LOCATION HOOKTON CA
Established Series
REV: FWH/FFH/RCH/JPS/ET
04/2016
HOOKTON SERIES
The Hookton series consists of very deep, somewhat poorly drained soils that formed in alluvium derived from mixed sources. Hookton soils are on erosional remnants, drainageways, and dissected terraces. Slopes are 0 to 30 percent. The mean annual precipitation is about 1220 millimeters (48 inches) and mean annual temperature is about 11 degrees C (52 degrees F).
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, acid, mesic Typic Humaquepts
TYPICAL PEDON: Hookton clay loam on a slightly convex south facing slope of 2 percent under seeded pasture at 12 meters (40 feet elevation). (Colors are for moist soil unless otherwise stated. When described May 9, 2007, the soil was moist throughout).
Ap--0 to 27 centimeters (0 to 11 inches); black (10YR 2/1) clay loam, very dark grayish brown (10YR 3/2) dry; moderate medium granular and very fine subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; many very fine and common fine roots throughout; many very fine and fine irregular pores and common very fine and fine tubular pores; 5 percent gravel; very strongly acid (pH 5.0); clear smooth boundary. (25 to 50 centimeters thick)
AB--27 to 42 centimeters (11 to 17 inches); very dark grayish brown (10YR 3/2) clay loam, pale brown (10YR 6/3) dry; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots throughout; common very fine and fine tubular and very fine and fine irregular pores; common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix and on surfaces along root channels; 7 percent gravel; very strongly acid (pH 4.6); clear smooth boundary. (0 to 20 centimeters thick)
Bw1--42 to 70 centimeters (17 to 28 inches); olive brown (2.5Y 4/3) silty clay loam, light yellowish brown (2.5Y 6/3) dry; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few fine roots throughout; common very fine and fine tubular and very fine and fine irregular pores; common fine prominent strong brown (7.5YR 5/8) masses of iron accumulation in the matrix; 10 percent gravel; very strongly acid (pH 4.6); clear smooth boundary.
Bw2--70 to 110 centimeters (28 to 43 inches); dark grayish brown (2.5Y 4/2) clay loam, light brownish gray (2.5Y 6/2) dry; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few fine roots throughout; common very fine and fine tubular and very fine and fine irregular pores; common fine prominent strong brown (7.5YR 5/8) masses of iron accumulation in the matrix; 10 percent gravel; very strongly acid (pH 4.6); clear smooth boundary.
Bw3--110 to 130 centimeters (43 to 51 inches); grayish brown (10YR 5/2) clay loam, pale brown (10YR 6/3) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine, fine and medium irregular pores; many fine prominent strong brown (7.5YR 5/8) masses of iron accumulation in the matrix; 5 percent gravel; very strongly acid (pH 4.5); clear smooth boundary. (combined thickness of the Bw horizons is 30 to 90 centimeters)
BC--130 to 152 centimeters (51 to 60 inches); brown (10YR 5/3) silty clay loam, pale brown (10YR 6/3) dry; massive; moderately hard, very firm, moderately sticky and very plastic; common very fine irregular pores; many fine prominent strong brown (7.5YR 5/8) masses of iron accumulation and common fine faint light brownish gray (10YR 6/2) iron depletions in the matrix; 3 percent gravel; very strongly acid (pH 4.5). (0 to 25 centimeters thick)
TYPE LOCATION: Del Norte County, California; located approximately 30 meters north of Highway 101; HBLM, USGS Smith River Quadrangle; UTM Zone 10 401899mE 4643893mN; NAD83.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 12 to 15 degrees C (54 to 59 degrees F). The difference between the mean winter and mean summer soil temperatures varies from 6 to 9 degrees C. The soils are usually moist and are dry for less than 45 consecutive days in all parts between depths of 10 to 30 centimeters (4 and 12 inches) in the four months following the summer solstice.
Umbric epipedon is 25 to 76 centimeters (10 to 30 inches) thick.
Depth to Redoximorphic features: 25 to 50 centimeters (10 to 20 inches)
The particle-size control section (weighted average)
Rock fragments: 0 to 30 percent
Clay content: 27 to 35 percent
A horizon
Hue: 10YR or 2.5Y.
