LOCATION AZULE CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Mollic Haploxeralfs
TYPICAL PEDON: Azule clay loam, rangeland. (Colors are for dry soil unless otherwise noted).
A--0 to 6 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (2.5Y 3/2) moist; massive; hard, firm, sticky and plastic; many fine and very fine roots; many very fine, common fine and few medium tubular pores; slightly acid (pH 6.5); clear smooth boundary. (6 to 18 inches thick).
Bt1--6 to 12 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (2.5Y 3/2) moist; moderate coarse prismatic parting to strong medium angular blocky structure very hard, very firm, slightly sticky and slightly plastic; many fine and common very fine roots; many very fine and fine tubular pores; common thin clay films on faces of peds and lining pores; slightly acid (pH 6.5); diffuse smooth boundary. (4 to 8 inches thick).
Bt2--12 to 21 inches; dark grayish brown (2.5Y 4/2) clay, very dark grayish brown (2.5Y 3/2) moist; moderate coarse prismatic parting to moderate medium angular blocky structure; very hard, very firm, sticky and very plastic; many fine and very fine roots; many very fine and fine, few medium pores; common moderately thick clay films on faces of peds and lining pores; slightly acid (pH 6.5); gradual irregular boundary. (7 to 12 inches thick).
Bt3-21 to 25 inches; grayish brown (2.5Y 5/2) and light yellowish brown (2.5Y 6/4) clay which has a mottled appearance, very dark grayish brown (2.5Y 3/2) and light olive brown (2.5 5/4) moist; moderate coarse subangular blocky structure; very hard, very firm, sticky and very plastic; few very fine roots; many very fine and fine tubular pores; common thin clay films on faces of peds and lining pores; slightly acid (pH 6.5); clear smooth boundary. (2 to 7 inches thick).
Cr--25 to 40 inches; light yellowish brown (2.5Y 6/4) consolidated sediments, light olive brown (2.5Y 5/4) moist; massive; very hard, firm, sticky and plastic; few thin clay films in pores.
TYPE LOCATION: Alameda County, California; about 10 miles southeast of Pleasanton in the SE 1/4 SE 1/4 NW 1/4 of section 24, T. 4 S., R. 1 E., projected in the Valle de San Jose Land Grant.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 20 to 40 inches. The soil between depths of 4 and 12 inches becomes moist in some part in November or early December and remains moist until May. Mean annual soil temperature is about 59 to 63 degrees F. The solum includes up to 20 percent gravel by volume. It is moderately acid to neutral throughout.
The A horizon is 10YR 5/2, 4/2, 5/1, 4/1, 3/1; 2.5Y 5/2 and 4/2. Organic matter is more than 1.2 percent to a depth of more than 4 inches. Texture is typically clay loam but includes silt loam and silty clay loam.
The Bt horizon is 10YR 4/2, 5/2, 5/4; 2.5Y 4/2 and 5/2. It is clay or sandy clay.
The Cr horizon is 7.5YR 6/6; 10YR 6/4, 5/4; 2.5Y 5/4. It is consolidated gravelly fine textured sediments, and soft shale, or sandstone, and is slightly calcareous in some pedons.
COMPETING SERIES: These are the Rincon, Shoba (T), Skyhigh, Sleeper and Stomar (T) series. Rincon, Sleeper, and Stomar (T) are deeper than 40 inches. Shoba and Skyhigh soils have a lithic contact at 20 to 40 inches.
GEOGRAPHIC SETTING: Azule soils are on hills and have slopes of 9 to 75 percent. They formed from moderately fine textured consolidated alluvium and soft shale and fine grained sandstone. Elevations are 100 to 2,000 feet. The climate is subhumid mesothermal having warm, dry summers and cool, moist winters. Mean annual precipitation is 15 to 30 inches. Average January temperature is 48 degrees F; average July temperature is 68 degrees F; mean annual temperature is 59 to 62 degrees F. Frost-free season is about 250 to 320 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Rincon soils and the Altamount, Diablo, Hillgate, Pleasanton and Positas soils. Altamont and Diablo soils are clayey throughout, crack widely on drying and have intersecting slickensides. Hillgate, Pleasanton and Positas soils lack a paralithic contact. Hillgate and Positas soils also have an abrupt A-B horizon boundary.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: Used mainly as rangeland but fruit and grain are grown in some areas. Vegetation is mainly annual grasses, forbs and widely spaced valley oaks. Brush and blue oak have invaded some areas, particularly where erosion has occurred.
DISTRIBUTION AND EXTENT: Foothills of the intermountain and coastal valleys of the Coast Ranges of central California. The soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Clara Area, California, 1941.
REMARKS: The Azule soils were classified as a Noncalcic Brown-Prairie intergrade.