LOCATION ONEIL CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Calcic Haploxerolls
TYPICAL PEDON: Oneil silt loam - on a northeast facing slope of 31 percent under soft chess, filaree, and red brome at an elevation of 960 feet. (Colors are for dry soil unless otherwise stated. When described on June 14, 1979, the soil was dry throughout.)
A1--0 to 3 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores; slightly effervescent with disseminated carbonates and segregated as few fine irregular hard masses; 3.0 percent organic matter; moderately alkaline (pH 8.0); clear smooth boundary.
A2--3 to 6 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, sticky and plastic; common very fine tubular pores; slightly effervescent with disseminated carbonates; 1.6 percent organic matter; moderately alkaline (pH 8.3) clear smooth boundary.
A3--6 to 13 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak medium and coarse angular blocky structure; hard, friable, sticky and plastic; common very fine roots; few very fine tubular pores; strongly effervescent with disseminated carbonates 1.0 percent organic matter; moderately alkaline (pH 8.4); clear smooth boundary. (The combined thickness of the A horizon is 10 to 20 inches)
AC--13 to 21 inches; brown (10YR 5/3) silt loam, dark yellowish brown (10YR 4/4) moist; weak medium and coarse subangular blocky structure; hard, friable, sticky and slightly plastic; few fine roots; few very fine tubular pores; strongly effervescent with disseminated carbonates and segregated as common fine threads; 0.8 percent organic matter; moderately alkaline (pH 8.4); clear smooth boundary. (5 to 8 inches thick)
Ck--21 to 29 inches; yellowish brown (10YR 5/4) silt loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, sticky and plastic; few very fine roots; few very fine tubular pores; 6 percent gravel; strongly effervescent with disseminated carbonates and segregated as common fine threads; calcium carbonate equivalent is 14 percent; moderately alkaline (pH 8.4); abrupt wavy boundary. (5 to 13 inches thick)
R--29 to 33 inches; unweathered calcareous sandstone and shale.
TYPE LOCATION: Merced County, California; about 12 miles WSW of Los Banos, about 1/2 mile NW of B.M. 881 on Billie Wright Road, 2,400 feet west and 250 feet north of the SE corner of section 2, T. 11 S., R. 8 E. (projected section lines from section 6, T. 11 S., R. 9 E.) 36 degrees North latitude, 51 minutes, 55 seconds, 121 degrees West longitude, 2 minutes, 50 seconds.
RANGE IN CHARACTERISTICS: Depth to a lithic contact ranges from 20 to 40 inches. The soil between the depths of 4 and 12 inches is moist throughout from about December 1 to May 1 and dry throughout from about July 1 to November 1 most years. The soil temperature is warmer than 47 degrees F. from January 30 through December 1. The mean annual soil temperature is about 59 to 62 degrees F. Particle-size control section averages 20 to 35 percent clay content and 45 to 66 percent silt content and less than 15 percent coarser than very fine sand. Twenty five to 50 percent of the surface has been removed by erosion.
The A horizon is 10YR 3/3, 4/3, 4/4 or 5/3. Moist colors are 10YR 3/2 or 3/3. Texture is silt loam or silty clay loam. The clay content ranges from 20 to 35 percent and the silt content ranges from 50 to 70 percent. Organic matter ranges from 1 to 3 percent. Typically is slightly effervescent but ranges from slightly to strongly effervescent.
The Ck horizon is 10YR 5/4, 5/6 or 6/4. Moist colors are 10YR 3/3, 3/4, 4/3, 4/4 or 5/4. Texture is silt loam or silty clay loam. The clay content ranges from 20 to 35 percent and the silt content ranges from 50 to 70 percent. Calcium carbonate equivalent ranges from 5 to 14 percent. Gravel content ranges from 5 to 10 percent.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: Oneil soils are formed in material weathered from sandstone and shale in rolling to steep foothills. Elevations range from 200 to 1,400 feet. The climate is semiarid with hot dry summers and cool moist winters. The mean annual precipitation is about 10 to 12 inches. Mean January temperature is 45 degrees F.; mean July temperature is 77 degrees F.; and mean annual temperature is 59 to 64 degrees F. Frost-free season is 200 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: The Apollo, Arburua, Ayar, Bapos, and Los Banos and Wisflat soils. Apollo soils are fine-loamy and are 40 to 60 inches deep to a paralithic contact. Arburua soils are fine-loamy. Ayar soils are fine with more than 40 percent clay. Bapos soils have a fine textured argillic horizon and an abrupt A/B boundary. Los Banos soils have a fine textured argillic horizon. Wisflat soils are coarse-loamy and 10 to 20 inches deep to sandstone or shale.
DRAINAGE AND PERMEABILITY: Well drained, medium or high runoff, moderately slow permeability.
USE AND VEGETATION: These soils are used as rangeland. The vegetation is soft chess, wild oats, red brome, filaree, tarweed and other annual grasses and forbs. This also used for non-irrigated small grain crops and annual hay crops.
DISTRIBUTION AND EXTENT: These soils are in the Coast Range foothills bordering the western edge of the Central San Joaquin Valley of California. They are moderately extensive in MLRA 15.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED. Merced County. California 1984.
REMARKS: These soils were formerly mapped as Kettleman soils in the Los Banos Area, series 1939 report, being differentiated by having a Xeric moisture regime and a fine-silty control section. Texture, organic carbon, and pH (1:1 water) determined by National Soil Survey Laboratory in Lincoln, Nebraska. Presence of carbonates determined in field by 10 percent HC1 solution. Calcium carbonate equivalent determined by HC1 and double syringe kit.
Rapid runoff terminology adjusted 10/96 to new notation of medium or high, to comply with adjective criteria of the Soil Survey Manual, 10/93.
OSED scanned by SSQA. Last revised by state on 10/96.
ADDITIONAL DATA: NSSL pedon S9CA-047-004 (type location)