LOCATION DOWDE OR

Established Series
Rev. RTS/TDT
06/2011

DOWDE SERIES

The Dowde series consists of deep, well drained soils that formed in colluvium. Dowde soils are on uplands and have slopes of 30 to 90 percent. The mean annual precipitation is about 65 inches and the mean annual air temperature is about 50 degrees F.

TAXONOMIC CLASS: Fine-silty, isotic, mesic Humic Dystrudepts

TYPICAL PEDON: Dowde silt loam, wooded. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 3 inches; slightly decomposed litter of leaves, twigs, moss and woody materials.

A--3 to 8 inches; dark reddish brown (5YR 3/3) silt loam, brown (7.5YR 5/4) dry; moderate very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots and few, medium and coarse roots; many very fine irregular pores; 10 percent very fine gravel; slightly acid; clear smooth boundary. (5 to 9 inches thick)

Bw1--8 to 22 inches; reddish brown (5YR 4/3) silt loam, light brown (7.5YR 6/4) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots and few medium roots; many very fine tubular pores; 5 percent very fine gravel; moderately acid; gradual wavy boundary. (12 to 18 inches thick)

Bw2--22 to 40 inches; reddish brown (5YR 4/3) silt loam, light brown (7.5YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots and few medium roots; many very fine tubular pores; 3 percent very fine gravel; moderately acid; gradual wavy boundary. (14 to 20 inches thick)

Bw3--40 to 57 inches; reddish brown (5YR 4/4) silt loam, light brown (7.5YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and very fine roots; many very fine tubular pores; 5 percent very fine gravel and 2 percent vesicular basalt cobbles; very strongly acid; gradual wavy boundary. (14 to 20 inches thick)

C--57 to 63 inches; reddish brown (5YR 4/4) gravelly silty clay loam, brown (7.5YR 5/4) dry; massive; slightly hard, friable, moderately sticky and moderately plastic; 20 percent gravel and 10 percent vesicular basalt cobbles; very strongly acid.

TYPE LOCATION: Columbia County, Oregon; 100 feet east of the North Fork Scappoose Creek-Quarry Road, SE1/4 NE1/4 NW1/4 section 28, T. 4 N., R. 2 W.

RANGE IN CHARACTERISTICS: The soil is usually moist and is dry for a short period of less than 45 consecutive days between depths of 4 to 12 inches. The mean annual soil temperature is 47 to 54 degrees F. The texture of the control section is silt loam or loam. It has an average of 18 to 27 percent clay and less than 15 percent of the particles are fine sand or coarser including fragments up to 7.5 centimeters in diameter.

The A horizon has value of 2 or 3 moist and 4 or 5 dry. Chroma is 2 or 3 moist and 3 or 4 dry. Hue is 7.5YR or 5YR. It averages 12 to 18 percent clay and 5 to 10 percent very fine gravel. Range of pH is 5.6 to 6.5.

The B horizons have value of 5 or 6 dry, 4 or 5 moist and chroma of 3 or 4 moist and dry. Hue is 7.5YR or 5YR. It averages 18 to 27 percent clay and 5 or 10 percent very fine gravel. Range of pH is 5.6 to 6.5.

The C horizon has value of 5 or 6 dry, 4 or 5 moist and chroma of 4, 5, or 6 moist and dry. It has 0 to 15 percent cobbles and 5 to 30 percent gravel. Range of pH is 4.5 to 5.5.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Dowde soils are on uplands in the Coast Range at elevations of 300 to 1,500 feet. Slopes range from 30 to 90 percent. The soils formed in colluvium. The underlying bedrock is basalt. The mean annual precipitation is 50 to 70 inches. The mean July temperature is 60 to 63 degrees F., mean January temperature is 35 to 37 degrees F., mean annual temperature is 45 to 50 degrees F. The frost-free period is 100 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alstony, Bacona and Honeygrove soils. Alstony soils are medial-skeletal. Bacona and Honeygrove soils have argillic horizons.

DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.

USE AND VEGETATION: These soils are used for timber production, recreation and wildlife habitat. Native vegetation is Douglas-fir, bigleaf maple, vine maple, salal, cascade Oregon-grape, rose and swordfern.

DISTRIBUTION AND EXTENT: Mountainous uplands of the Coast Range in Columbia County, Oregon; MLRA 1. This series is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Columbia County, Oregon, 1980.

REMARKS: Diagnostic horizons and other features;
Ochric epipedon
Humic subgroup - color requirement is met when the upper 7 inches of the mineral soil is mixed
Cambic horizon - from 8 to 57 inches

National Cooperative Soil Survey
U.S.A.