LOCATION MUDCO CAEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic, shallow Argiduridic Durixerolls
TYPICAL PEDON: Mudco gravelly sandy loam - on a north facing 2 percent slope in a plowed field at 4,400 feet elevation. (When described on September 5, 1981, the soil was dry throughout.)
A1--0 to 3 inches; grayish brown (10YR 5/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; moderate very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and plastic; many very fine and fine roots; many very fine interstitial, common very fine tubular pores; 15 percent pebbles; neutral (pH 7.0); clear smooth boundary.
A2--3 to 7 inches; grayish brown (10YR 5/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and plastic; common very fine and fine roots; many very fine interstitial, common very fine tubular pores; 15 percent pebbles; neutral (pH 7.0); clear smooth boundary. (The combined thickness of the A horizon is 5 to 9 inches).
Bt1--7 to 10 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and plastic; common very fine and fine roots; common very fine interstitial and tubular pores; few thin clay films on faces of peds; 10 percent pebbles; neutral (pH 7.0); clear wavy boundary.
Bt2--10 to 14 inches; brown (7.5YR 5/2) gravelly sandy clay loam, dark brown (7.5YR 4/2) moist; weak medium subangular blocky structure; hard, firm, sticky and plastic; common very fine and fine roots; common very fine interstitial and tubular pores; common thin clay films on faces of peds and interstitial pores; 15 percent pebbles; neutral (pH 7.0); clear wavy boundary.
Bt3--14 to 17 inches; brown (7.5YR 5/4) gravelly sandy clay loam, dark brown (7.5YR 4/4) moist; weak medium subangular blocky structure; hard, firm, sticky and plastic; few very fine and fine roots; few very fine interstitial and tubular pores; common moderately thick clay films on faces of peds and interstitial pores; 20 percent pebbles; neutral (pH 7.0); abrupt wavy boundary. (The combined thickness of the Bt horizon is 5 to 11 inches).
Bqm--17 to 60 inches; pink (7.5YR 7/4) indurated duripan, brown (7.5YR 5/4) moist, massive; extremely hard, extremely firm and brittle, roots are horizontal and matted on top of this horizon; has opal laminar cap that is 1 to 3 millimeters thick; neutral (pH 7.3).
TYPE LOCATION: Siskiyou County, California; about 300 feet south of Red Rock Valley Road, 1,000 feet north and 2,150 feet west of the southeast corner of sec. 2, T. 45 N., R. 1 E.
RANGE IN CHARACTERISTICS: The depth to the duripan ranges from 10 to 20 inches. The mean annual soil temperature is 48 to 50 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 10 to 20 inches is dry in all parts from 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.
The A horizon has dry color of 10YR 5/2, 5/3; 7.5YR 5/2 or 5/4 and moist color of 10YR 3/2 or 3/3. Clay content ranges from 5 to 10 percent. Content of organic matter ranges from 1 to 2 percent in the surface 5 to 9 inches. Gravel range from 15 to 25 percent.
The Bt horizon has dry color of 10YR 5/3, 5/4; 7.5YR 5/2 or 5/4 and moist color of 10YR 3/4, 4/3; 7.5YR 3/4, 4/2 or 4/4. The Bt horizon is sandy loam or gravelly sandy clay loam with the clay content ranging from 10 to 25 percent and average greater than is percent clay.
The Bqm horizon has dry color of 10YR 6/2, 6/3; 7.5YR 7/2 or 7/4 and moist color of 10YR 4/3, 4/4 or 7.5YR 5/4. The Bqm is indurated and has massive or platy structure. The Bqm is extremely or very hard when dry and extremely or very firm when moist and is always brittle. It contains gravel size fragments (2 to 5 millimeter) of basalt and tuff. Thin seams of silica occur throughout the Bqm.
COMPETING SERIES: These are the Aned, Roval and Terlan (T) series. Aned soils are calcareous in the duripan, lack gravel in the solum and have a mean annual soil temperature that ranges from 53 to 54 degrees F. Roval series are calcareous and moderately or strongly alkaline in the lower part of the solum and have a mean annual soil temperature that ranges from 53 to 54 degrees F. Terlan series are calcareous in the lower part of the B horizon and in the duripan.
GEOGRAPHIC SETTING: Mudco soils are on terraces. Slopes are 2 to 5 percent. The soils formed in alluvium from tuff and basalt. Elevation is 4,300 to 4,600 feet. The climate is semiarid with warm dry summers and cold moist winters. Mean annual precipitation is 10 to 14 inches. Snowfall is 10 to 20 inches. Mean January temperature is about 30 degrees F.; mean July temperature is about 65 degrees F.; mean annual temperature is about 48 degrees F. Frost-free season is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fordney, Modoc, Munnell and Rojo. Fordney soils are greater than 60 inches deep and have a sandy particle control section. Modoc and Rojo soil are 20 to 40 inches deep to a duripan. Munnell soils are greater than 60 inches deep and have contrasting particle size control sections.
DRAINAGE AND PERMEABILITY: Well drained; runoff is slow; moderately slow permeability.
USE AND VEGETATION: Used mainly for cropland. Crops commonly grown are irrigated wheat, barley and oats.
DISTRIBUTION AND EXTENT: North Central California eastern Siskiyou County, in Red Rock Valley. These soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Siskiyou County, California, 1986.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon--zone from the surface to a depth of 7 inches (A1, A2 horizons).
Argillic horizon--zone from 7 to 17 inches (Bt1, Bt2, Bt3 horizons).
Textural Control: Zone from 7 inches to the duripan. The textural control section is 23 percent clay.
Duripan: Zone from 17 to 60 inches.
Moisture regime--Aridic-zone from about 12 inches to the lithic contact. Moisture control section is dry (less than 15 bar) throughout 145 days and dry greater than 1/2 the time soil temperature is above 41 degrees F.
OSED scanned by SSQA. Last revised by state on 4/86.