LOCATION PASTUREROCK CA

Established Series
Rev: JHP/JPS/ET/KP
03/2017

PASTUREROCK SERIES

The Pasturerock series consists of very deep, well drained soils formed in colluvium derived from sandstone and mudstone. Pasturerock soils are on mountains and have slopes of 15 to 50 percent. The mean annual precipitation is about 2290 millimeters (90 inches) and the mean annual temperature is about 13 degrees C (55 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Ultic Haploxeralfs

TYPICAL PEDON: Pasturerock loam - on a convex, west-facing slope of 45 percent under Oregon white oak, annual and perennial grasses, and forbs at 686 meters (2250 feet) elevation. (Colors are for moist soil unless otherwise stated. When described on May 5, 1981 and redescribed on June 22, 1989, the soil was moist throughout.)

Oi-- 0 to 2 centimeter (0 to 1 inch); slightly decomposed oak leaves and herbaceous litter; moderately acid (pH 6.0). (0 to 4 centimeters thick)

A--2 to 12 centimeters (1 to 5 inches); very dark grayish brown (10YR 3/2) loam, grayish brown (10YR 5/2) dry; moderate fine and medium subangular blocky structure; friable, sticky and slightly plastic; many very fine, common fine roots; many fine irregular and common fine and medium tubular pores; about 8 percent small gravel; slightly acid (pH 6.3); abrupt irregular boundary. (6 to 60 centimeters thick)

AB--12 to 20 centimeters (5 to 8 inches); very dark grayish brown (10YR 3/2) clay loam, grayish brown (10YR 5/2) dry; moderate medium and coarse subangular blocky structure; firm, moderately sticky and moderately plastic; common very fine, fine and medium roots; common fine irregular, and common fine and medium tubular pores; about 5 percent small gravel; moderately acid (pH 5.9); clear wavy boundary. (8 to 25 centimeters thick)

Bt1--20 to 42 centimeters (8 to 17 inches); very dark grayish brown (10YR 3/2) clay loam, grayish brown (10YR 5/2) dry; moderate coarse subangular block structure; firm, moderately sticky and moderately plastic; many fine and medium, and common very fine and coarse roots; common fine and medium, and few coarse tubular pores; few faint clay films on surfaces along pores and on all faces of peds; about 8 percent gravel; moderately acid (pH 5.7); gradual wavy boundary.

Bt2--42 to 90 centimeters (17 to 35 inches); dark grayish brown (10YR 4/2) very cobbly clay loam, light brownish gray (10YR 6/2) dry; weak coarse subangular blocky structure; firm, moderately sticky and moderately plastic; common fine, medium and coarse roots; few fine and medium tubular pores; few faint clay films in on all faces of peds and on surfaces along pores; 20 percent gravel, 15 percent cobbles; moderately acid (pH 5.7); clear wavy boundary. (Combined thick of the Bt horizons is 45 to 105 centimeters)

BCt--90 to 122 centimeters (35 to 48 inches); brown (10YR 5/3) gravelly clay loam, pale brown (10YR 6/3) dry; weak coarse subangular blocky structure; firm, moderately sticky and moderately plastic; few fine, medium and coarse roots; few fine tubular pores; few faint clay films in on all faces of peds and on surfaces; 25 percent gravel; moderately acid (pH 5.7); diffuse smooth boundary. (20 to 60 centimeters thick)

C--122 to 174 centimeters (48 to 69 inches); brown (10YR 5/3) extremely gravelly sandy clay loam, pale brown (10YR 6/3) dry; massive; firm, moderately sticky and very plastic; few fine, medium and coarse roots; few fine tubular pores; 75 percent gravel; moderately acid (pH 5.6). (Combined thickness 30 to 65 centimeters thick)

TYPE LOCATION: Redwood National Park, Humboldt County, California; cutbank near headwaters of north fork, Slide Creek, 20 feet south of Counts Hill Prairie; southwest quarter, northeast quarter, section 10, T. 9 N., R. 2 E., 41 degrees, 11 minutes and 09 seconds north 41.1833333 latitude and -123.9286111 123 degrees, 55 minutes, 43 seconds west longitude; HBLM; USGS Ball Hills Quadrangle. Zone UTM 10 422118mE 4559536mN; NAD83.

RANGE IN CHARACTERISTICS:

Soil Moisture: The soil is usually moist in all parts in the soil moisture control section from about November 1 to July 15, and is dry in all parts from about July 15 to October 15 in most years. The soils have a xeric moisture regime.

Soil Temperature: The mean annual soil temperature is 10 to 15 degrees C (50 to 59 degrees F). The difference between mean summer and mean winter temperature is 6 to 10 degrees C.

The umbric epipedon is 25 to 75 centimeters thick.

Base saturation is greater than 35 percent throughout, and may be higher near the surface, reaches a minimum in the Bt, and then increases with depth.

