LOCATION OSSAGON                 CA

Established Series
Rev: JPS/ET
10/2016

OSSAGON SERIES

The Ossagon series consists of very deep, well drained soils formed in colluvium and residuum from weakly consolidated fluvial, beach, and dune deposits derived from mixed sources. Ossagon soils are on mountains and hills and have slopes of 9 to 50 percent. The mean annual precipitation is about 1900 millimeters (75 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isomesic Typic Haplohumults

TYPICAL PEDON: Ossagon loam - on a northwest-facing slightly convex slope of 24 percent under redwood, Sitka spruce, red alder, cascara, western hemlock, California blackberry, salmonberry, salal, California huckleberry, swordfern, and deer fern at 55 meters (180 feet) elevation. (Colors are for moist soil unless otherwise stated. When described June 29, 1988, the soil was moist throughout.)

Oi--0 to 10 centimeters (0 to 4 inches); fresh and slightly decomposed conifer needles, alder leaves and twigs, and mosses and fungus; very strongly acid (pH 4.5); clear smooth boundary. (2 to 10 centimeters thick)

A--10 to 31 centimeters (4 to 12 inches); very dark brown (10YR 2/2) loam, dark grayish brown (10YR 4/2) dry; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and common medium roots; common very fine and common fine interstitial and common very fine and fine and few medium tubular medium pores; moderately acid (pH 6.0); clear wavy boundary. (10 to 40 centimeters thick)

AB--31 to 41 centimeters (12 to 16 inches); brown (10YR 4/3) clay loam, yellowish brown (10YR 5/4) dry; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine, fine, medium and coarse roots; common very fine and fine tubular, few medium tubular pores; moderately acid (pH 6.0); clear wavy boundary. (0 to 25 centimeters thick)

BAt--41 to 73 centimeters (16 to 29 inches); strong brown (7.5YR 4/6) loam, brownish yellow (10YR 6/6) dry, weak coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; common very fine and fine, few medium tubular pores; common faint clay films on faces of peds; moderately acid (pH 6.0); gradual wavy boundary. (0 to 35 centimeters thick)

Bt--73 to 121 centimeters (29 to 48 inches); brown (7.5YR 4/4) clay loam, brownish yellow (10YR 6/6) dry, weak coarse and very coarse subangular blocky structure; moderately hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; common very fine and fine and few medium tubular pores; common distinct clay films on surfaces along root channels, few faint clay films on faces of peds; very strongly acid (pH 5.0); gradual wavy boundary. 25 to 126 centimeters thick)

BCt--121 to 131 centimeters (48 to 52 inches); yellowish brown (10YR 5/8) sandy loam, brownish yellow (10YR 6/6) dry, massive; soft, very friable, slightly sticky and slightly plastic; few very fine and fine, medium and coarse and roots; few very fine and fine tubular pores; many faint clay films between sand grains; very strongly acid (pH 4.5); abrupt wavy boundary.

BCt2--131 to 141 centimeters (52 to 56 inches); yellowish brown (10YR 5/8) very gravel loamy sand, brownish yellow (10YR 6/6) dry; massive; soft, very friable, slightly sticky and slightly plastic; few fine and fine roots; few very fine tubular pores; 43 percent rounded gravel; few distinct clay films on rock fragments; very strongly acid (pH 5.0); clear wavy boundary. (Combined thickness of BCt horizons is 0 to 60 centimeters thick)

C--141 to 200 centimeters (52 to 79 inches); light brownish gray (2.5Y 6/2) sandy loam, pale yellow (2.5Y 7/4) dry; massive; slightly hard, very friable, nonsticky and slightly plastic; common fine and few fine and medium roots; common very fine and fine tubular pores; very strongly acid (pH 4.5). (0 to 100 centimeters thick)

TYPE LOCATION: Redwood National Park, Humboldt County, California; Roadcut on abandoned logging road, due southeast from junction of May Creek road and Highway 101, WGS84 Decimal degrees 41.3476111 latitude and -124.0192778 longitude; HBLM; USGS Orick Quadrangle. UTM Zone 10 414728mE 4577846mN, NAD83

RANGE IN CHARACTERISTICS:

Soil Moisture: The soil is moist in all parts in the soil moisture control section throughout the year. The soils have an Udic moisture regime.

