medium subangular blocky structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; common fine roots; common fine and few medium tubular pores; neutral (pH 7.2); clear wavy boundary. (4 to 8 inches thick)
A3--10 to 18 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few fine roots; common fine and common medium tubular pores; mildly alkaline (pH 7.4); clear wavy boundary. (0 to 9 inches thick)
B21t--18 to 26 inches; dark yellowish brown (10YR 4/4) silty clay loam, yellowish brown (10YR 5/4) dry; strong medium subangular blocky structure; slightly hard, friable, sticky and plastic; few fine roots; common fine tubular pores; common thin clay films; mildly alkaline (pH 7.4); clear wavy boundary. (5 to 10 inches thick)
B22tca--26 to 32 inches; dark brown (7.5YR 4/4) silty clay loam, yellowish brown (10YR 5/4) dry; strong medium subangular blocky structure; hard, firm, sticky and plastic; few fine roots; few fine tubular pores; common moderately thick clay films; few lime splotches; slightly effervescent in matrix; moderately alkaline (pH 8.0); abrupt wavy boundary. (5 to 9 inches thick)
C1casim--32 to 40 inches; strongly cemented platy silica-lime hardpan with indurated laminar capping on the plates. (6 to 20 inches thick)
C2--40 to 60 inches; dark brown (7.5YR 4/4) sandy loam, yellowish brown (10YR 5/4) dry; massive; slightly hard, friable, nonsticky and nonplastic; few fine tubular pores; 10 percent pebbles; 5 percent cobbles, moderately alkaline (pH 8.0).
TYPE LOCATION: Union County, Oregon; 2 miles west of town of North Powder in the northwest corner of NE1/4 section 20, T.6S., R.39E.
RANGE IN CHARACTERISTICS: Depth to a duripan ranges from 20 to 40 inches. These soils are dry in all parts of the moisture control section for more than half the time (cumulative), unless irrigated. Mean annual soil temperature is 47 degrees to 52 degrees F.
The A horizon has value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 or 3 moist or dry. The mollic epipedon is 10 to 20 inches thick.
The B horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist and chroma of 3 or 4 moist and dry. It is heavy silt loam or silty clay loam and averages 24 to 34 percent clay.
The C2 horizon has hue of 7.5YR or 10YR. It averages 0 to 20 percent cobbles and 0 to 40 percent pebbles.
COMPETING SERIES: This is Selah series in another family. Selah soils have more than 15 percent particle coarser than very fine sand.
GEOGRAPHIC SETTING: Coughanour soils are on alluvial fans and low terraces at elevations of 2,700 to 3,500 feet. Slopes are 0 to 12 percent. The soils formed in old alluvium mainly from volcanic ash and loess. The climate is semiarid and the summers are dry. The mean annual temperature ranges from 45 degrees to 50 degrees F. The average frost-free season is 110 to 140 days. Average annual precipitation is 9 to 13 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hutchinson, Ladd, and Virtue soils. Hutchinson soils have a fine textured argillic horizon. Ladd soils lack a duripan and Virtue soils have an ochric epipedon.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; very slow permeability through the duripan.
USE AND VEGETATION: Irrigated alfalfa, pasture and small grain. The native vegetation dominantly is bluebunch wheatgrass, Idaho fescue and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: Union County, Oregon. The soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Union County, Oregon, 1978.
NSTH 17, RECLASSIFICATION ONLY, 3/95