LOCATION DONNYBROOK OREstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic, shallow Calcidic Haploxerolls
TYPICAL PEDON: Donnybrook stony loam, range. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; grayish brown (10YR 5/2) gravelly loam, dark brown (10YR 3/3) moist; weak thin platy and moderate very fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine irregular pores; 20 percent pebbles and 5 percent stones; neutral (pH 6.6); abrupt smooth boundary. (3 to 6 inches thick)
Bw--5 to 10 inches; brown (10YR 5/3) gravelly sandy clay loam, dark brown (10YR 3/3) moist; weak to moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine tubular pores; 20 percent pebbles and 5 percent stones; neutral (pH 6.8); clear smooth boundary. (5 to 12 inches thick)
Bk--10 to 18 inches; (10YR 5/3) gravelly sandy clay loam, dark brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine tubular pores; 20 percent pebbles and 5 percent stones; strongly calcareous; moderately alkaline (pH 8.0); abrupt wavy boundary. (4 to 10 inches thick)
2C--18 to 28 inches; light brownish gray (10YR 6/2) slightly weathered coarse grained tuff, dark yellowish brown (10YR 4/4) moist.
TYPE LOCATION: Jefferson County, Oregon; 2,310 feet north, 45 feet west of the SE corner (300 feet north of gravel road) section 31, T. 9 S., R. 17 E.
RANGE IN CHARACTERISTICS: The soils are dry between depths of 4 and 12 inches for more than half the time (cumulative) that the soil temperature at 20 inches is above 41 degrees F., and are dry between depths of 4 and 12 inches during the summer months for 60 consecutive days in most years. The mean annual soil temperature ranges from 47 to 53 degrees F. Depth to a paralithic contact is 12 to 20 inches. Free lime occurs at depths of 10 to 18 inches. The mollic epipedon is 7 to 10 inches thick. The amount of rock fragments range from 20 to about 35 percent. Amount of fragments larger than 3 inches ranges from 0 to 10 percent.
The A horizon has chroma of 2 or 3 moist and dry.
The Bw horizon has value of 5 or 6 dry and 3 or 4 moist. It ranges from heavy loam and clay loam to sandy clay loam with 18 to 30 percent clay and more than 15 percent fragments coarser than very fine sand.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Donnybrook soils are at elevations of 2,500 to 4,000 feet on south-facing sloping to steep upland with slope gradients ranging from 10 to 60 percent. These soils formed in shallow medium and moderately fine textured colluvium over siltstone, sandstone, conglomerate and tuffaceous materials. Mean annual precipitation is 11 to 14 inches, mean annual temperature is 44 to 51 degrees F., mean summer temperature is 61 to 64 degrees F., and mean winter temperature is 30 to 35 degrees F. The average frost-free (32 degrees F.) period is 60 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Degner and Tub soils. Degner soils are deeper than 40 inches to bedrock and have very gravelly clayey argillic horizons. Tub soils have clayey argillic horizons and are deeper than 20 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for dryland cropping, range, wildlife and water supply purposes. Native plants are grasses, forbs, shrubs and juniper.
DISTRIBUTION AND EXTENT: Central Oregon. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jefferson County (Trout Creek-Shaniko Area), Oregon, 1970.
REMARKS: These soils were formerly classified as Chestnut soils.
NSTH 17, RECLASSIFICATION ONLY, 3/95