LOCATION ORSET                   CA

Established Series
Rev. JJN/TDC/CEJ/ET
12/2022

ORSET SERIES

The Orset series consists of very deep, well drained soils that formed in alluvium from mixed extrusive igneous rock and volcanic ash. Orset soils are on terraces of basins and streams and have slopes of 0 to 9 percent. The mean annual precipitation is about 35 inches and the mean annual temperature is about 45 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, frigid Typic Xerorthents

TYPICAL PEDON: Orset sandy loam - on a slope of 1 percent under ponderosa pine, white fir, and juniper with an understory of rabbit brush, bitterbrush, Idaho fescue, and prostrate ceanothus, at 5,000 feet elevation. (Colors are for dry soil unless otherwise stated. When described October 7, 1966, the soil was dry from 0 to 26 inches and moist below.)

Oi--0.5 inch to 0; fresh and partially decomposed needles, bark, grass blades, and other organic debris.

A--0 to 4 inches; grayish brown (10YR 5/2) sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, slightly sticky and nonplastic; many medium and common fine roots; many fine interstitial pores; slightly acid (pH 6.5); abrupt smooth boundary. (2 to 6 inches thick)

AC--4 to 13 inches; pale brown (10YR 6/3) sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many medium and common fine roots; many fine interstitial pores; moderately acid (pH 5.8); abrupt smooth boundary. (7 to 11 inches thick)

C1--13 to 26 inches; very pale brown (10YR 7/3) loam, dark brown (10YR 3/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; few medium tubular and many fine interstitial pores; moderately acid (pH 5.8); abrupt smooth boundary. (10 to 15 inches thick)

C2--26 to 42 inches; very pale brown (10YR 7/3) loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few fine and common medium roots; few fine tubular and many fine interstitial pores; moderately acid (pH 5.8); clear smooth boundary. (15 to 30 inches thick)

Cq1--42 to 48 inches; very pale brown (10YR 7/4) loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few fine and medium roots; few fine tubular pores; discontinuous weakly cemented with silica; moderately acid (pH 6.0); abrupt wavy boundary. (4 to 8 inches thick)

Cq2--48 to 60 inches; very pale brown (10YR 7/4) loam, dark brown (10YR 3/3) moist; massive; hard, firm, slightly sticky and slightly plastic; few fine and medium roots; few fine tubular and many fine interstitial pores; discontinuous moderately cemented with silica; moderately acid (pH 6.0).

TYPE LOCATION: Siskiyou County, California; about 3 miles northwest of Horsethief Butte or 10 miles SW of Macdoel, just south of a dirt road on a terrace on the NW side of Horsethief Creek; approximately 800 feet east and 325 feet south of the NW corner of section 33, T.45 N., R.2 W.

RANGE IN CHARACTERISTICS: Depth is 60 inches or more. The mean annual soil temperature is 41 to 48 degrees F; mean July soil temperature is 49 to 62 degrees F. The Soil temperature exceeds 41 degrees F from April 25 to November 20 and exceeds 47 degrees F from May 20 to November 1. Between the depths of 8 and 24 inches, the soil is dry from mid-July until mid-October and is moist in some or all parts the rest of the year. The amount of rock fragments range from 0 to 15 percent. Most are gravel size and less than 3/4 inch in diameter. The upper 7 inches of the soil has dry value of 5.5 or more, and the organic carbon content ranges from 0.3 to 0.6 percent. The soil is moderately acid or slightly acid. Base saturation ranges from 50 to 80 percent and is greater than 60 percent in some part of the upper 30 inches of the soil. The soil is sandy loam or loam with 10 to 18 percent clay.

The A horizon is grayish brown, brown, light brownish gray, or pale brown (10YR 5/2, 5/3, 6/2, 6/3). Moist colors are very dark brown, very dark grayish brown, or dark brown (10YR 2/2, 3/2, 3/3).

The AC horizon is light brownish gray, pale brown, light gray or very pale brown (10YR 6/2, 6/3, 7/2, 7/3). Moist colors are very dark grayish brown, dark brown, or dark grayish brown (10YR 3/2, 3/3, 4/2, 4/3).

The C and Cq horizons are light brownish gray, pale brown, light gray, very pale brown, or white (10YR 6/2, 6/3, 7/2, 7/3, 7/4, 8/2, 8/3; 2.5Y 6/2, 7/2, 8/2). Moist colors are very dark grayish brown, dark brown, or dark grayish brown (10YR 3/2, 3/3, 4/2, 4/3; 2.5Y 3/2, 4/2). Most pedons have slight brittleness but are moderately or strongly brittle in some part of the C horizon. Cementation with silica is at depths of 40 to 60 inches and commonly becomes stronger with increasing depth. Both the brittleness and cementation is discontinuous.

COMPETING SERIES: These are the Catherine, Esro, Lance and Stoner series in other families. Catherine and Esro soils have a thick mollic epipedon and fine-silty control section. Lance soils are mesic and have a fine-silty control section. Stoner soils have a cambic horizon and have mesic soil temperatures.

GEOGRAPHIC SETTING: Orset soils are on terraces of basins and streams. Slopes are 0 to 9 percent. The soils formed in alluvium from mixed extrusive igneous rock and volcanic ash. The soils appear to have formed under poorer drainage conditions than currently exist.

Elevations are 4,500 to 6,000 feet. The climate is continental and subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 20 to 50 inches. Seasonal snowfall is 12 to 24 inches. Mean January temperature is 25 to 30 degrees F; mean July temperature is 62 to 65 degrees F; and mean annual temperature is 42 to 46 degrees F. Frost-free season is 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Avis, Iller, Pinehurst, Sheld and the competing Esro soils. Avis soils have an ashy-skeletal control section. Iller soils have a medial-skeletal over loamy-skeletal control section. Sheld soils have a medial control section. Pinehurst soils have a thick mollic epipedon and fine-loamy argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderately slow permeability.

USE AND VEGETATION: Used for summer grazing, woodland, wildlife habitat and recreation. Native vegetation is bitterbrush, Idaho fescue, bluebunch wheatgrass, rabbitbrush, prostrate ceanothus, ponderosa pine and Douglas fir, white fir, and juniper.

DISTRIBUTION AND EXTENT: Cascade Mountain range in northern California, MLRA 22B. Series is not extensive.

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

SERIES ESTABLISHED: Siskiyou County, California, 1978.

REMARKS: Soil was sampled (9/18/85) and sent to Lincoln Laboratory.

Sample Depth Organic Base Saturation
No. (CM) Carbon Sum NH4OAC

851298 10-33 0.46 66 83
851299 33-66 0.37 63 71
851300 66-76 72 85

The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET

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National Cooperative Soil Survey
U.S.A.