LOCATION PISMO CAEstablished Series
TAXONOMIC CLASS: Mixed, thermic, shallow Typic Xeropsamments
TYPICAL PEDON: Pismo loamy sand, rangeland. (Colors are for dry soil unless otherwise noted.)
A11--0 to 1 inch; light brownish gray (10YR 6/2) loamy sand, very dark grayish brown (10YR 3/2) moist; weak very fine and fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine roots; common very fine interstitial and tubular pores; medium acid (pH 5.7); abrupt smooth boundary. (1 to 2 inches thick)
A12--1 to 14 inches; light brownish gray (10YR 6/2) loamy sand, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine roots; few very fine interstitial and tubular pores; medium acid (pH 5.7); gradual smooth boundary. (4 to 13 inches thick)
A13--14 to 19 inches; light brownish gray (10YR 6/2) loamy sand, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and nonplastic; common fine roots; common very fine and fine interstitial and tubular pores; medium acid (pH 5.7); abrupt wavy boundary. (3 to 5 inches)
Cr--19 to 22 inches; white (10YR 8/2) sandstone crushing easily to loamy sand, light yellowish brown (10YR 6/4) moist; many very fine roots in cracks which are less than 12 inches apart and less than 1mm wide; iron stains lining cracks; directly overlying the paralithic contact is a continuous 1/4 to 1/8 inch thick very dark brown (10YR 2/2) sandy clay loam band; medium acid (pH 5.7).
TYPE LOCATION: San Luis Obispo County, California; approximately 1.28 miles north and 4.2 miles west of the SE corner of sec. 24, T.32S., R.13E., MDB&M.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact of sandstone is 8 to 20 inches. The soil between the depths of 12 and 20 inches is usually moist from sometime in November to sometime in May and usually dry the rest of the year. The mean annual soil temperature is about 62 degrees to 65 degrees F. Organic matter is less than 1 percent below 1 to 4 inches. Texture throughout the soil profile is loamy sandy or sand. Reaction ranges from strongly acid through slightly acid. Base saturation is assumed to be greater than 60 percent in some part of the profile.
The A horizon is gray, grayish brown or light brownish gray (10YR 5/1, 5/2, 6/1, 6/2) dry, very dark gray, very dark grayish brown, dark gray or dark grayish brown (10YR 3/1, 3/2, 4/1, 4/2) moist.
Some pedons have a C horizon with a color of light brownish gray, pale brown, (10YR 6/2, 6/3, 7/2, 7/3) dry, dark brown, brown or pale brown (10YR 4/3, 6/3) moist.
The Cr horizon is very pale brown or white (10YR 7/3, 7/4, 8/2, 8/3) dry, pale brown or light yellowish brown (10YR 6/3, 6/4) moist and crushes easily to a loamy sand or sand. Reaction ranges from very strongly acid through medium acid. Most pedons have an accumulation of black sandy clay, clay, or silty clay which ranges from a thin film to 2 inches thick directly overlying the paralithic contact. Fractures in the parent material are less than 12 inches apart and the width of fractures is less than 1mm. Clay films and iron stains line the fractures. Fractures contain very fine and fine roots.
COMPETING SERIES: These are the Daulton, Exchequer, Gaviota, Millsholm and Temescal series in other families. These soils are loamy and have a lithic contact. Also Daulton soils are dark brown or dark grayish brown. Exchequer soils are very stony.
GEOGRAPHIC SETTING: Pismo soils are on uplands and have slopes of 9 to 75 percent. They formed in material weathered from soft sandstone at elevations from 25 to 700 feet. The climate is subhumid mesothermal with warm, dry but foggy summers and cool, moist winters. Mean annual precipitation is 15 to 22 inches. Average January temperature is 52 degrees F., average July temperature is 60 degrees F., mean annual temperature is 57 degrees to 60 degrees F. The frost-free season is 325 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arnold, Briones, San Andreas, Corralitos and Tierra soils and the competing Gaviota soils. Arnold soils are 40 to 60 inches deep. Briones soils are 20 to 40 inches deep. San Andreas soils have a mollic epipedon, are coarse-loamy and have a paralithic contact at a depth of 24 to 40 inches. Corralitos soils are formed in alluvium. Tierra soils are on marine terraces and have a fine textured argillic horizon.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; moderately rapid to very rapid runoff; rapid permeability.
USE AND VEGETATION: Used for range, wildlife habitat, watershed, and recreation. Natural vegetation is mainly brush with a sparse understory of annual grasses and forbs.
DISTRIBUTION AND EXTENT: Coastal foothills of San Luis Obispo County, California. The soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Luis Obispo County, Coastal Part, California, 1977.