LOCATION CONEJO CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Pachic Haploxerolls
TYPICAL PEDON: Conejo clay loam under a cover of milo at an elevation of 135 feet, (41 m). Re-described on 7/20/1993. (Colors are for dry soil unless otherwise noted).
Ap--0 to 5 inches, (0 to 13 cm); dark gray (10YR 4/1) clay loam, very dark gray (10YR 3/1) moist; 31 percent clay, moderate medium and coarse subangular blocky and strong medium granular structure; very hard, friable, moderately sticky and moderately plastic; many fine and medium irregular pores; slightly alkaline, pH 7.5 by Hellige-Truog; abrupt wavy boundary. (3 to 8 inches, (8 to 20 cm) thick)
A1--5 to 19 inches, (13 to 48 cm); very dark grayish brown (10YR 3/2) clay loam, very dark brown (10YR 2/2) moist; 31 percent clay, moderate coarse subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common very fine roots; many very fine and fine tubular and many fine irregular pores; slightly alkaline, pH 7.5 by Hellige-Truog; clear wavy boundary. (10 to 17 inches, (25 to 43 cm) thick)
A2--19 to 30 inches, (48 to 76 cm); very dark grayish brown (10YR 3/2) clay loam, very dark grayish brown (10YR 3/2) moist; 31 percent clay, moderate medium subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common very fine roots; many very fine and few fine tubular pores; few pressure faces; common fine iron-manganese nodules about l mm diameter; 1 percent gravel; slightly alkaline, pH 7.5 by Hellige-Truog; gradual wavy boundary. (10 to 15 inches, (25 to 38 cm) thick)
Bw1--30 to 48 inches, (76 to 122 cm); dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; 29 percent clay; moderate coarse subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common very fine roots; many very fine and fine tubular and many fine irregular pores; many pressure faces; few fine iron-manganese nodules about 1 mm diameter; 2 percent gravel; slightly alkaline, pH 7.5 by Hellige-Truog; clear wavy boundary. (13 to 20 inches, (33 to 51 cm) thick)
Bw2--48 to 70 inches, (122 to 178 cm); brown (10YR 5/3) loam, dark yellowish brown (10YR 4/4) moist; 19 percent clay, weak fine and medium subangular blocky structure; slightly hard, weakly brittle but friable, nonsticky and slightly plastic; common very fine roots; many very fine and few fine and medium tubular pores; slightly effervescent in seams; common medium oxidized iron masses; 1 percent gravel; moderately alkaline, pH 8.0 by Hellige-Truog.
TYPE LOCATION: Butte County, California; about 6 miles south of Chico on west side of Aquas Frias Road; 800 feet south of northeast corner of Section 33, Township 21 N., Range 1 E., 39 degrees, 38 minutes, 10 seconds North latitude; 121 degrees, 51 minutes, 40 seconds West longitude, NAD27 - U.S.G.S. Quad: Chico, California.
RANGE IN CHARACTERISTICS: Depth is greater than 80 inches, (203 cm). The mean annual soil temperature is 59 to 66 degrees F, (15 to 19 degrees C). The soil moisture control section is dry in all parts from about May through October (about 140 to 160 days). The particle-size control section has about 20 to 35 percent clay and some gravel is present.
Some pedons have fine sandy loam or loam overwash less than 20 inches (51cm) thick. These pedons have clay loam or loam Ab and upper Bw horizons, have 0 to 5 percent gravel and average 18 to 35 percent clay in the particle-size control section. The extent of this overwash phase is 600 to 700 acres and is the result of hydraulic mine deposits splaying out of the early levees on Butte Creek, north of Durham.
The Ap and A horizons have dry colors of 10YR 3/2, 4/1, 4/2, 4/3, 4/4, 5/2 or 5/3. Moist color is 10YR 3/1, 3/2, 2/2, 3/3, 4/2 or 7.5YR 3/2. In some pedons, it has weak to strong granular structure; in others, all or part has moderate to strong subangular blocky structure. Texture is clay loam. Clay content ranges from 27 to 35 percent. Organic matter ranges from 1.5 to 6 percent. Rock fragments range from 0 to 2 percent gravel. Reaction ranges from slightly acid to slightly alkaline.
