LOCATION BLUCHER CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Fluvaquentic Haploxerolls
TYPICAL PEDON: Blucher silt loam, on a smooth east facing slope of 2 percent under soft chess, burclover, birdsfoot trefoil, and annual rye at 5 feet elevation. (Colors are for dry soil unless otherwise stated. When described (6/12/78) the soil was moist below 7 inches.)
Ap--0 to 7 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; many fine faint strong brown (7.5YR 5/6) mottles, strong brown (7.5YR 4/6) moist; moderate medium and coarse prismatic, moderate coarse and very coarse subangular blocky structure; hard, friable, sticky and plastic; many very fine, common fine and medium roots; common very fine tubular and interstitial pores; compaction from animal traffic apparent; moderately acid (pH 6.0); clear smooth boundary. (5 to 9 inches thick)
A12--7 to 16 inches; brown (10YR 5/3) loam, very dark grayish brown (10YR 3/2) moist; few fine faint yellowish brown (10YR 5/4) mottles, dark yellowish brown (10YR 4/4) moist; weak coarse and very coarse prismatic structure parting to moderate coarse and very coarse subangular blocky; very coarse structure less than 1/2 of horizon; hard, friable, sticky and plastic; common very fine and medium roots; many very fine, common fine and medium tubular pores; filled krotovina apparent; slightly acid (pH 6.5); abrupt smooth boundary. (7 to 11 inches thick)
IIC1--16 to 23 inches; brown and pale brown (10YR 5/3, 6/3) silt loam, dark brown and dark grayish brown (10YR 3/3, 4/2) moist; moderate thin through very thick platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, few fine roots; common fine and medium, few coarse tubular pores; many thin strata of very fine sand and silt occur in this horizon; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 10 inches thick)
IIIC2g--23 to 39 inches; gray and grayish brown (10YR 5/1, 5/2) silty clay loam, very dark gray and very dark grayish brown (10YR 3/1, 3/2) moist; many medium distinct yellowish brown (10YR 5/6) mottles, dark yellowish brown (10YR 4/6) moist; moderate medium through very coarse angular blocky structure; very hard, firm, sticky and plastic; common very fine roots; common very fine tubular pores; very fine sand strata; moderately alkaline (pH 8.0); gradual smooth boundary. (12 to 19 inches thick)
IIIC3g--39 to 60 inches; gray (10YR 6/1) clay loam, dark gray (10YR 4/1) moist; many medium distinct brown (7.5YR 5/4) mottles, brown and dark brown (7.5YR 4/4) moist; moderate medium through very coarse angular blocky structure; very hard, firm, sticky and plastic; common very fine roots; common very fine tubular pores; roots tend to follow vertical cracks; charcoal present; water table observed at 47 inches; slightly alkaline (pH 7.8).
TYPE LOCATION: Marin County, California; 3/4 mile east of Hwy 101 on paved road along south side of San Antonio Creek heading toward Neils Island, on Lester Corda property, 75 feet east of animal waste pond, 30 feet south of road to Neils Island, 122 degrees 35 feet 14 inches W. longitude, 38 degrees 11 feet 11 inches N. latitude.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is about 59 degrees to 63 degrees F. The soil moisture control section (4 to 12 inches) is moist in all parts from mid-December to April. It is dry in all parts from mid July to October. There are no carbonates in any part of the profile. The particle-size control section averages 18 to 35 percent clay. The soils are strongly stratified.
The A horizon has dry color of 10YR 3/1, 3/2, 4/1, 4/2, 5/1, 5/2, or 5/3 with mottles of 10YR 5/4, 5/6, 4/4; or 7.5YR 5/6. It has moist color of 10YR 2/1, 2/2, 3/1, 3/2, or 3/3. It is sandy loam, fine sandy loam, loam, silt loam, or clay loam. The upper part of this horizon is moderately acid to slightly acid; the lower part is slightly acid or neutral.
The IIC horizon has dry color of 10YR 5/1, 5/2, 5/3, 6/2, 6/3; 2.5Y 5/2; or 5Y 7/2. Some pedons have l0YR 5/6, 5/8, 6/4, 6/8; 7.5YR 5/6, or 5/8 mottles. This horizon is fine sandy loam, silt loam, or loam. It is slightly alkaline or moderately alkaline.
The IIIC horizon has dry color of 10YR 4/1, 5/1, 5/2, 6/1 or 6/2 with mottles of 10YR 4/4, 4/6, 5/6, 5/8, or 7.5YR 5/4. It has moist color of 10YR 2/1, 3/1, 3/2, 4/1, or 4/2. It is silty clay loam or clay loam. It is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Lakeside and Pacheco series in the same family. Lakeside soils are calcareous through the series control section and have an sa horizon. Pacheco soils are calcareous within depths of 20 inches and are only weakly stratified.
GEOGRAPHIC SETTING: Blucher soils are in basins and on alluvial fans. Slopes are from 2 to 5 percent. The soils formed in alluvium from mixed sources. Elevations are 0 to 500 feet. The climate is subhumid mesothermal with warm dry summers and cool moist winters. The mean annual precipitation is 25 to 50 inches. Mean January temperature is about 55 degrees F.; mean July temperature is about 65 degrees F.; mean annual temperature is about 60 degrees F. Frost-free season is 210 to 290 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Clear Lake, Cole, Cortina, Goldridge, and Steinbeck soils. Clear Lake and Cole soils have a fine particle-size control section. Cortina soils have a loamy-skeletal particle-size control section. Goldridge soils have an argillic horizon and have less than 35 percent base saturation in the lower part of the C horizon. Steinbeck soils have mean annual soil temperature of less than 59 degrees F. and an ustic moisture regime.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderate over slow permeability. A water table occurs at a depth of 3.5 to 5 feet from December to April.
USE AND VEGETATION: Used for rangeland, hay and pasture, and some row crops. Native vegetation is soft chess, burclover, annual fescue, ryegrass, wiregrass and dock.
DISTRIBUTION AND EXTENT: North coastal valleys of California. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Marin County, California, 1979.
REMARKS: The activity class was added to the classification in January of 2003. Competing series were not checked at that time. - ET