Particle-Size Control Section (weighted average):

Rock fragments: 5 to 35 percent gravel and 0 to 10 percent cobbles.
Clay content: 27 to 35 percent clay.

O horizon

Hue: 10YR.
Value: 2 through 6 dry and moist.
Chroma: 1 through 4 dry and moist.

In lieu of texture: slightly decomposed organic material.
Wood fragments: 0 to 35 percent.
Reaction: neutral to moderately acid.

A horizon

Hue: 10YR or 2.5Y.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3 dry, 2 or 3 moist.

Texture of fine earth: loam.
Rock fragments: 3 to 34 percent gravel and 0 to 5 percent cobbles.
Clay content: 22 to 27 percent clay.
Reaction: slightly to strongly acid.

Bt horizon

Hue: 10YR or 2.5Y.
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 2 through 4 dry, 2 through 4 moist.

Texture of fine earth: silty clay loam or clay loam.
Rock fragments: 5 to 34 percent gravel and 0 to 10 percent cobbles.
Clay content: 27 to 34 percent clay.
Reaction: moderately to strongly acid.

C horizon

Hue: 10YR or 2.5Y.
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 2 through 4 dry, 1 through 4 moist.

Texture of fine earth: sandy clay loam, clay loam, or silty clay loam.
Rock fragments: 15 to 75 percent gravel and 0 to 10 percent cobbles.
Clay content: 27 to 38 percent clay.
Reaction: moderately acid to neutral.

COMPETING SERIES: These are the Bigridge (CA), Hospiter (CA), Hotaw (CA), Millerridge (CA), Minniecreek (CA), Sitton (OR), Speaker (OR), Willakenzie (OR). Bigridge soils are 100 to 150 centimeters deep to a paralithic contact. Hospiter soils have hues of 7.5YR or redder throughout. Hotaw, Minninecreek, Speaker and Willakenzie soils are 50 to 100 centimeters deep to a paralithic contact. Millerridge soils are 50 to 100 centimeters deep to a paralithic contact. Sitton soils have less than 5 percent rock fragments in the particle-size control section/

GEOGRAPHIC SETTING: Pasturerock soils are on mountain slopes. Slopes gradients are 15 to 50 percent. Elevations are 53 to 1220 meters (170 to 4000 feet). The soils formed in colluvium derived from sandstone and mudstone. The climate is humid with cool, foggy summers and cool, rainy winters. This soil also has a dry phase when used in MLRA 5, where there is no marine layer influence in the summers. Mean annual precipitation is 1525 to 2550 millimeters (60 to 100 inches). Mean January temperature is about 7 degrees C; mean July temperature is about 15 degree C; and the mean annual temperature is 10 to 15 degree C (50 to 59 inches). Frost free season is about 200 to 260 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coyoterock, Doolyville and Maneze soils. Coyoterock and Doolyville soils have redoximorphic features in the particle-size control section. Maneze soils lack an argillic horizon and greater than 35 percent rock fragments in the particle-size control section. Coyoterock soils are in moist locations on poorly incised drainages, hillslope hollows, and earthflows. The Doolyville soils are on smooth to rounded earthflow slopes in moist locations below Pasturerock soils. Maneze soils are on convex slopes and spur ridges alongside Pasturerock soils.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very high runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: This soil has been used for livestock grazing, wildlife habitat, and watershed. The native vegetation is oak woodland. Species include Oregon white oak, California black oak, poison oak, annual and perennial grasses and forbs, with scattered big-leaf maple, Douglas fir and California bay. Some areas have abundant pacific swordfern. Invasion by Douglas-fir and succession to forest is in progress in many areas.

DISTRIBUTION AND EXTENT: California Coastal Redwood Belt; MLRA 4B. The series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Humboldt and Del Norte area, California, 2007. The source of the name is from "Pasture Rock", a prominent rock outcrop, located in Redwood National Park south of the town of Orick.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

1. Umbric epipedon - the zone from 2 to 42 centimeters - base saturation, by ammonium acetate, is less than 50 percent in the zones from 20 to 42 centimeters (A, AB & Bt1 horizons)
2. Argillic horizon - the zone from 20 to 122 centimeters (Bt1, Bt2 & BCt horizons)
3. Ultic Haploxeralfs feature - base saturation, by ammonium acetate, is less than 50 percent in the zones from 20 to 42 centimeters and 122 to 174 centimeters Bt1 & C horizons)
4. Particle-size control section - the zone from 20 to 70 centimeters, averages 34 percent clay, by field estimate, and 18 percent rock fragments, by volume. CEC/clay ratio averages 0.40.

ADDITIONAL DATA: Soil sample 81-RNP-74 through 81-RNP-79 Pedon #15 was collected from a similar pedon and analyzed chemically at the Oregon State University Soil Testing Laboratory.

NASIS User Pedon ID 81CA605REDW014.

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

National Cooperative Soil Survey
U.S.A.