LOCATION WITHERELL CA
The Witherell series consists of very deep, somewhat excessively drained soils formed in material weathered from sandstone. Witherell soils are loamy in the upper part of the profile with fragmental gravel in the lower. These soils are on hills and mountains and have slopes of 5 to 75 percent. The mean annual precipitation is about 1500 millimeters (50 inches) and the mean annual temperature is about 14 degrees C (57 degrees F.).
TAXONOMIC CLASS: Fragmental, mixed, thermic Typic Haploxerepts
TYPICAL PEDON: Witherell loam - on a south facing convex slope of 30 percent under annual grasses at 550 feet elevation. (Colors are for dry soil unless otherwise noted. When described June 14, 1978, the soil was dry throughout.)
A--0 to 3 centimeters (0 to 1 inch); brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure parting to moderate fine granular; slightly hard, friable, nonsticky and nonplastic; many very fine and common fine roots throughout; common very fine and fine interstitial pores; 5 percent gravel (2 to 5 millimeters); strongly acid (pH 5.2); clear wavy boundary. (3 to 8 centimeters thick)
Bw--3 to 18 centimeters (1 to 7 inches); light yellowish brown (10YR 6/4) loam, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few very fine and common fine roots; few very fine and fine interstitial pores; 5 percent gravel (2 to 5 millimeters); very strongly acid (pH 4.9); clear wavy boundary. (10 to 20 centimeters thick)
Bt--18 to 30 centimeters (7 to 12 inches); light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and common fine roots; few very fine and fine interstitial pores; few faint clay films bridging mineral grains; 5 percent gravel (2 to 10 millimeters); many faint silt coatings lining pores; very strongly acid (pH 4.8); clear wavy boundary. (10 to 20 centimeters thick)
C--30 to 200 centimeters (12 to 79 inches); gray (10YR 5/1) gravel, strongly cemented fractured sandstone; fractures are 0.5 centimeters to 10 centimeters apart and are less than 1 millimeters wide; many faint silt coatings lining fracture faces; few very fine roots in fractures; 95 percent angular gravel, rock is mostly fractured in place.
TYPE LOCATION: Mendocino County, California; about 1 mile south of Boonville; about 1/2 mile west on Hutsell Road from the intersection of Hutsell Road and Highway 128, about 1,000 feet southwest from feeder barn; 500 feet north and 200 feet west of the southeast corner of section 11, T.13 N., R.14 W.; Ornbaun Valley Northeast Quadrangle; 38.994385 latitude and -123.3651116lonitude, 468381.8mE, 4316216.9mN, zone 10 NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil from a depth of 18 centimeters (7 inches) to lithic material is moist in all parts from November 1 to May 1 and is dry in all parts from June 1 to October 15 in most years.
Soil temperature: 15 to 19 degrees C.
Depth to fragmental material with fractures less than 10 centimeters apart is 25 to 36 centimeters.
Hue: 10YR or 7.5YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 through 6 dry, 3 or 4 moist
Reaction: strongly acid through neutral.
Clay content: 12 to 27 percent
Texture of the fine earth: sandy loam or loam
Coarse fragment content: 0 to 15 percent gravel
Hue: 10YR or 7.5YR
Value: 5 through 7 dry, 3 or 4 moist
Chroma: 3 through 6, dry or moist
Clay content: 12 to 30 percent
Texture of the fine earth: sandy loam, clay loam, or loam
Rock fragment content: 0 to 25 percent gravel
Reaction: very strongly through slightly acid
Clay content: 12 to 27 percent in the fine earth fraction. Texture of the fine earth: sandy loam or loam
Rock fragment content: 91 to 95 percent gravel
COMPETING SERIES: There are no other series in the family.
GEOGRAPHIC SETTING: Witherell soils occur on hills and mountains. Slopes are 5 to 75 percent. Elevations are 90 to 1220 meters (300 to 4,000 feet). The soils formed in material weathered from sandstone. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation varies from 900 to 1780 millimeters (35 to 70 inches). Occasional snow occurs above 3,000 feet. Mean January temperature is 7 degrees C. (44 degrees F); mean July temperature is 22 degrees C. (72 degrees F); and mean annual temperature is 14 degrees C. (57 degrees F). The frost-free period is 125 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Hopland, and Frogwoman soils. All of these soils are over 50 centimeters deep to a paralithic or lithic contact.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat excessively drained; surface runoff under bare soil conditions is moderate to high; moderately high to high saturated hydraulic conductivity.
USE AND VEGETATION: This soil is used for livestock grazing and wildlife habitat. Vegetation is annual grasses and forbs.
DISTRIBUTION AND EXTENT: Northern coastal California. The series is not extensive. MLRA 5 and 15.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mendocino County, California, Eastern Part, 1985.
REMARKS: This soil was reclassified in January 2008 due to the presence of bedrock with cracks mostly closer together than 10 centimeters and coatings on the rock fragments. The soil lacks a lithic contact but has material weathered from residuum. The original concept had fractured bedrock within 25 to 50 centimeters. In order to not have a contrasting particle size control section, depth to the fragmental material is restricted to 25 to 36 centimeters.
Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon: the zone from 0 to 3 centimeters. (A horizon)
2. Cambic horizon: the zone from 3 to 30 centimeters (Bw, Bt horizons) There is a slight increase in clay content over the A horizon, but it is not enough to meet the requirements of an argillic horizon.
3. Particle-size control section - the zone from 25 to 100 centimeters centimeters has 1 percent clay by weight, and 89 percent gravel by volume. (Bt and C horizons)
4. Fragmental material - the zone from 30 to 200 centimeters (C horizon)
Where Witherell is used in MLRA 15, it needs to be re-examined.
Keys to Soil Taxonomy, 12th edition.
National Cooperative Soil Survey