LOCATION ANTIOCH CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Natrixeralfs
TYPICAL PEDON: Antioch loam - plowed field (Colors are for dry soil unless otherwise noted.)
Ap--0 to 5 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; common fine yellowish brown (10YR 5/6) mottles, strong brown (7.5YR 5/6) moist; massive; hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine roots; many very fine and medium tubular pores; medium acid (pH 5.6); clear smooth boundary. (5 to 10 inches thick)
A1--5 to 14 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; few fine yellowish brown (10YR 5/6) mottles, strong brown (7.5YR 5/6) moist massive; hard, friable, slightly sticky, slightly plastic; few very fine roots; many fine and medium acid (pH 6.0); clear wavy boundary. (8 to 15 inches thick)
A2--14 to 19 inches; light gray (10YR 7/2) loam, dark grayish brown (10YR 4/2) moist; common fine yellowish sticky, slightly sticky; slightly plastic; few very fine roots; many fine pores; Mn stains; slightly acid (ph 6.5); abrupt smooth boundary. (1/4 to 5 inches thick)
Bt1--19 to 34 inches; light yellowish brown (10YR 6/4) clay, dark yellowish brown (10YR 3/3) moist; moderate very coarse prismatic structure; extremely hard, very firm, sticky, very plastic; few very fine roots; common very fine tubular pores; many moderately thick clay films on faces of peds and lining pores; few dark stains; medium acid (pH 6.0); clear wavy boundary. (9 to 16 inches thick)
Bt2--34 to 37 inches; yellowish brown (10YR 5/4) heavy clay loam, dark brown (10YR 4/3) moist; weak medium angular blocky structure; extremely hard, very firm, sticky, plastic; common very fine tubular pores; many moderately thick clay films on faces of peds and lining pores; many dark stains; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 14 inches thick)
Bt3--37 to 46 inches; pale brown (10YR 6/3) clay loam, dark yellowish brown (10YR 4/4) moist, dark brown (7.5YR 3/2) and dark grayish brown (2.5Y 4/2) ped faces moist; weak medium angular blocky structure; hard, firm, sticky, plastic; common very fine tubular pores; continuous moderately thick clay films on faces of peds and lining pores; common dark stains; moderately alkaline (ph 8.0); diffuse boundary. (0 to 10 inches thick)
Bt4--46 to 60 inches; pale brown (10YR 6/3) silty clay loam, olive brown (2.5Y 4/2) and dusky red (2.5YR 3/2) faces of peds moist; weak medium angular blocky structure; hard, firm, sticky, plastic; common very fine tubular pores; continuous moderately thick clay films on faces of peds and lining pores; common dark stains; moderately alkaline (ph 8.0); clear wavy boundary. (0 to 14 inches thick)
C1--60 to 76 inches; pale brown (10YR 6/3) loam, dark yellowish brown (10YR 4/4) moist; weak medium angular blocky structure; slightly hard, friable, slightly sticky, plastic; many very fine tubular pores; common thin clay films on faces of peds and lining pores; common dark stains; moderately alkaline (pH 8.0); clear wavy boundary. (10 to 20 inches thick)
C2--76 to 81; Dark yellowish brown (10YR 4/4) moist fine sandy loam; weak medium angular blocky structure; slightly hard, friable, many very fine tubular pores; few thin clay films on faces of peds and lining pores; moderately alkaline (ph 8.0); common Fe and Mn stains.
TYPE LOCATION: Solano County, California; 1 1/2 miles east of Suisun City; SW1/4 SE1/4 SW1/4 sec. 29, T. 5 N., R. 1 W., MDB&M 38 degrees North latitude 14 minutes, 40 seconds, 122 degrees West longitude 00 minutes, 5 seconds.
RANGE IN CHARACTERISTICS: The mean annual soil temperature 59 to 64 F. The soils become moist in some or all parts between depths of 4 to 12 inches about late November and usually remain moist all the time until late May or early June. The soils remain dry all rest of the time. Few pebbles are present throughout the some pedons. Coarse and very coarse sand is less than 5 percent.
The A1 horizon is dark grayish brown, dark brown, brown, grayish brown, or light brownish gray. It contains more than 1 percent organic matter in the upper 10 inches, but is hard and massive when dry. This horizon is neutral to strongly acid, though neutral saturation in some pedons.
The A2 horizon is gray, light brownish, light brownish gray or light gray and is slightly to strongly acid. The A2-Bt horizon boundary is abrupt or very abrupt. The Bt horizon is dark brown, yellowish brown, light yellowish brown and pale brown 10YR hue and light olive brown and light yellowish brown in 2.5Y hue. It is medium acid to moderately alkaline, becoming more alkaline with increasing depth. All of the Bt horizon has more than 15 percent exchangeable sodium. It is clay or heavy clay loam and has approximately 35 to 45 percent clay. It has weak or moderate columnar moderate to strong prismatic structure in the upper part. Usually there are transitional horizons to the C horizon. The lower Bt horizons or B3 or C horizons are calcareous in some or all parts.
The C horizon is pale brown, light yellowish brown, yellowish brown or dark yellowish brown, it is somewhat stratified and is usually clay loam or loam in texture. This horizon is mildly or moderately alkaline.
COMPETING SERIES: These are the Bonsall, Las Flores, Lethent, Milipitas, Placentia, Riz, San Miguel, Solano, Stockpen, Tierra, and Waukena series. Bonsall and Stockpen soils lack an albic horizon. Las Flores, Milipitas, and Tierra soils lack natric horizons. Lethent soils have an aridic moisture regime. Placentia soils have about 15 to 20 percent coarse and very coarse sand in the B2t horizon. Riz soils lack an abrupt A-B horizon boundary with more than 15 percent absolute clay difference. San Miguel soils have a lithic contact at depth of 20 to 34 inches. Solano and Waukena soils have less than 35 percent clay in the natric horizon.
GEOGRAPHIC SETTING: Antioch soils are on nearly level to strongly sloping alluvial fans and terraces at elevations of less than 1,100 feet. Slopes are usually less than 3 percent. The climate is subhumid mesothermal with warm to hot dry summers and cool moist winter. Mean annual precipitation is 12 to 20 inches. Average January temperature is about 46 F, average July temperature about 68 F, mean annual temperature about 58 F, and the freeze-free season ia about 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Altamont, Los Osos, Pleasanton, Rincon, and San Ysidro soils and the competing Solano soils. Altamont soils are of fine texture throughout and have cracks. Los Osos soils have mollic epipedons. Pleasanton, Rincon, and San Ysidro soils lack natric horizons.
DRAINAGE AND PERMEABILITY: Moderately well to somewhat poorly drained; slow to medium runoff; very slow permeability.
USE OF VEGETATION: Used for production of annual pasture, dryfarmed grain and some irrigated row crops. Vegetation in untilled areas is annual grasses, forbs and weeds with scattered oaks.
DISTRIBUTION AND EXTENT: Along the central and southern Coast Range valleys in California. They are of moderate extent in MLRA 14 and 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Reconnaissance of Sacramento Valley, California, 1913.
REMARKS: The soils were formerly classified in the solodized-Solonetz group. Soils of the Huerhuero series are now included with the Antioch series.
Last revised by the state on 5/72.
ADDITIONAL DATA: NSSL pedon S64CA-095-008 (type location) and S78CA-000-000 (range in characteristics).