LOCATION DOLASON                 CA

Established Series
Rev: JHP/JPS/KP
07/2016

DOLASON SERIES

The Dolason series consists of very deep, well drained soils formed in colluvium and residuum derived from siltstone, mudstone, and sandstone. Dolason soils are on mountains and have slopes of 9 to 75 percent. The mean annual precipitation is about 2290 millimeters (90 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Pachic Humixerepts

TYPICAL PEDON: Dolason loam - on a convex, southwest-facing slope of 15 percent under annual and perennial grasses and forbs at 915 meters (3200 feet) elevation. (Colors are for dry soil unless otherwise stated. When described on October 31, 2002, the soil was dry throughout.)

A1--0 to 16 centimeters (0 to 6 inches); dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak medium granular and weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; common very fine and fine irregular and tubular pores; 5 percent gravel; strongly acid (pH 5.2); gradual wavy boundary.

A2--16 to 44 centimeters (6 to 17 inches); dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak fine and medium subangular blocky structure; soft, friable, nonsticky and nonplastic; common very fine and fine roots; common very fine and fine tubular pores; 5 percent gravel; strongly acid (pH 5.4); gradual wavy boundary.

A3--44 to 68 centimeters (17 to 27 inches); grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; 8 percent gravel; strongly acid (pH 5.2); gradual wavy boundary.

A4--68 to 89 centimeters (27 to 35 inches); dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; few very fine and fine tubular pores; 10 percent gravel; very strongly acid (pH 5.0); clear wavy boundary. (Combined thickness of the A1, A2 & A3 horizons is 50 to 100 centimeters)

Bw1--89 to 130 centimeters (35 to 51 inches); yellow (2.5Y 7/6) gravelly loam, yellowish brown (10YR 5/6) moist; moderate medium subangular structure; slightly hard, friable, slightly sticky and moderately plastic; few very fine and fine roots; few very fine, fine and medium tubular pores; 30 percent gravel and 1 percent cobbles; strongly acid (pH 5.2); gradual wavy boundary.

Bw2--130 to 150 centimeters (51 to 59 inches); yellow (2.5Y 7/6) gravelly loam, yellowish brown (10YR 5/6) moist; weak medium and coarse subangular structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and tubular pores; 30 percent gravel; strongly acid (pH 5.4); gradual wavy boundary. (Combined thickness of Bw1 and Bw2 is 0 to 100 centimeters)

BC--150 to 165 centimeters (59 to 65 inches); pale yellow (2.5Y 7/4) gravelly loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine and interstitial pores; 15 percent gravel; strongly acid (pH 5.4); gradual wavy boundary. (0 to 40 centimeters thick)

C--165 to 195 centimeters (65 to 77 inches); pale yellow (2.5Y 7/4) very gravelly sandy loam, yellowish brown (10YR 5/6) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine and interstitial pores; 35 percent gravel; strongly acid (pH 5.4).

TYPE LOCATION: Trail Ridge, Humboldt County, California; located in Trail Ridge Prairie, section 5, T. 8 N., R. 3 E., WGS84 Decimal degrees 41.1099444 latitude and -123.8512778 longitude; HBLM; USGS Hupa Mountain Quadrangle. UTM Zone 10 428525mE, 4551310mN; NAD83.

RANGE IN CHARACTERISTICS:

Soil Moisture: The soil is dry in all parts in the moisture control section from about July 10 to September 20, and is moist in all parts from about October 1 to June 1. The soils have a xeric moisture regime.

Soil Temperature: The mean annual soil temperature is 10 to 15 degrees C (50 to 59 degrees F). The difference between mean summer and mean winter temperature is 6 to 10 degrees C. The soils have a mesic soil temperature regime.

Umbric epipedon: 50 to 100 centimeters thick

Reaction: very strongly through moderately acid, and base saturation, by ammonium acetate, is less than 60 percent.

Surface fragments: 0 to 12 percent gravel and 0 to 3 percent cobble

Particle-Size Control Section (weighted average):

Rock fragments: 5 to 35 percent gravel and 0 to 10 percent cobbles.
Clay content: 18 to 25 percent clay.

A horizon

Hue: 10YR or 2.5Y.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 through 3 dry, 1 through 3 moist.

Texture of fine earth: loam or sandy clay loam.
Rock fragments: 3 to 34 percent gravel and 0 to 10 percent cobbles.
Clay content: 15 to 27 percent clay.

