LOCATION SWAINSLOUGH CA

Established Series
Rev: DWH/JTB/SAA/ET
03/2017

SWAINSLOUGH SERIES

The Swainslough series consists of very deep, very poorly drained soils in depressions, backswamps, low flood-plain steps, and reclaimed salt marshes on alluvial plains. These soils formed in alluvium derived from mixed sources. Slopes range from 0 to 2 percent. Mean annual precipitation is about 1015 millimeters (40 inches). Mean annual temperature is about 11 degrees C (51 degrees F).

TAXONOMIC CLASS: Fine, mixed, superactive, nonacid, isomesic Fluvaquentic Endoaquepts

TYPICAL PEDON: Swainslough peat on a less than 1 percent slope under silverweed cinquefoil, spike bentgrass and pasture grasses at an elevation of 2 meters (7 feet). (Colors are for moist soil unless otherwise noted. When described on August 11, 1988 the soil was moist throughout, with a water table at 157 centimeters.)

Oi--0 to 8 centimeters (0 to 3 inches); very dark grayish brown (10YR 3/2) peat, dark grayish brown (2.5Y 4/2) dry, dark yellowish brown (10YR 3/4) rubbed; 80 percent fibers, 40 percent, rubbed; neutral (pH 6.8); abrupt wavy boundary. (0 to 8 centimeters thick)

A--8 to 30 centimeters (3 to 12 inches); dark grayish brown (2.5Y 4/2) silty clay loam, light brownish gray (2.5Y 6/2) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine to coarse roots; many very fine tubular pores; common fine prominent dark yellowish brown (10YR 4/4) iron-manganese masses in the matrix; neutral (pH 7.0); gradual wavy boundary. (10 to 30 centimeters thick)

Bg1--30 to 51 centimeters (12 to 20 inches); dark grayish brown (2.5Y 4/2) silty clay loam, light brownish gray (2.5Y 6/2) dry; moderate very fine and fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many very fine to medium roots; common very fine tubular pores; common fine prominent dark yellowish brown (10YR 4/4) iron-manganese masses in the matrix; neutral (pH 7.0); gradual wavy boundary. (20 to 50 centimeters thick)

Bg2--51 to 74 centimeters (20 to 29 inches); dark grayish brown (2.5Y 4/2) silty clay loam, light brownish gray (2.5Y 6/2) dry; weak very fine and fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine to medium roots; common very fine tubular pores; many fine distinct gray (5Y 5/1) iron depletions and prominent dark yellowish brown (10YR 4/4) iron-manganese masses in the matrix; very few prominent strong brown (7.5YR 4/6) iron stains lining root channels and/or pores; neutral (pH 7.0); abrupt wavy boundary. (0 to 76 centimeters thick)

Bg3--74 to 97 centimeters (29 to 38 inches); dark grayish brown (2.5Y 4/2) silty clay loam, light brownish gray (2.5Y 6/2) dry; massive; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine tubular pores; many fine distinct gray (5Y 5/1) iron depletions and prominent dark yellowish brown (10YR 4/4) iron-manganese masses in the matrix; very few prominent strong brown (7.5YR 4/6) iron stains lining root channels and/or pores; slightly acid (pH 6.5); abrupt wavy boundary. (0 to 92 centimeters thick)

Bg4--97 to 165 centimeters (38 to 65 inches); dark gray (N 4/) silty clay loam, gray (10YR 5/1) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine tubular pores; very few medium prominent strong brown (7.5YR 4/6) iron stains lining root channels and/or pores; moderately acid (pH 6.0). (0 to 76 centimeters thick)

TYPE LOCATION: Humboldt County, California; about 4.8 kilometers northwest of Ferndale; north 1.1 kilometers on Russ Lane, west 0.2 kilometers, and north .0.5 kilometers on right fork, then 400 meters east; 75 meters east and 530 meters north of the southwest corner, Section 33, T.3N., R.2W. HB&M; Ferndale Quadrangle (7.5 minute series); WGS84 Decimal degrees 40.5966667 latitude and -124.3125000 longitude; UTM Zone 10, 388940mE 4494827mN, NAD83.

RANGE IN CHARACTERISTICS:

Soil Moisture: The soil is usually moist in all parts of the soil moisture control section between the depths of 5 to 40 centimeters (2 to 16 inches) in most years, and is saturated in some parts during the months of January through March. The soils have an aquic soil moisture regime.

Soil Temperature: The mean annual soil temperature at 50 centimeters (20 inches)is 12 to 14 degrees C (54 to 59 degrees F). The average summer soil temperature is about 16 degrees C and the average winter soil temperature is about 10 degrees C. The difference between average summer and winter soil temperatures is 6 or less degrees C.