Soil Temperature: The mean annual soil temperature is 10 to 13 degrees C (50 to 55 degrees F). The difference between mean summer and mean winter temperature is 2 to 4 degrees C.

Organic Matter: There is 12 to 25 kg per square meter of organic carbon to a depth of one meter.

Reaction is moderately to very strongly acid throughout. Base saturation is 5 to 35 percent between depths of 25 to 200 centimeters.

Particle-Size Control Section (weighted average):

Rock fragments: 0 to 13 percent gravel.
Clay content: 26 to 32 percent clay.

O horizon

Hue: 10YR.
Value: 2 through 6 dry and moist.
Chroma: 1 through 4 dry and moist.

Texture: slightly decomposed organic material.
Wood fragments: 0 to 35 percent.
Reaction: moderately to very strongly acid.

A horizon

Hue: 7.5YR or 10YR.
Value: 3 through 5 dry, 2 or 3 moist.
Chroma: 2 or 3 dry, 2 or 3 moist.

Texture of fine earth: loam.
Rock fragments: 0 to 13 percent gravel.
Clay content: 18 to 25 percent.

Bt horizon

Hue: 7.5YR, 10YR, or 2.5Y.
Value: 4 through 7 dry, 3 through 6 moist.
Chroma: 4 through 8 dry, 4 through 8 moist.

Texture of fine earth: loam, silt loam, clay loam or silty clay loam.
Rock fragments: 0 to 13 percent gravel.
Clay content: 18 to 32 percent.

C horizon

Hue: 7.5YR, 10RY, or 2.5Y
Value: 5 through 7 dry, 4 through 6 moist.
Chroma: 2 through 8 dry, 2 through 8 moist.

Texture of fine earth: loamy sand, sandy loam, or fine sandy loam
Rock fragments: 0 to 45 percent gravel.
Clay content: 0 to 10 percent.

COMPETING SERIES: These are the Espa, Ladybird and Stonehill series. Espa lacks rock fragments within the profile. Ladybird soils have angular rock fragments throughout. Stonehill soils are 50 to 100 centimeters deep to a lithic contact.

GEOGRAPHIC SETTING: Ossagon soils occur on mountain slopes, sideslopes of hill and on broad ridges. Slopes are 9 to 50 percent. Elevations are 6 to 593 meters (15 to 1945 feet). The soils formed in colluvium and residuum from weakly consolidated fluvial, beach, and dune deposits derived from mixed sources. The climate is humid with cool foggy summers and cool moist winters. Coastal influence limits the annual and diurnal range in temperature. Mean annual precipitation ranges from 1520 to 2290 millimeters (60 to 90 inches). Mean January temperature is about 9 degrees C; mean July temperature is about 13 degrees C; and the mean annual temperature is 10 to 13 degrees C (50 to 55 degrees F). Frost-free season is 240 to 325 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mettah, Squashan, and the Surpur soils. Mettah soils are fine-silty and are redder than 7.5YR throughout. Squashan soils have greater than 35 percent rock fragments in the particle-size control section. Surpur soils have an ochric epipedon. Mettah and Surpur soils are found on broad ridge tops at higher elevations, farther inland.

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

USE AND VEGETATION: This soil has been used for commercial timber and is used for wildlife recreation, and watershed. Natural vegetation consists of redwood, Sitka spruce, red alder, Douglas fir, western hemlock, tanoak, cascara, western thimbleberry, salmonberry, salal, and swordfern.

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

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

SERIES ESTABLISHED: Humboldt Del Norte area, California 2007. Source of name is from Ossagon Creek north of the town of Orick.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon - the zone from 0 to 31 centimeters.
2. Argillic horizon - the zone from 31 to 141 centimeters.
3. Ultisol feature - base saturation of 20 percent at the critical depth, 125 centimeters below the upper boundary of the argillic horizon
4. Haplohumult features - Clay does not remain at least 80 percent of its maximum to a depth of 200 centimeters
5. Particle-size control section - the zone from 31 to 81 centimeters, averages 26 percent clay and 20 percent fine sand or coarser.

ADDITIONAL DATA: Supporting data from a similar Ossagon pedon; NSSL, Lincoln Lab sample number 03N0670.

NASIS User Pedon ID: 88CA605REDW021

Soils classified using Keys to Soil Taxonomy, 12th edition.

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National Cooperative Soil Survey
U.S.A.