LOCATION ZAKME CAEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, mesic Vertic Haploxerolls
TYPICAL PEDON: Zakme clay, annual range. (Colors are for dry soil unless otherwise noted.)
01--1 inch to 0; mat of leaves and twigs; partially decomposed; abrupt smooth boundary. (1/2 to 2 inches thick)
A11--0 to 3 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; strong medium and coarse granular structure; hard, firm, very sticky and very plastic; common very fine and few fine roots; many very fine and common fine tubular and interstitial pores; neutral (pH 7.0); gradual wavy boundary. (2 to 4 inches thick)
A12--3 to 14 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; moderate medium and coarse subangular blocky and weak coarse prismatic structure; very hard, very firm, very sticky and very plastic; common very fine roots; common very fine, fine and medium tubular pores; mildly alkaline (pH 7.5); gradual wavy boundary. (8 to 12 inches thick)
A13--14 to 22 inches; dark gray (10YR 4/1); clay, very dark gray (10YR 3/1) moist; weak coarse subangular blocky structure; very hard, very firm, very sticky and very plastic; common very fine and few fine, medium and coarse roots; common very fine, fine and medium tubular pores; 5 percent by volume weathered 3 to 5 mm shale fragments; mildly alkaline (pH 7.5); clear wavy boundary. (8 to 10 inches thick)
A1--22 to 36 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; massive; very hard, firm, very sticky and very plastic; common very fine and few fine, medium and coarse roots; many very fine and fine and few medium tubular pores; slightly effervescent with disseminated lime; mildly alkaline (pH 7.5); clear wavy boundary. (10 to 12 inches thick)
AC--36 to 47 inches; finely mixed dark gray (10YR 4/1) and light yellowish brown (10YR 6/4) clay, black (10YR 2/1) and dark yellowish brown (10YR 4/4) moist; massive; hard, firm, sticky and plastic; common medium and coarse roots; common fine and few medium tubular pores; strongly effervescent with disseminated lime; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 11 inches thick)
C1--47 to 55 inches; light yellowish brown (10YR 6/4) clay, dark yellowish brown (10YR 4/4) moist; massive; hard, friable, sticky and plastic, common medium and coarse roots; common fine and few medium tubular pores; strongly effervescent with disseminated lime; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 9 inches thick)
C2r--55 to 63 inches; very pale brown (10YR 7/4) soft; weathered, calcareous shale, yellowish brown (10YR 5/4) moist; strongly effervescent with disseminated lime; moderately alkaline (pH 8.0).
TYPE LOCATION: San Luis Obispo County, California; about 1-3/4 miles west on jeep road from entrance of Willow Creek Ranch; center of SW1/4 SW1/4 section 35, T.26S., R.10E.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 40 to 60 inches. The soil between depths of 4 and 12 inches becomes moist in some part of November or early December and remains moist until May, and is dry all the rest of the year. The mean annual soil temperature is 54 degrees to 57 F. Organic matter content is 1 to 4 percent to depth at least 20 inches and decreases regularly with increasing depth. Pebbles make up about 0 to 15 percent and cobbles about 0 to 10 percent of the profile, by volume. These fragments tend to be more numerous in the lower part of the profile. Reaction is neutral to moderately alkaline. From August to October the soil has cracks 1 to 4 cm wide at the surface and 1 cm wide at a depth of 50 cm. Some pedons have slickensides in the lower part of the A horizon, but not close enough to intersect. Clay minerals are dominantly montmorillonitic, and average more than 60 percent of the fine earth fraction in the 10- to 40-inch control section.
The A1 horizon is gray, dark gray, grayish brown or dark grayish brown (10YR 5/1, 4/1, 5/2, 4/2).
The AC horizon is finely mixed gray, dark gray, grayish brown or dark grayish brown (10YR 5/1, 4/1, 5/2, 4/2) and light brownish gray, pale brown or light yellowish brown (10YR 6/2, 6/3, 6/4).
The C1 horizon is light brownish gray, pale brown or light yellowish brown (10YR 6/2, 6/3, 6/4). It is clay or silty clay.
COMPETING SERIES: These are the Ayar, Diablo, Gazos, Linne, Santa Lucia and Zaca series in similar families. Ayar and Diablo soils average less than 60 percent clay, slickensides close enough to intersect, and have cracks 1 cm wide and that are open in most years to a depth of 50 cm. Gazos and Linne soils have less than 35 percent clay in the textural control section. Santa Lucia soils have more than 35 percent, by volume, rock fragments 2 mm or larger in the textural control section. Zaca soils average less than 60 percent clay and have a mean annual soil temperature of about 60 degrees F.
GEOGRAPHIC SETTING: The Zakme soils are on rolling and steep uplands. They formed in material weathered from calcareous shales and fine grained sandstone. The parent material is highly weathered. Elevations are 1,000 to 2,000 feet. The climate is subhumid with cool wet winters and warm dry summers. Mean annual precipitation is 16 to 25 inches. Average January temperature is 44 degrees to 46 degrees F.; average July temperature is 60 degrees to 63 degrees F.; the mean annual temperature is 53 degrees to 57 degrees F. The annual freeze-free season is 225 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Ayar, Diablo, and Linne soils and the Calodo, Los Gatos, Los Osos and Nacimiento soils. Calodo soils are less than 20 inches deep to a paralithic contact. Los Gatos and Los Osos soils have B2t horizons with less than 50 percent clay. Nacimiento soils have less than 35 percent clay in the textural control section.
DRAINAGE AND PERMEABILITY: Well drained; medium and rapid runoff; low permeability.
USE AND VEGETATION: Used mostly for grazing, recreation, wildlife habitat and watershed. A few areas have been cleared and cultivated for dry farmed barley and almonds. Vegetation is Coast live oak, California laurel, and white oak and an understory of scrub oak, toyon, poison oak and annual grasses. Crown canopy cover is 30 to 50 percent.
DISTRIBUTION AND EXTENT: South-central and southern part of Coast Range in California. The soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Luis Obispo County (Paso Robles Area), California, 1977.
OSED scanned by SSQA. Last revised by state on 2/77.