LOCATION SMITHNECK               CA

Established Series
Rev. HRS/SJB/DJE/TKK
03/2023

SMITHNECK SERIES

The Smithneck series consists of very deep, somewhat poorly drained soils formed in alluvium from mixed rock sources. Smithneck soils are on flood plains or alluvial fans. Slopes are 1 to 10 percent. Mean annual precipitation is about 475 mm and the mean annual air temperature is about 9 degrees C.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Oxyaquic Argixerolls

TYPICAL PEDON: Smithneck sandy loam on a nearly level slope in a field of wheatgrass and alfalfa at about 1,520 meters elevation. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 15 cm; dark gray (10YR 4/1) sandy loam, black (10YR 2/1) moist, 8 percent clay; weak thick platy and moderate very fine granular structure; slightly hard, friable, nonsticky, slightly plastic; many very fine, fine, and medium roots; many very fine, fine and medium tubular pores; slightly acid (pH 6.4); gradual smooth boundary. (13 to 23 cm thick)

A2--15 to 38 cm; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist, 10 percent clay; weak thick platy and moderate fine granular structure; hard, friable, slightly sticky, slightly plastic; many very fine and fine roots; many very fine and fine tubular pores; slightly acid (pH 6.4); clear wavy boundary. (15 to 25 cm thick)

BAt--38 to 58 cm; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist, 13 percent clay; weak, medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; many very fine and fine, and few medium roots; many very fine and fine tubular and interstitial pores; common clay films lining pores and as bridges; neutral (pH 6.7); gradual wavy boundary. (0 to 23 cm thick)

Bt--58 to 81 cm; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist, 17 percent clay; few fine distinct light yellowish brown (10YR 6/4) mottles, dark yellowish brown (10YR 4/4) moist; massive; very hard, friable, sticky, slightly plastic; common very fine and fine roots; many very fine and common medium tubular and interstitial pores; many thin clay films lining pores and as bridges; neutral (pH 7.0); clear wavy boundary. (18 to 30 cm thick)

BCt--81 to 122 cm; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist, 18 percent clay; few light yellowish brown (10YR 6/4) and common fine distinct dark yellowish brown (10YR 4/4) mottles moist; massive; hard, friable, slightly sticky, slightly plastic; many very fine and few medium roots; many very fine and fine, and common medium tubular and interstitial pores; common thin clay films lining pores and as bridges; neutral (pH 7.0); clear wavy boundary.

2C--122 to 152 cm; this horizon consists mainly of stratified fine gravel, gravelly loamy coarse sand and sandy loam which are light brownish gray (10YR 6/2) with white mineral grains, dark grayish brown (10YR 4/2) with common fine faint dark yellowish brown (10YR 4/4) mottles, moist and 10 percent clay.

TYPE LOCATION: Sierra County, California; approximately 1/2 mile southeast of Loyalton, near the Smithneck Canyon Road, 1,420 feet north and 20 feet east of the south 1/4 corner sec. 18, T.21N., R.16E. WGS84 39.668776 latitude and -120.230981 longitude; UTM zone 10, 4394661 meters N, 737518 meters E WGS84.

RANGE IN CHARACTERISTICS:
Soil temperature: The mean annual soil temperature at 50 cm is 10 to 11 degrees C and the difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a mesic temperature regime.

Soil Moisture: The soils have a xeric soil moisture regime. The soil moisture control section (about 20 to 60 cm) is usually dry in all parts from July 15 to November 15 and is moist in some or all parts all the rest of the year.

Diagnostic Feature(s):
Mollic epipedon thickness: 28 to 48 cm
Argillic horizon thickness: 40 to 110 cm

Water Features: Seasonal high water table: 70 cm
Flooding: rare, very brief from January through March

Depth to redoximorphic features: 50 to 70 cm

Particle size control section weighted average:
Rock fragments: 0 to 10 percent gravel
Clay content: 4 to 18 percent

A horizon(s)
Hue: 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 to 3 dry or moist
Texture: coarse sandy loam, sandy loam, fine sandy loam, loam
Clay content: 4 to 18 percent
Rock fragments: 0 to 10 percent gravel
Reaction: slightly acid

Bt horizon(s) or BCt horizon (where present)
Hue: 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 2 or 3, dry or moist
Texture: sandy loam or fine sandy loam
Clay content: 10 to 18 percent
Rock fragments: 0 to 10 percent gravel
Reaction: neutral

Absolute clay increase from the A to the Bt horizon is 3 to 6 percent.

C horizon(s)
Hue: 10YR or 2.5Y dry, 10YR moist
Value: 5 or 7 dry, 4 moist
Chroma: 2 or 4 dry, 2 to 4 moist
Texture: stratified gravelly loamy coarse sand, sandy loam, fine sandy loam, loam
Clay content: 4 to 15 percent
Rock fragments: 0 to 34 percent gravels
Reaction: Slightly acid to neutral

COMPETING SERIES: This is the Beckwourth series. Beckwourth soils have secondary carbonates in the subsoil.

GEOGRAPHIC SETTING: Smithneck soils are on flood plains, stream terraces or footslopes of alluvial fans. Elevation is 1,570 to 1,795 meters. Slopes are 1 to 10 percent. These soils formed in alluvium from mixed rock sources. The climate is Mediterranean with warm, dry summers and cold, moist winters. Mean annual precipitation is 315 to 685 mm. The mean annual air temperature is about 9 degrees C. The frost free season is 90 to 145 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Balman, Bidwell, Coolbrith, James Canyon and Ramelli soils. The Calman soils are fine-loamy and have calcareous A horizons. Bidwell soils have calcareous Bt horizons and are fine-loamy. Coolbrith soils have Bt horizons with 27 to 35 percent clay. James Canyon soils are fine-loamy and are poorly drained. The Ramelli soils are clayey over loamy and are poorly drained.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderately high to high saturated hydraulic conductivity, slow runoff; A seasonal high water table is at a depth of 70 to 150 cm at some time from December to June. Flooding is rare for very brief periods from January through March. Drained phases are recognized that have a seasonal high water table at 1.7 to 2 meters due to stream channel entrenchment.

USE AND VEGETATION: Used mainly for growing alfalfa and small grains, wheatgrass pastures and native meadow. The vegetation is mainly perennial and annual meadow grasses, forbs and silver sagebrush. Drained phases have big sagebrush.

DISTRIBUTION AND EXTENT: Northeastern Sierra County and Western Plumas County, California. These soils are of small extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Sierra County, California 1973.

REMARKS:
Particle Size Control Section for this pedon: 38 to 88 cm.
Diagnostic horizons and features recognized in this pedon are:
Mollic Epipedon 0 to 81 cm
Argillic Horizon 38 to 122 cm
Aquic Conditions 58 to 152 cm
Redox Concentrations 58 to 152 cm
Endosaturation 58 to 152 cm
Lithologic Discontinuity 122 to 152 cm

ADDITIONAL DATA:
Pedon information for this type location only:
Pedon Type: OSD pedon
Pedon Purpose: soil survey inventory
NASIS User Pedon ID: 1967CA091006

Taxonomy was updated from a Coarse-loamy, mixed, superactive, mesic Pachic Argixeroll, to a Coarse-loamy, mixed, superactive, mesic Oxyaquic Argixeroll on 03/2023.

This soil was classified using the 13th edition of the Keys to Soil Taxonomy.

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National Cooperative Soil Survey
U.S.A.