The upper Bw horizon has dry colors of 10YR 4/2, 4/3, 4/4, 5/2, 5/3, 5/4, 6/2, 6/3, 6/4, 7/3, 7.5YR 4/2, 4/4, 5/4 or 6/4. Moist color is 10YR 2/2, 3/2, 3/3, 3/4, 4/2, 4/3, 4/4, 5/2, 7.5YR 3/2, 3/4, 4/2 or 4/4. Texture is loam or clay loam. Clay content ranges from 27 to 35 percent. Rock fragments range from 0 to 2 percent gravel. Reaction ranges from slightly acid to slightly alkaline.
The lower Bw horizon has dry colors of 10YR 3/4, 4/2, 4/3, 4/4, 5/3, 5/4, 6/2, 6/3, 6/4, 7.5YR 4/2, 4/4, 5/2 or 5/4. Moist color is 10YR 4/2, 4/3, 4/4, 5/3 or 5/4. Texture is sandy loam, fine sandy loam, loam or clay loam. Clay content ranges from 15 to 35 percent. Rock fragments range from 0 to 2 percent gravel. Reaction ranges from neutral to moderately alkaline, but some pedons are slightly acid. Segregated or secondary lime is in some pedons at depths greater than 48 inches, (76 cm). Some pedons have redoximorphic features within 40 inches, (102 cm) of the surface, a few pedons have redoximorphic features within 30 inches, (76 cm) of the surface. Some pedons have siltstone at depths of 40 to 60 inches, (102 to 152 cm).
COMPETING SERIES: These are the Agueda, Almendra, Anaheim, Carranza, Gazos, Reward, Salinas and Westfan series. Agueda soils are calcareous throughout. Almendra soils have 18 to 27 percent clay in the particle-size control section. Anaheim soils are moderately deep to a paralithic contact. Gazos soils have a lithic contact within 40 inches, (102 cm) of the surface. Carranza soils have extremely gravelly sandy clay loam C horizons within a depth of 40 inches, (102 cm). Reward soils are effervescent and have a lithic contact at 40 to 60 inches, (102 to 152 cm). Salinas soils have secondary carbonate accumulations in the C horizons. Westfan soils have Btk and Ck horizons that are strongly effervescent and have disseminated carbonates or concretions, have solum thickness of 25 to 60 inches, (64 to 152 cm), and have a water table between 36 to 60 inches, (91 to 152 cm) from November through April.
GEOGRAPHIC SETTING: Conejo soils are on alluvial fans and stream terraces at elevations of 30 to 2,000 feet, (9 to 610 m). Slopes range from 0 to 9 percent. The soil formed in alluvium from basic igneous and sedimentary rocks. The climate has hot dry summers and cool moist winters. Mean annual precipitation is 14 to 26 inches, (356 to 660 mm). Mean annual temperature is about 59 to 64 degrees F, (15 to 18 degrees C), average January temperature varies from 45 to 50 degrees F, (7 to 10 degrees C), and average July temperature varies from 70 to 80 degrees F, (21 to 26 degrees C). Frost free period is about 260 to 330 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cibo, Clear Lake and Trimmer soils. Cibo and Trimmer soils occur on upland areas and have lithic and paralithic contacts respectively. Clear Lake soils are of clay texture and occupy basins.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff, moderately slow saturated hydraulic conductivity in the A and upper Bw horizons and moderately slow to moderately rapid in the lower Bw horizon. Some areas are subject to occasional flooding.
USE AND VEGETATION: Used for irrigated row crops, orchard, hay and pasture and grain. Vegetation is annual grasses and forbs with few scattered oaks.
DISTRIBUTION AND EXTENT: Valley areas in northern and central California and the Coast Range of California. The soils are of small extent
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Siskiyou County (Shasta Valley Area, California 1919).
REMARKS: The Conejo series was established in Siskiyou County in 1919. The type location was moved to Butte County some time prior to 1989. It is mapped in multiple MLRA's in Butte, Contra Costa, Los Angeles, San Benito, Santa Cruz, Solano, Sutter and Yuba Counties.
The official description from Butte County was written prior to modern soil survey mapping and does not adequately represent conditions in Butte County. The type location was revisited on 7/93 and the description revised. The range of characteristics has been left as is. The use of Conejo in other areas should be reviewed during MLRA updates. In Butte County, to reflect actual conditions, the range of characteristics in the taxonomic unit description is narrowed down. (Average clay in the particle-size control section is 27 to 35 percent).
Additional Data: Clay determined by particle-size analysis at local survey office.