LOCATION MILPITAS CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Mollic Palexeralfs
TYPICAL PEDON: Milpitas very fine sandy loam - annual grasses and forbs. (Colors are for dry soil unless otherwise noted.)
A11--0 to 8 inches; brown (10YR 5/3) very fine sandy loam, dark brown (10YR 3/3) moist; 0-2" weak medium granular, 2-8" weak medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine roots; many very fine interstitial, common very fine and medium tubular pores; medium acid (pH 5.9); clear smooth boundary. (0 to 8 inches thick)
A12--8 to 20 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine interstitial, and many very fine and medium tubular and common fine tubular pores, medium acid (pH 5.9) gradual smooth boundary. (11 to 24 inches thick)
A13--20 to 24 inches; light brownish gray (10YR 6/2) loam, dark brown (10YR 3/3) moist with 1/4 of area small diffuse blotches of light gray (10YR 7/2); weak coarse subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine interstitial and many very fine and medium tubular pores; medium acid (pH 5.9); clear wavy boundary. (0 to 6 inches thick)
A2--24 to 25 inches; light gray (10YR 7/.2) loam, brown (10YR 5/3) moist; weak medium platy structure; hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine interstitial, common very fine and few fine tubular pores; medium acid (pH 5.8); common 1/8 to 1/4 inch lumps of dark brown clay; abrupt wavy boundary. (1/2 to 5 inches thick)
B21t--25 to 33 inches; dark yellowish brown (10YR 3/4) clay; dark yellowish brown (10YR 3/4) moist; moderate coarse prismatic parting to weak coarse angular blocky structure; extremely hard, firm, very sticky, very plastic; common very fine exped roots, few imped; common very fine and few medium tubular pores; common moderately thick clay films on peds and in medium tubular pores; slightly acid (pH 6.2); tops of prisms flat with A2 horizon penetrating 1/4 to 1/2 inch; gradual smooth boundary. (6 to 12 inches thick)
B22t--33 to 42 inches; yellowish brown (10YR 5/4) fine sandy clay, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic parting to moderate coarse angular blocky structure; extremely hard, firm, very sticky, very plastic; few very fine exped roots; common very fine tubular pores; continuous moderately thick clay films as bridges and in tubular pores and common on peds; mildly alkaline (pH 7.6); gradual smooth boundary. (6 to 12 inches thick)
B3t--42 to 54 inches; brown (7.5YR 5/4) heavy fine sandy clay loam, dark brown (7.5YR 4/4) moist; moderate coarse angular blocky structure; very hard, firm, sticky, plastic; common very fine exped roots; common very fine tubular pores; continuous thin clay films as bridges and common moderately thick films on peds; mildly alkaline (pH 7.8); gradual smooth boundary.
IIC--54 to 68 inches; yellowish brown (10YR 5/4) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; massive, hard, firm, sticky, slightly plastic; common very fine interstitial and few fine tubular pores; continuous thin clay films in bridges with common thick very dark brown (10YR 2/2) films in horizontal streaks, 60 percent gravel; neutral (pH 7.2).
TYPE LOCATION: Santa Barbara County, California; near Elwood, west of Goleta, California; between Highway 101 and railroad right-of-way, 250 feet southeast of intersection of Winchester Canyon Road and Highway 101.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 59 to 62 degrees F. The soil between depths of 6 and 18 inches is usually moist in some part from November sometime in May and is dry all the rest of the year. The soil is medium or slightly acid in the A horizon and slightly acid to mildly alkaline in the B2t horizon, and no free lime is present. The solum is about 40 to 70 inches thick.
The A horizon is fine sandy loam, very fine sandy loam or loam and is brown or grayish brown in 10YR hue. Moist colors in the upper 4 to 6 inches are dark brown to very dark grayish brown in 10YR or 7.5YR hue and the organic matter is 1.3 to 2.0 percent. The A1 horizon becomes massive and hard within 10 inches or less of the surface. The A2 horizon is 1 to 2 units higher in value than the A1 horizon.
The B2t horizon is yellowish brown or dark yellowish brown clay or sandy clay in 10YR hue or brown or dark brown in 7.5YR hue. The interior of some peds has blotches with 5YR hue. The upper boundary of the B2t horizon is abrupt with 20 to 35 percent more total clay in the upper part of the B2t horizon than the overlying A horizon. The upper part of the B2t horizon has moderate to strong prismatic structure and the lower part has moderate to strong angular blocky structure. The C horizon is loam or sandy loam and is gravelly or cobbly in some pedons.
COMPETING SERIES: These are the Hopeton, Kimball, Newville, Positas, San Ysidro, and Tierra series. Hopeton, Kimball, and Newville soils lack A2 horizons. Positas soils have hue of 5YR in the upper part of the B2t horizon. San Ysidro soils have A1 horizons with dry value of 6 and moist value of 3.5 or higher. Tierra soils have chroma of 3 or less in the upper part of the B2t horizon.
GEOGRAPHIC SETTING: Milpitas soils are nearly level to steep on old terraces at elevations of 30 to 500 feet. They formed in alluvium derived largely from sandstone. The climate is subhumid mesothermal with warm dry summers and cool moist winters. Mean annual precipitation is 13 to 19 inches. The average January temperature is about 52 degrees F., average July temperature about 67 degrees F., and mean annual temperature is about 60 degrees F. The average freeze-free season is about 330 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Positas soils and the Sorrento and Watsonville soils. Sorrento soils lack argillic horizons and are calcareous in the lower part of the profile. Watsonville soils have argillic horizons with over 15 percent exchangeable sodium.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; very slow permeability.
USE AND VEGETATION: Pasture, irrigated citrus, and urban. Native vegetation is annual grasses, forbs, widely spaced oak, and coastal sage.
DISTRIBUTION AND EXTENT: Valleys of the coast range and along the coast in south-central California. Milpitas soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Barbara County, California, 1943.
REMARKS: Milpitas soils were formerly classified as Planosols.
OSED scanned by SSQA. Last revised by state on 9/74.