LOCATION MILDRED CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Ultic Haploxeralfs
TYPICAL PEDON: Mildred cobbly loam - on a northeast facing slope of 18 percent under whiteleaf manzanita, scattered ponderosa pine and digger pine at an elevation of 1670 feet. (Colors are for dry soil unless otherwise stated.) When described on August 28, l985, the soil was dry throughout.
A--0 to 3 inches; pale brown (10YR 6/3) cobbly loam, dark yellowish brown (10YR 4/4) moist; moderate medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and few fine roots; common very fine interstitial and few very fine tubular pores; 20 percent cobbles, 10 percent pebbles 3 percent stones; slightly acid (pH 6.2); clear wavy boundary. (2 to 15 inches thick)
Bt--3 to 9 inches; light brown (7.5YR 6/4) cobbly clay loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine and few fine roots; common very fine tubular pores; few thin clay films on ped faces and common moderately thick clay films lining pores; slightly acid; 20 percent cobbles, 10 percent pebbles; 3 percent stones; slightly acid (pH 6.4) abrupt smooth boundary. (4 to 12 inches thick)
2Bt1--9 to 15 inches; reddish brown (5YR 4/4) clay, yellowish red (5YR 4/6) moist; strong medium prismatic structure parting to weak medium subangular blocky; hard, firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; common pressure faces; neutral (pH 6.8); clear smooth boundary. (6 to 12 inches thick)
2Bt2--15 to 20 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist; strong medium prismatic structure parting to weak medium subangular blocky; very hard, very firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; common pressure faces; neutral (pH 7.0); clear smooth boundary. (0 to 5 inches thick)
2BCt--20 to 23 inches; reddish yellow (7.5YR 6/6) clay loam; strong brown (7.5YR 5/6) moist; strong medium prismatic structure parting to weak medium subangular blocky; very hard, very firm, very sticky and very plastic; few very fine and medium roots; common very fine tubular pores; few pressure faces; common moderately thick clay films on ped faces and many moderately thick clay films lining pores; neutral (pH 7.0); abrupt wavy boundary. (3 to 8 inches thick)
2Cr--23 inches; mixed reddish yellow (7.5YR 7/8), light gray (10YR 7/1) and white (10YR 8/1) weathered norite.
TYPE LOCATION: Yuba County, California; about 0.75 miles north of Oregon House, California, on Frenchtown Road, then northwest about l mile in Thousand Trails Campground; about 2550 feet south and 1850 feet west of the northeast corner section 35 T.18 N., R.6 E. MDBM, Rackerby Quadrangle.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact ranges from 20 to 40 inches. The mean annual soil temperature is 52 to 56 degrees F. Soil temperature is below 47 degrees from January 1 to February 31. The soil moisture control section is dry in all parts from June 15 to October 31 and is moist in some or all parts from November 1 to June 15.
The A horizon has dry color of 10YR 6/3; 7.5YR 5/6, 5/4, or 5/3 and moist color of 10YR 4/4, 3/4; or 7.5YR 3/4. Clay content ranges from 18 to 27 percent. Rock fragments range from 15 to 35 percent. Stones range from 0 to 5 percent, cobbles from 5 to 25 percent and gravel from 10 to 25 percent. Reaction is moderately acid to slightly acid.
The Bt horizon has dry color of 10YR 6/4; 7.5YR 7/4, 6/4, 5/4 or 5/3 and moist color of 10YR 4/3; 7.5YR 4/6, 4/4, 4/3 or 3/4. Clay content ranges from 27 to 35 percent. Rock fragments range from 15 to 35 percent. Stones range from 0 to 5 percent, cobbles range from 5 to 25 percent, and gravel ranges from 10 to 25 percent. Reaction is slightly acid to neutral. Base saturation is 50 to 75 percent in some part.
The 2Bt horizon has dry color of 10YR 5/3; 7.5YR 6/6, 6/4, 5/5, 5/4; 5YR 5/6, 5/4 or 4/4 and moist color of 10YR 4/3; 7.5YR 5/6, 4/4, 3/4; 5YR 4/6 or 4/4. It has an abrupt upper boundary and is clay loam or clay with 35 to 60 percent clay. It has an absolute clay increase of 15 to 30 percent over the Bt horizon. Rock fragments range from 0 to 15 percent. Cobbles range from 0 to 15 percent and gravel ranges from 0 to 15 percent. Reaction is slightly acid to neutral. Base saturation is 75 to 95 percent.
COMPETING SERIES: These are the Bateman (T), Cornutt, Freezener, Jumpoff, Oak Grove, Rainier and Veneta series. Bateman, Cornutt, Freezener, Jumpoff, Oak Grove, Rainier and Veneta soils have bedrock at more than 40 inches.
GEOGRAPHIC SETTING: Mildred soils are on mountains. Slopes range from 3 to 50 percent. The soils formed in material weathered from basic intrusive igneous rocks trending towards ultra basic, mainly olivine, gabbro and norite. Elevations are 1500 to 2500 feet. The climate is warm, dry summers and cool, wet winters. The average annual precipitation is 35 to 50 inches. The average January temperature is 43 degrees F., the average July temperature is 74 degrees F., and the mean annual temperature is 55 to 59 degrees F. The frost-free season is 190 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Surnuf (T), Orose (T), Verjeles (T) and Flanly (T) series. Surnuf soils are greater than 60 inches deep. Orose soils are less than 20 inches deep to a paralithic contact. Flanly and Verjeles soils are fine-loamy. All are in similar landscape positions.
DRAINAGE AND PERMEABILITY: Well drained, medium to high runoff, very slow permeability.
USE AND VEGETATION: Used mainly for wildlife habitat, recreation and watershed. Natural vegetation is scattered ponderosa pine, California black oak and digger pine with a dense understory of sticky whiteleaf manzanita, McNab cypress, interior live oak, California scrub oak and a few forbs and grasses.
DISTRIBUTION AND EXTENT: Northern part of the Sierra Nevada range in California. The series is not extensive. MLRA is 22.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Yuba County, California, l992.
REMARKS: Mildred soils were originally mapped as the "Rackerby" series in the "Soils of the Yuba Area". University of California, Davis, and Yuba County, l969.
10/2006, runoff terminology changed- DWB. The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
ADDITIONAL DATA: Sampled as reference sample No. S85CA-115-10 for base saturation, mineralogy and particle size. Also sampled by University of California, Davis, in l966.