LOCATION DUZEN CA

Established Series
REV. JWH/SAA/
07/2016

DUZEN SERIES

The Duzen series consists of very deep, well drained soils formed in alluvium derived from mixed sedimentary sources. Duzen soils are on river terraces and have slopes of 0 to 5 percent. The mean annual precipitation is about 1780 millimeters (70 inches) and the mean annual temperature is about 12 degrees C (54 degrees F).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Fluventic Humixerepts

TYPICAL PEDON: Duzen loam - on a slope of 2 percent under annual grasses at 152 meters elevation. (Colors are for dry soil unless otherwise noted). When described on March 13, 2009, the soil was moist throughout.

A1--0 to 24 centimeters; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; 21 percent clay; moderate fine subangular blocky structure parting to moderate fine granular structure; friable, moderately hard, slightly sticky and slightly plastic; common fine roots and many very fine roots; few very fine tubular pores; 10 percent subrounded very strongly cemented gravel; moderately acid (pH 5.6); clear smooth boundary.

A2--24 to 40 centimeters; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; 21 percent clay; moderate fine subangular blocky structure; friable, moderately hard, slightly sticky and moderately plastic; common very fine roots; few very fine tubular pores; 10 percent subrounded very strongly cemented gravel; moderately acid (pH 5.8); clear smooth boundary.

A3--40 to 75 centimeters; light brownish gray (10YR 6/2) gravelly clay loam, very dark grayish brown (10YR 3/2) moist; 18 percent clay; weak medium subangular blocky structure; friable, moderately hard, moderately sticky and moderately plastic; 30 percent subrounded very strongly cemented gravel; moderately acid (pH 5.8); clear smooth boundary. (Combined thickness of the A horizons is 25 to 75 centimeters)

C--75 to 200 centimeters; light brownish gray (10YR 6/2) extremely gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; 10 percent clay; massive structure; very friable, soft, nonsticky and nonplastic; 60 percent subrounded very strongly cemented gravel, 20 percent subrounded very strongly cemented cobbles, and 1 percent subrounded very strongly cemented stones; moderately acid (pH 6.0). (Thickness of the C horizons is 125 to 175 centimeters)

TYPE LOCATION: Humboldt County, California; 700 meters east of Swains flat at CA 36. 480 meters west and 300 meters south of the NE corner of section 17, T.1N., R.3W.; U.S.G.S. 7.5 minute quadrangle Bridgeville, California: WGS84 Decimal degrees 40.4680550 latitude, -123.8587129 longitude: UTM Zone 10 427203mE, 4480063mN; NAD 83.

RANGE IN CHARACTERISTICS:

Soil moisture: The soil between the depths of 15 and 45 centimeters is moist in all parts from November 1 to May 1. The SMCS is dry in all parts for 70 consecutive days following the summer solstice. The soils have a xeric soil moisture regime.

Soil temperature: The mean annual air temperature is 13 to 15 degrees C. The difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a thermic soil temperature regime.

Umbric epipedon: 25 to 50 centimeters thick

Particle size control section (weighted average):
Rock fragments: 40 to 65 percent mostly as gravel and cobbles.
Clay content: 18 to 27 percent
Reaction: moderately acid to slightly acid

Surface A horizon:
Hue: 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 through 3, dry or moist
Clay content: 18 to 27 percent
Rock fragments: 5 to 15 percent gravel
Reaction: moderately acid
Lithochromic colors

Lower A horizons:
Hue: 10YR
Value: 4 through 6 dry, 2 or 3 moist
Chroma: 1 through 3, dry or moist
Texture of the fine earth: loam, sandy loam, and clay loam
Clay content: 15 to 35 percent
Rock fragments: 5 to 60 percent mostly as gravel and cobbles
Reaction: moderately acid or slightly acid

C horizons:
Hue: 10YR
Value: 4 through 6 dry, 2 or 3 moist
Chroma: 1 through 3, dry or moist
Texture of the fine earth: loam or sandy loam
Clay content: 10 to 20 percent
Rock fragments: 50 to 85 percent mostly as gravel and cobbles
Reaction: moderately acid or slightly acid

COMPETING SERIES: There are no other series in this family.

GEOGRAPHIC SETTING: The Duzen soils occur on river terraces that are no longer subject to flooding. Slopes are 0 to 5 percent. Elevations are 45 to 310 meters. The soils formed in alluvium derived from mixed sedimentary sources. The climate is humid with cool foggy summers and cool moist winters. Mean annual precipitation ranges from 1270 to 2032 millimeters. Mean January temperature is about 6 degrees C; mean July temperature is about 17 degrees C; and the mean annual temperature is about 13 degrees C. The frost-free period is 275 to 350 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Garberville and Parkland soils which exist on similar landform positions. Garberville and Parkland soils contain less than 35 percent coarse fragments in the control section.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained and moderately high saturated hydraulic conductivity. Runoff is low. The soils are frequently ponded for brief periods December through March.

USE AND VEGETATION: All of these soils exist as cleared openings. This soil is used for non-irrigated and irrigated pasture. Vegetation consists of annual and perennial grasses and herbs.

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 County Soil Survey, Central Part, California, 2016; proposed 2014. The name is from the Van Duzen River.

REMARKS: Diagnostic features and horizons recognized in this pedon are:
1. Umbric epipedon -- the zone from 0 to 40 centimeters (A1, A2).
2. Fluvent feature - an irregular decrease in organic-carbon content between the depths of 25 and 125 centimeters .
3. Particle size control section: The zone from 25 to 100 centimeters averages 24 percent clay by weight, 36 percent gravel and 6 percent cobble (A2, A3, and C horizons).

5. Dark colors at depth are considered lithochromic in nature.

ADDITIONAL DATA:

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

NASIS User Pedon ID 09CA600197

National Cooperative Soil Survey
U.S.A.