LOCATION SAMOA CA
Established Series
Rev: JTB/SAA/ET
05/2016
SAMOA SERIES
The Samoa series consists of very deep, somewhat excessively drained soils formed in eolian and marine sand derived from mixed sources. Samoa soils are on recently stabilized dunes on dune fields and coastal plains. Slope ranges from 2 to 50 percent. Mean annual precipitation is about 1000 mm (39 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).
TAXONOMIC CLASS: Mixed, mesic Typic Udipsamments
TYPICAL PEDON: Samoa sand, on a west northeast-facing 50 percent slope under California polypody, coyotebrush, yellow bush lupine, beach tansy, Brewers rush, and ripgut brome at an elevation of 6 meters (20 feet). When described on April 18, 2002, the soil was moist throughout. (Colors are for moist soil unless otherwise noted).
Oi--0 to 1 cm (0 to 0.5 inches); slightly decomposed moss, grass, and forb litter, very dark brown (10YR 2/2) rubbed; 95 percent fibers, 5 percent rubbed; moderately acid (pH 5.6). (0 to 6 centimeters)
A1--1 to 4 cm (0.5 to 2 inches); very dark brown (10YR 2/2) sand, dark brown (10YR 3/3) dry; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots throughout; many very fine irregular pores; moderately acid, (pH 6.0); clear wavy boundary.
A2--4 to 14 cm (2 to 6 inches); very dark grayish brown (2.5Y 3/2) sand, grayish brown (2.5Y 5/2) dry; 30 percent weak fine subangular blocky structure, soft, very friable, nonsticky and nonplastic; 70 percent single grain, loose, loose, nonsticky and nonplastic; many very fine, common fine and medium, and few coarse roots throughout; few very fine tubular pores; 5 percent fine distinct dark yellowish brown (10YR 4/4) iron-manganese masses along root channels; moderately acid, (pH 6.0); gradual wavy boundary. (Combined thickness of the A horizons is 0 to 25 centimeters thick)
AC--14 to 45 cm (6 to 18 inches); very dark grayish brown (2.5Y 3/2) sand, grayish brown (2.5Y 5/2) dry; single grain, loose, nonsticky and nonplastic; common very fine, fine, and medium and few coarse roots throughout; many very fine and fine interstitial pores; 1 percent fine distinct dark yellowish brown (10YR 4/4) iron-manganese masses along root channels; moderately acid, (pH 6.0); gradual wavy boundary. (0 to 100 centimeters thick)
C--45 to 160 cm (18 to 63 inches); dark olive gray (5Y 3/2) sand, olive gray (5Y 5/2) dry; single grain, loose, nonsticky and nonplastic; few very fine, fine, and medium roots throughout; many very fine and fine interstitial pores; slightly acid, (pH 6.4). (50 to 200 centimeters thick)
TYPE LOCATION: Humboldt County, California; about 3 miles west of the town of Arcata; Section 34, T.6N., R.1W., Humboldt Baseline and Meridian; USGS 7.5 minute quadrangle Eureka, CA; WGS84 Decimal degrees 40.8649167 latitude, -124.161583 longitude; UTM Zone 10 402112mE, 4524410mN; NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: The soil moisture control section between 36 to 109 centimeters (14 to 43 inches) is dry in all parts for less than 45 days following the summer solstice. The soils have a udic moisture regime.
Soil Temperature: The mean annual soil temperature at 50 centimeters (20 inches) is 12 to 15 degrees C (54 to 59 degrees F). The mean summer soil temperature is about 18 degrees C and the mean winter soil temperature is about 11 degrees C. The difference between mean summer and winter soil temperature is between 6 and 9 degrees C.
Redoximorphic features may develop from brief and localized saturated conditions around root channels during the winter months, rather than from the presence of free water throughout the soil profile.
Electrical Conductivity: nonsaline (0 to 2 mmhos/cm)
Surface fragments: 0 to 5 percent gravel
Particle size control section (weighted average):
Rock fragments: 0 to 30 percent gravel
Clay content: 0 to 1 percent
O horizon
Hue: 10YR
Value: 3, 4 dry
Reaction: neutral
A Horizon:
Hue: 10YR, 2.5Y, or 5Y
Value: 2 and 3 moist, 3 to 6 dry
Texture: loamy fine sand, fine sand, sand
Chroma: 1 to 3, moist or dry
Clay: 0 to 5 percent, by weight
Rock fragments: 0 to 5 percent gravel
Reaction: moderately acid
Redoximorphic Features: fine iron-manganese masses along root channels
Quantity: none to few
Hue: 10YR or 2.5Y
Value: 4 and 5
The A and O horizons are missing in areas where the dunes have sparse dune mat vegetation or have been recently stabilized by European beach grass.