Bw horizon

Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 5 or 6 moist.
Chroma: 3 through 6 dry, 4 or 6 moist.

Texture of fine earth: coarse sandy loam, sandy loam, loam, sandy clay loam, or clay loam.
Rock fragments: 3 to 59 percent gravel and 0 to 10 percent cobbles.
Pararock fragments: 0 to 50 percent paragravel.
Clay content: 18 to 32 percent clay.

C horizon

Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 4 through 6 moist.
Chroma: 3 through 6 dry, 4 or 6 moist.

Texture of fine earth: coarse sandy loam, sandy loam, loam, sandy clay loam, or clay loam.
Rock fragments: 10 to 59 percent gravel and 0 to 10 percent cobbles.
Pararock fragments: 0 to 50 percent paragravel.
Clay content: 15 to 30 percent clay.

COMPETING SERIES: These are the Countshill and Doty series. The Countshill soils are 50 to 100 centimeters deep to soft bedrock. Doty soils have a difference between mean July and mean January soil temperatures of 12 to 18 degrees C.

GEOGRAPHIC SETTING: Dolason soils are on mountain slopes and ridges. Slopes are 9 to 50 percent. Elevations are 153 to 1032 meters (0 to 3390 feet). The soils formed in colluvium and residuum derived from siltstone, mudstone, and sandstone. The climate is humid with cool, foggy summers and cool, rainy winters. Mean annual precipitation is 1270 to 2550 millimeters (60 to 100 inches). Mean January temperature is about 7 degrees C; mean July temperature is about 15 degree C; and the mean annual temperature is 10 to 15 degree C (50 to 59 degrees F). Frost free season is about 200 to 280 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Airstrip, Countshill and Elkcamp soils. Airstrip soils are loamy-skeletal and 50 to 102 centimeters (20 to 40 inches) deep to a lithic contact. Countshill soils are 50 to 102 centimeters (20 to 40 inches) deep to a paralithic contact. Elkcamp soils have an argillic horizon and have redoximorphic features between the depths of 75 and 152 centimeters (30 to 60 inches). The Airstrip and Countshill soils are on ridgecrests and spur ridges. The Elkcamp soils are on hummocky, irregular, often concave slopes.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high runoff; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: This soil has been used for livestock grazing, recreation, wildlife habitat, and watershed. In a few areas it has been planted to commercial timber. Naturalized annual and perennial grasses and forbs include tall oatgrass, annual vernal grass, bentgrass, California oatgrass, blue wildrye, bristly dogstail grass, soft brome, wild oat, slender oat, western brackenfern, hairy catsear, common sheep sorrel, miniature lupine, pale flax, common yarrow, and California poppy. In the southern part of the range, scattered coyote brush can be present.Invasion by Douglas fir and succession to forest is in progress in many areas.

DISTRIBUTION AND EXTENT: Coastal Redwood Belt; MLRA 4B. The series is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Redwood National Park portion, Humboldt and Del Norte Area Soil Survey, California, 2001. The source of the name is from Dolason Prairie, located in Redwood National Park south of the town of Orick.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

1. Umbric epipedon - the zone from 0 to 89 centimeters (A1, A2, A3, & A4 horizons)

2. Cambic horizon - the zone from 89 to 150 centimeters (Bw1 & Bw2 horizons)

3. Particle-size control section - the zone from 25 to 100 centimeters, averages 23 percent clay, by field estimate, and 19 percent rock fragments, by volume. CEC/clay ratio averages 0.90

ADDITIONAL DATA: Soil sample 89-RNP-1 was collected from a similar pedon and analyzed chemically at the Oregon state University Soil Testing Laboratory (Lab numbers 71712-71714, 82918 and 82919). Gordon (1980) presented results of chemical analyses on samples (sample P 32) of Dolason soils.

National Soil Survey Laboratory Pedon Nos. 07N0348, 07NO366, 08N0445.

NASIS User Pedon ID: 02CA605REDW059

The Typical Pedon was moved in March of 2004 to better reflect soil properties and characteristics of the Dolason series.

This soil has a dry phase when used in MLRA 5, where it lacks cool, foggy summers.

Soil classified using the 12th Edition of the Keys to Soil Taxonomy. Previously classified as Fine-loamy, mixed, superactive, mesic Humic Dystroxerepts

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National Cooperative Soil Survey
U.S.A.