LOCATION SESPE CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Argixerolls
TYPICAL PEDON: Sespe clay loam, oak-grass vegetation. (Colors are for dry soil unless otherwise noted.)
A1--0 to 12 inches; brown (7.5YR 5/2) clay loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; many very fine and fine and common medium and coarse roots; common very fine tubular pores; medium (pH 6.0); clear wavy boundary. (10 to 14 inches thick)
A3--12 to 18 inches; brown (7.5YR 5/2) heavy clay loam, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky structure; very hard, very firm, sticky and plastic; many very fine and fine, few medium and coarse roots; common very fine tubular pores; medium acid (pH 6.0); gradual irregular boundary. (4 to 6 inches thick)
B21t--18 to 26 inches; reddish brown (5YR 4/3) light sandy clay, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure; very hard, very firm, sticky and plastic; common very fine and fine, few medium and coarse roots; common very fine and fine tubular pores; common moderately thick clay films on faces of peds and lining some pores; slightly acid (pN 6.2); gradual wavy boundary. (0 to 10 inches thick)
B22t--26 to 40 inches; reddish brown (5YR 4/3) sandy clay, dark reddish brown (5YR 3/3) moist; strong medium subangular blocky structure; very hard, very firm, sticky and plastic; common very fine and fine, few medium and coarse roots; common very fine and fine, few medium tubular pores; common moderately thick clay films on faces of peds and many moderately thick clay films lining pores; slightly acid (pH 6.5); clear wavy boundary. (10 to 20 inches thick)
Cr--40 to 48 inches; brownish yellow sandstone, slightly acid (pH 6.5).
TYPE LOCATION: Ventura County, California; approximately 3,900 feet east and 2,640 feet south of the building at the observation point on Casitas Dam.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 24 to 40 inches. The mean annual soil temperature is about 63 degrees F. and the soil temperature usually is not below 47 degrees F. at any time. The soil between depths of about 4 and 12 inches is usually dry all of the time from late May until mid-December and is moist in some or all parts all the rest of the year. Rock fragments of cobblestone size are less than 2 percent and gravel-size fragments are less than 5 percent in all horizons except in the transition to the paralithic contact. Reddish hue is derived mostly from the parent material. Base saturation is more than 75 percent in all parts of the soil profile.
The A horizon is brown, reddish gray, dark reddish gray, or reddish brown (7.5YR 5/2, 4/2; 5YR 5/2, 4/2, 5/3, 4/3). It is heavy loam or clay loam. This horizon has granular or subangular blocky structure and has 3 to 4 percent organic matter in the upper part and 1 to 2 percent organic matter in the lower part. It is neutral to medium acid.
The B2t horizon is dark reddish brown, reddish brown, or weak red (5YR 3/3, 4/3; 2.5YR 5/2, 4/2). It is heavy clay loam, light clay or sandy clay and has 35 to 45 percent total clay. The upper boundary of this horizon is gradual or there is an A3 horizon. The B2t horizon has 5 to 15 percent more clay absolute than the A horizon. It is slightly acid or neutral. Some pedons have a B3 horizon or a C horizon up to 10 inches thick above the paralithic contact. Lime-coatings occur on the upper joints of the sandstone and shale in some pedons.
COMPETING SERIES: These are the Fagan, Gabino, Los Osos, Sween and Todos series. Fagan and Todos soils are 40 to 60 inches deep to bedrock. Gabino soils have 10 to 30 percent rock fragments in the solum and have 10YR hue in the A horizon. Los Osos and Sween soils have hue of 10YR or 2.5Y in the B2t horizon.
GEOGRAPHIC SETTING: The Sespe soils are in the foothills. Slopes range from 15 to 75 percent. Elevations are 400 to 2,600 feet. The soils formed in material weathered from reddish sandstone and shale. The climate is subhumid mesothermal with warm dry summers and cool moist winters. Mean annual precipitation is 16 to 22 inches. Average January temperature is 50 degrees to 53 degrees F., average July temperature is 67 degrees to 73 degrees F., and mean annual temperature is 60 degrees to 61 degrees F. The frost-free season is 250 to 320 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gaviota, Kimball, Lodo, and Sorrento soils. Gaviota and Lodo soils have a lithic contact at depths of less than 20 inches and lack a B2t horizon. Kimball soils lack a paralithic contact within a depth of 40 inches and have less than 1 percent organic matter in the lower part of the A horizon. Sorrento soils lack a paralithic contact and lack a 82t horizon.
DRAINAGE AND PERMEABILITY: Well-drained; rapid and very rapid runoff; slow permeability.
USE AND VEGETATION: Used for woodland, urban use, some grazing, and for growing citrus fruits. Native vegetation is mainly scrub oak, chaparral, and some live-oak trees. Cleared areas not cultivated have annual grasses and forbs.
DISTRIBUTION AND EXTENT: Near the coast in Santa Barbara and Ventura Counties, California. The soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Barbara County (Santa Barbara Area), California, 1945.
OSED scanned by SSQA. Last revised by state on 6/76.