Particle size control section (weighted average):
Clay content: 35 to 45, by weight.

Depth to redoximorphic features: 0 to 10 centimeters (0 to 4 inches)

Endosaturation: The water table is at a depth of 0 to 10 centimeters (0 to 4 inches) from about January through March, between 15 to 60 centimeters (6 to 24 inches) in April, 30 to 90 centimeters (12 to 35 inches) from May through June, 90 to greater than 183 centimeters (35 to greater than 72 inches) from July through November, and rises to between 10 and 60 centimeters (4 to 24 inches)in December.

Some pedons have an O horizon

O horizon
Hue: 10YR
Value: 3, 4 dry
Reaction: neutral

A horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 3 to 5 moist, and 5 to 7 dry
Chroma: 1 or 2 moist, and 2 dry
Texture of fine earth: silty clay loam
Clay content: 27 to 37 percent, by weight
Reaction: moderately acid to neutral

Redoximorphic features: fine and medium iron-manganese masses
Quantity: few or common
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 4 to 8

Bg horizon
Hue: 10YR, 2.5Y, 5Y, or N
Value: 4 or 5 moist, 5 to 7 dry
Chroma: / to 2, moist or dry
Texture of fine earth: silty clay loam or silty clay
Clay content: 30 to 45 percent, by weight
Reaction: moderately acid to slightly alkaline

Redoximorphic features: fine and medium iron-manganese masses in the matrix and iron stains lining root channels and/or pores
Quantity: few, common, or many
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 4 to 8

Redoximorphic features: medium iron depletions
Quantity: common or many
Hue: 5Y, 2.5Y
Value: 4 or 5
Chroma: / to 2

COMPETING SERIES: This is the Occidental soil. The Occidental soil has an electrical conductivity of moderate to strong (8 to 25dS/m).

GEOGRAPHIC SETTING: Swainslough soils are on backswamps, depressions, low-flood-plain steps, reclaimed salt marshes, and tidal marshes on alluvial plains near the Pacific Ocean. Slopes are 0 to 2 percent. These soils formed in alluvium derived from mixed sources. Elevation is 0 to 50 meters (0 to 160 feet). The climate is humid with cool, foggy summers and cool, rainy winters. Mean annual precipitation is 890 to 2030 millimeters (35 to 80 inches). Mean annual air temperature is 10 to 13 degrees C (50 to 55 degrees F). The mean January temperature is about 9 degrees C. The mean July temperature is about 14 degrees C. The frost free season is about 275 to 330 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arlynda, Occidental, Weott, and Worswick soils. The Occidental soils have a water table at or near the surface for longer periods and occur on reclaimed tidal marshes. Arlynda soils have less than 35 percent clay in the particle size control section and occur on backswamps, depressions, meander scars and low-flood-plain steps. Weott soils are in a fine-silty family and occur on higher positions than Swainslough. The Worswick soils are in a coarse-loamy family and occur on backswamps adjacent to natural levees.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Very poorly drained; very high runoff; slow permeability; moderately low saturated hydraulic conductivity. The soils are occasionally flooded for brief periods December through February. The soils are frequently ponded 1 to 15 centimeters for long periods December through March. Some areas are partially drained by ditches and protected by tide gates.

USE AND VEGETATION: These soils are used for pasture, hay, and wetland wildlife habitat. Nearly all areas of this soil have been cleared. The natural vegetation is estimated to be silverweed cinquefoil, rushes, and other hydrophytic vegetation.

DISTRIBUTION AND EXTENT: 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. Name is from a slough west of Ferndale.

REMARKS: Swainslough soils were proposed in May of 2001 as fine, mixed, nonacid, mesic Fluvaquentic Endoaquepts. Reclassification to fine, mixed, superactive, nonacid, isomesic Fluvaquentic Endoaquepts is based on changes in Keys to Soil Taxonomy, Ninth edition, and temperature data recorded in the survey area 2001 through 2004.

Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon - the zone from 0 to 30 centimeters (Oi, A horizon).
2. Cambic horizon - the zone from 30 to 165 centimeters. (Bg1, Bg2, Bg3, and Bg4 horizons)
3. Particle-size control section - the zone from 25 to 100 centimeters averages 36 percent clay, and 12 percent fine sand and coarser (A, Bg1, Bg2, Bg3, and Bg4 horizons)

ADDITIONAL DATA: University of California sample 64-CA-12-008 was collected from the 1964 type location (Soils of Western Humboldt County 1965), sampled as Bayside.

NASIS User Pedon ID: 88CA600048

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

National Cooperative Soil Survey
U.S.A.