LOCATION ROJO CA

Established Series
RD:TAC/JJJ/WCL/DJE
02/2023

ROJO SERIES

The Rojo series consists of moderately deep, well drained soils that formed in material weathered from lacustrine tuff and volcanic ash. Rojo soils are on undulating terraces and have slopes of 0 to 9 percent. The mean annual precipitation is about 12 inches and the mean annual temperature is about 48 degrees F.

TAXONOMIC CLASS: Ashy, glassy, mesic Vitritorrandic Durixerolls

TYPICAL PEDON: Rojo sandy loam--on a 5 percent slope in a potato field at 4,440 feet elevation., (When described on January 11, 1984, the soil was moist throughout. Colors are for dry soil unless otherwise stated.)

Ap--0 to 8 inches; brown (7.5YR 5/2) sandy loam, dark reddish brown (5YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine interstitial and few very fine tubular pores; 5 percent pebbles; neutral (pH 7.0); clear smooth boundary. (7 to 9 inches thick)

A--8 to 13 inches; brown (7.5YR 5/2) sandy loam, dark reddish brown (5YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine interstitial and few very fine tubular pores; 5 percent pebbles; neutral (pH 7.3); clear wavy boundary. (4 to 6 inches thick)

Bw1--13 to 20 inches; pinkish gray (7.5YR 6/2) sandy loam, reddish brown (5YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine roots; common very fine interstitial, tubular and few fine tubular pores; 5 percent pebbles; slightly alkaline (pH 7.5); gradual wavy boundary. (6 to 12 inches thick)

Bw2--20 to 28 inches; light reddish brown (5YR 6/3) sandy loam, reddish brown (5YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine roots; common very fine interstitial, tubular and few fine tubular pores; 5 percent pebbles; slightly alkaline (pH 7.5); abrupt wavy boundary. (8 to 13 inches thick)

2Bkqm--28 to 30 inches; pink (5YR 7/3) strongly cemented duripan; reddish brown (5YR 5/4) moist; massive; very hard and brittle, very firm; has continious laminar bands 1 to 2 mm thick throughout; roots are horizontal and on top of the pan; few fine closed tubular pores; moderately alkaline (pH 8.0) slightly effervescent with a thin layer of lime .5 to 1 mm on top of this horizon; abrupt wavy boundary. (1 to 4 inches thick)

2Cr--30 inches; pink (5YR 7/3) weathered lacustrine tuff and volcanic ash, reddish brown (5YR 5/4) moist.

TYPE LOCATION: Siskiyou County, California; about 11 miles east of Macdoel, 3,750 feet north of Red Rock road, 115 feet west of fence line; 1,900 feet north, 1,850 feet east of the southwest corner of section 31, T. 46 N., R. 2 E.

RANGE IN CHARACTERISTICS: The thickness of the solum and depth to the duripan ranges from 25 to 40 inches. The mean annual soil temperature ranges from 48 to 52 degrees F. The soil temperature at a depth of 20 inches is above 41 degrees F from about March 15 to December 1 (255 days) and is above 47 degrees F from about April 15 to November 15 (210 days). The soil between depths of 8 to 24 inches is dry in all parts from about June 15 until November 10 (145 days). The soil moisture control section is dry more than half the time the soil temperature is above 41 degrees F. Mollic epipedon ranges from 11 to 15 inches. Clay content ranges from 10 to 18 percent.

The A horizon has dry color of 7.5YR 5/2 or 5YR 5/2 and moist color of 7.5YR 3/2. Gravel range from 0 to 10 percent.

The B horizon has dry color of 7.5YR 6/2, 6/4, 5YR 6/3 or 7/3 and moist color of 7.5YR 5/4, 5YR 4/3, 5/3 or 5/4. Gravel range from 0 to 10 percent. Reaction ranges from neutral to mildly alkaline.

COMPETING SERIES: These are the Baker series in the same family and the Willis and Blalock series. Baker soils have 10YR hues and lack bedrock below the duripan. Blalock soils are less than 20 inches in depth to the duripan. Willis soils have a coarse silty particle-size control section.

GEOGRAPHIC SETTING: Rojo soils are on undulating terraces. Slopes are 0 to 9 percent. The soils formed in material weathered from lacustrine tuff and volcanic ash. Elevations are from 4,035 to 4,600 feet. The climate is semiarid with warm dry summers and cool moist winters. The average annual precipitation is about 10 to 14 inches. Snowfall is 20 to 30 inches. The average annual temperature is about 46 to 50 degrees F. The average January temperature is about 27 degrees F and the average July temperature is about 63 degrees F. Frost-free season is about 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Eastable, Hedox. Porterfield and Stukel soils. Eastable soils are very deep. Porterfield and Stukel soils are shallow to bedrock. Hedox soils do not have a duripan.

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

USE AND VEGETATION: Rojo soils are used for cropland, hay and pasture and rangeland. Vegetation is bluebunch wheatgrass, Idaho fescue, mountain big sagebrush, Nevada bluegrass and rabbitbrush.

DISTRIBUTION AND EXTENT: Northcentral California. These soils are not extensive.

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

SERIES PROPOSED: Siskiyou County, California, Butte Valley-Tule Lake Soil Survey, 1985.

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

Mollic epipedon--Zone from the surface of the soils to a depth of 13 inches (Ap, A2, Bw1).

Cambic horizon--The zone from about 13 to 28 inches (Bw1, Bw2) color and structure.

Duripan--The zone from about 28 to 30 inches.

Paralithic contact--at 30 inches.

Control section--The zone from about 10 inches to the pan. Coarse loamy family--sandy loam with about 10 percent clay, 66 percent sand and 24 percent silt by hydrometer method.

Aridic moisture--Dry 145 days. The zone from a depth of about 8 to 24 inches.

National Cooperative Soil Survey
U.S.A.