LOCATION OMNI CA
Established Series
Rev: WFA/GMK/LCL/ET
01/2023
OMNI SERIES
The Omni series consists of very deep, poorly drained soils that formed in mixed sediments. Omni soils are on level concave basins. The mean annual precipitation is 17 inches and the mean annual temperature is 58 degrees F.
TAXONOMIC CLASS: fine, smectitic, calcareous, thermic Fluvaquentic Endoaquolls
TYPICAL PEDON: Omni silty clay - irrigated row crops. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 12 inches; gray (10YR 5/1) silty clay, very dark gray (10YR 3/1) moist; weak coarse prismatic structure; very hard, firm, sticky, plastic; many very fine and medium and common coarse roots,; many very fine and medium tubular pores; common fine pale yellow(5y 7/3) and red (2.5YR 4/8) concretions; very slightly effervescent with lime segregated in a few fine soft masses; moderately alkaline (pH 8.2); abrupt wavy boundary. (8 to 20 inches thick)
B21cag--12 to 21 inches; gray (5Y 6/1) silty clay, olive gray (5Y 4/2) moist; gray (N 5/) faces of peds, very dark gray (5Y 3/1) moist; many medium distinct mottles of olive (5Y 4/3) moist; medium coarse prismatic structure that parts to medium coarse angular blocky structure; very hard, firm, sticky, plastic; many very fine and medium roots; many very fine and fine and common medium tubular and vesicular pores; thick discontinuous very dark gray (N 3/) bands of organic matter, black (N 2/) moist; few irregularly shaped soft masses of gypsum; strongly effervescent with lime in seams and filaments; moderately alkaline (pH 8.4); abrupt wavy boundary. (8 to 14 inches thick)
B22g--21 to 27 inches; gray (5Y 6/1) heavy clay loam, very dark gray (5Y 3/1) moist; many medium distinct mottles, very dark grayish brown (2.5Y 3/2) moist; moderate coarse prismatic structure that parts to moderate coarse angular blocky structure; very hard, friable, sticky, plastic; many very fine and fine roots; many very fine and fine tubular pores; many light yellowish brown (2.5Y 6/4) and few fine red (2.5YR 4/8) soft masses moist; slightly effervescent with disseminated lime; moderately alkaline(pH 8.4); abrupt wavy boundary. (5 to 10 inches thick)
A11bg--27 to 34 inches; mottled black (5Y 2/1), gray (5Y 5/1), light olive gray (5Y 6/2) and olive (5Y 5/4) silty clay, mottled black (5Y 2/1), very dark gray (5Y 3/1) and olive (5Y 4/4) moist; moderate medium prismatic structure that parts to moderate medium angular blocky structure; very hard, friable, slightly sticky, plastic; many very fine and fine roots; many very fine, fine and medium tubular pores; very slightly effervescent with disseminated lime; moderately alkaline (pH 8.3); abrupt wavy boundary. (6 to 14 inches thick)
A12bg--34 to 42 inches; mottled very dark gray (N 3/), dark gray (5Y 4/1), and pale olive (5Y 6/4) silty clay, mottled black (5Y 2/1), very dark gray (5Y 3/1), dark gray (5Y 4/1) and olive (5Y 4/3) moist; massive; very hard, firm, sticky, plastic; many very fine and fine roots; many very fine, fine and medium tubular pores; very slightly effervescent with disseminated lime; moderately alkaline (pH 8.2); abrupt smooth boundary. (6 to 14 inches thick)
IIC--42 to 45 inches; mottled light olive gray (5Y 6/2), pale olive (5Y 6/3) and light brownish gray (2.5Y 6/2) light clay loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; many very fine and fine roots; common very fine and fine tubular pores; common fine reddish yellow (5YR 6/6) soft masses, red (2.5YR 4/8) moist; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 4 inches thick)
IIIA1bg--45 to 48 inches; mottled dark gray (5Y 4/1) and pale yellow (5Y 7/3) silty clay, mottled very dark gray (5Y 3/1), dark gray (5Y 4/1) and olive gray (5Y 4/2) moist; massive; extremely hard, firm, slightly sticky, very plastic; many very fine and fine roots; many very fine and fine tubular pores; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 4 inches thick)
IIIACb3g--48 to 60 inches; similar to the two preceding horizons occurring in alternate bands. (1 to 4 inches thick)
TYPE LOCATION: Yolo County, California; 1.75 mile west of Clarksburg; .4 mile northeast of Clarksburg Road and main canal, and .15 mile west of S.N.R.R.