Value: 3 through 5 dry, 2 or 3 moist.
Chroma: 2 or 3 dry and 1 or 2 moist.
Texture of fine earth: loam, silt loam, or clay loam.
Rock fragments: 0 to 10 percent
Clay content: 22 to 32 percent.
Reaction: very strongly to moderately acid
Bw horizon
Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 2 through 6 dry and moist.
Texture of fine earth: loam, sandy loam, silt loam, silty clay loam or clay loam.
Rock fragments: 0 to 30 percent
Pararock fragments: 0 to 15 percent
Clay content: 27 to 40 percent.
Reaction: very strongly to moderately acid
Redoximorphic features: fine or medium masses of iron accumulation
Quantity: few, common, or many
Hue: 7.5YR, 10YR, or 2.5Y
Value: 3 through 6
Chroma: 4 through 8
Redoximorphic features: fine or medium iron depletions
Quantity: few, common or many
Value: 3 through 6
Chroma: 1 or 2
Some pedons have Bg or C horizons.
Bg or C horizon
Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 1 through 4 dry and moist.
Texture of fine earth: sandy clay loam, silty clay loam, clay loam or silty clay.
Rock fragments: 0 to 10 percent
Pararock fragments: 0 to 40 percent
Clay content: 27 to 45 percent.
Reaction: very strongly to slightly acid
Redoximorphic features: fine or medium masses of iron accumulation
Quantity: few, common, or many
Hue: 7.5YR, 10YR, or 2.5Y
Value: 3 through 6
Chroma: 4 through 8
Redoximorphic features: fine or medium iron depletions
Quantity: few, common or many
Value: 3 through 6
Chroma: 1 or 2
COMPETING SERIES: There are no other soils in this family.
GEOGRAPHIC SETTING: Hookton soils are on erosional remnants, drainageways, and dissected terraces. Slopes are 0 to 30 percent. The soils formed in alluvium derived from mixed sources. Elevations are 3 to 430 meters (10 to 1400 feet). The climate is humid, characterized by warm wet winters and warm moist summers with fog. A strong marine influence limits the diurnal and annual range of temperature. The mean annual temperature is 10 to 14 degrees C (50 to 57 degrees F). The mean annual precipitation is 890 to 2285 millimeters (35 to 90 inches). The frost-free period is 275 to 325 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Arcata, Tablebluff,
Tillas, and
Weott soils. Arcata soils have less than 18 percent clay in the particle size control section. Tablebluff soils have an argillic horizon. Tillas soils do not have redoximorphic features in the upper 100 centimeters. Weott soils have redoximorphic feature within 10 centimeters of the soil surface. Arcata soils are on nearby dissected marine terrace sediments. Tablebluff soils are on nearly level to gently sloping dissected marine terraces. Tillas soils are on alluvial fans. Weott soils are on floodplains.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained; high runoff; moderately low saturated hydraulic conductivity.
USE AND VEGETATION: The soils are used mainly for pasture. Native vegetation is redwood, grand fir, Sitka spruce, California laurel, red alder, willow, bigleaf maple, and salmonberry.
DISTRIBUTION AND EXTENT: Coastal Redwood Belts; MLRA 4B. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Humboldt and Del Norte Counties, California.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Umbric epipedon - the zone from 0 to 27 centimeters. (Ap horizon)
2. Cambic horizon - the zone from 27 to 130 centimeters. (AB, Bw1, Bw2, Bw3)
3. Particle-size control section - the zone from 25 to 100 centimeters, averages 32 percent clay and 8 percent rock fragments.
ADDITIONAL DATA:
Nasis User Pedon ID: 07CA605228.
Type location was moved (8/2007) to current location to update the Typical Pedon and Range of Characteristics and to better represent the series concept. The classification was changed at that time to reflect changes in Taxonomy since the series was proposed. The Hookton soils were formally classified as fine-loamy, mixed, superactive, mesic Humic Dystrudepts
Soil classified using the 12th Edition of the Keys to Soil Taxonomy. 10th Edition classification was fine-loamy, mixed, superactive, mesic, Oxyaquic Dystrudepts.
National Cooperative Soil Survey
U.S.A.