C Horizon:
Hue: 2.5Y or 5Y
Value: 3 or 4 moist, 5 dry
Chroma: 1 to 3, moist or dry
Texture: fine sand, sand
Clay: 0 to 1 percent, by weight
Reaction: slightly acid to neutral
Rock fragments: 0 to 30 percent gravel
COMPETING SERIES: These are the
Acquango,
Aldo,
Bigapple,
Biltmore,
Boplain,
Breeze,
Caesar,
Chute,
Dabney,
Hodge,
Oakville,
Osolo,
Pahuk,
Penwood,
Perks,
Pinegrove,
Plainfield, Poquonok,
Rikers,
Sardak,
Sarpy,
Scotah,
Spessard,
Suncook,
Tyner,
Windsor and
Wapanucket series. Acquango soils are very slightly to moderately saline within the series control section. Aldo soils have a saturated zone between 1 and 2 meters for as much as 1 month per year in normal years. Bigapple soils have anthrotransported materials over 100 centimeters thick. Biltmore soils have flakes of mica throughout. Boplain soils have a paralithic contact within the series control section. Breeze soils contain more than 10 percent (by volume) construction debris. Caesar, Oakville, Osolo, Penwood,
Poquonock, and Spessard, and Windsor soils have Bw horizons with chromas greater than 3. Chute, Sardak, and Sarpy soils contain free carbonates. Dabney, Perks, and Suncook soils are formed in sandy alluvium. Hodge soils contain more than 40 percent silt plus clay plus very fine sand in the particle-size control section. Pahuk soils have relict redoximorphic features in the lower third of the series control section. Pinegrove soils formed in acid regolith from surface mine operations. Plainfield, Scotah, and Tyner soils have Bw horizons with hues of 10YR and 7.5YR. Rikers soils contain an average of greater than 35 percent rock fragments of carboliths and coal slag. Wapanucket soils have a lithologic discontinuity within the series control section.
GEOGRAPHIC SETTING: Samoa soils are on recently stablized dunes on dune fields and coastal plains. Slopes are 2 to 50 percent. Elevations are 0 to 20 meters (0 to 65 feet). These soils formed in eolian and marine sand derived from mixed sources. The climate is humid with cool, foggy summers and cool, rainy winters. Mean annual precipitation is 890 to 2030 millimeters (35 to 80 inches). The mean annual temperature is 12 to 15 degrees C (54 to 59 degrees F). Frost free season is about 275 to 330 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Lanphere and
Clambeach soils. Lanphere and Clambeach soils have mean summer and mean winter soil temperatures that differ by less than 3 degrees C. Lanphere soils occur on stabilized dunes under forest vegetation. Clambeach soils are very poorly drained and occur in deflation basins and depression.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat excessively drained; low runoff; rapid permeability; very high saturated hydraulic conductivity.
USE AND VEGETATION: This soil is used mainly for plant and wildlife habitat and recreation. Native vegetation includes American beachgrass, yarrow, beach strawberry, beach wormwood, Humboldt wallflower (endangered), beach tidytips, coastal sand verbena, goldenrod, beach suncups, camphor tansy, creamcups, beach-bur, European searocket, seaside buckwheat, silky beach pea, seaside fleabane, seashore false bindweed, pink sand verbena, California polypody, Brewers rush, coyote brush, and scattered shore pine. Many areas of the Samoa soil are dominated by non-native European beachgrass planted to stabilize dunes and prevent sand movement. Other non-native vegetation includes yellow bush lupine, iceplant, pampas grass, and other grasses and forbs.
DISTRIBUTION AND EXTENT: Coastal Redwood Belt; MLRA 4B. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Soil Survey of Redwood National and State Parks, California, 2008. The name is from the Samoa Peninsula.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon: The zone from 0 to 18 centimeters. (Oi, A, and AC horizons)
2. Particle size control section: The zone from 25 to 100 centimeters (AC and C horizons)
ADDITIONAL DATA:
NASIS User Pedon ID: 02CA600020
Soil classified using Keys to Soil Taxonomy, 12th edition.
National Cooperative Soil Survey
U.S.A.