RANGE IN CHARACTERISTICS: The soils are usually moist throughout unless drained and not irrigated. Mottles and matrix chroma of 1 or 2 occur within 20 inches of the surface. Drained areas generally have a water table between depths of 20 and 48 inches. The soils are generally calcareous in all parts. The mean soil temperature is about 61 degrees F. All or some of the upper part of the profile shows stratification and the organic matter decreases irregularly with depth.
The A horizon ranges from gray to grayish brown and olive gray in hue of 10YR, 2.5Y, 5Y or neutral and has mottles in the lower part in some pedons. It is silty clay loam or clay. This horizon has about 2 percent organic matter. It is blocky or prismatic.
The B2 horizon ranges from light gray and gray to pale olive and light olive gray in hue of 5Y, 2.5Y or neutral. The B2 horizon and the 10 to 40 inch zone average silty clay or clay. They are moderately or strongly alkaline and have accumulations of lime in upper portions that decrease with depth. Many soft masses and concretions of pale yellow (5Y 7/3) to red (2.5YR 4/8) are typical in the lower portion of the horizon being more pronounced in some pedons than in others.
The C horizon, if present, is mottled in hue of 5Y or 2.5Y with chroma of I to 3. It ranges from light clay loam to silty clay. Lime may or may not be present. The buried horizons are typically stratified in color and texture.
COMPETING SERIES: These are the
Alamo,
Alviso,
Bayshore,
Castro,
Egbert,
Glann,
Maria,
Merritt,
Reyes,
Sacramento,
Sunnyvale,
Tyndall, and
Valdez series. Alamo soils have duripans. Alviso and Egbert soils are not calcareous in the 10 to 20 inch section. Bayshore, Castro, and Sunnyvale soils have horizons of marked lime Accumulation or calcic horizons. Glann, Maria, Reyes, Tyndall, and Valdez soils lack mollic epipedons; all but Reyes have less than 35 percent clay. Merritt soils have less than 35 percent clay. Sacramento soils have mollic epipedons more than 20 inches thick that are noncalcareous.
GEOGRAPHIC SETTING: Omni soils are in nearly level concave basin areas at elevations of 5 to 150 feet. The sediments are of mixed origin. The climate is dry subhumid, mesothermal with hot dry summers and cool moist winters. Mean annual rainfall is 17 to 18 inches. Mean annual temperature is 58 degrees F., average January temperature about 42 degrees F., and average July temperature about 75 degrees F. Frostfree season averages about 265 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Clear Lake,
Merritt,
Rincon,
Sycamore,
Tyndall, and
Willows soils. Clear Lake and Willows soils are less wet and have slickensides. Rincon soils are on higher positions in the landscape and have argillic horizons. Sycamore soils have less than 35 percent clay and are hard and massive in the A horizon.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow to slow runoff; slow permeability. Depth to water table ranges from 24 to 48 inches.
USE AND VEGETATION: Irrigated row and field crops are the principal uses.
DISTRIBUTION AND EXTENT: The soils are in basin areas in the lower Sacramento Valley in central California. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Yolo County, California, 1971.
REMARKS: Omni soils would have been classified as Humic Gley soils.
The classification was updated in February 2001 using the Eighth Edition to Soil Taxonomy. This series was formerly classified as fine, smectitic, calcareous, thermic Fluvaquentic Haplaquolls. Competing series were not checked at that time.
National Cooperative Soil Survey
U.S.A.