LOCATION VENADO CAEstablished Series
TAXONOMIC CLASS: Very-fine, magnesic, thermic Aridic Endoaquerts
TYPICAL PEDON: Venado silty clay, rangeland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 3 inches; very dark gray (2.5Y 3/1) clay, black (2.5Y 2.5/1) moist; strong fine angular blocky structure; very hard, firm, moderately sticky and very plastic; common very fine roots; neutral (pH 7.2); abrupt wavy boundary.
A--3 to 13 inches; very dark gray (2.5Y 3/1) clay, black (2.5Y 2.5/1) moist; weak very coarse prismatic parting to moderate very coarse angular blocky structure; very hard, firm, moderately sticky and very plastic; common very fine roots; very slightly effervescent; pressure faces on vertical and horizontal faces of peds; slightly alkaline (pH 7.8); gradual smooth boundary.
Bss--13 to 30 inches; black (2.5Y 2.5/1) clay, black (2.5Y 2.5/1) moist; strong moderate angular blocky structure parting to weak moderate wedge shaped aggregates; very hard, firm, moderately sticky and very plastic; few very fine roots; very slightly effervescent; many intersecting slickensides; 5 percent chert gravels; moderately alkaline (pH 8.0); clear smooth boundary.
Bk--30 to 38 inches; gray (5Y 6/1) silty clay, very dark gray (5Y 3/1) and olive gray (5Y 4/2) moist; weak medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; few fine tubular pores; few faint patchy clay films on vertical and horizontal faces of peds; strongly effervescent; strongly alkaline (pH 8.6); gradual smooth boundary.
Btk--38 to 53 inches; light olive gray (5Y 6/2) and pale yellow (5Y 8/2) silty clay loam, olive gray (5Y 4/2) and light olive gray (5Y 6/2) moist; weak fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine and common fine tubular pores; violently effervescent; few faint patchy clay films on vertical and horizontal faces of peds; strongly alkaline (pH 8.5); abrupt smooth boundary.
BCtk--53 to 61 inches; light olive gray (5Y 6/2) silty clay loam, dark olive gray (5Y 3/2); weak medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine and common fine tubular pores; strongly effervescent; few faint patchy clay films on vertical and horizontal faces of peds; strongly alkaline (pH 8.5); abrupt smooth boundary.
Ab--61 to 69 inches; very dark gray (2.5Y 3/1) clay, black (2.5Y 2.5/1) moist; strong fine angular blocky structure; very hard, firm, moderately sticky and very plastic; very slightly effervescent; pressure faces on vertical and horizontal faces of peds; moderately alkaline (pH 8.0).
TYPE LOCATION: Colusa County, California; about 3 1/2 miles southwest of Leesville; about 1100 feet west and 200 feet north of the southeast corner of section 17, T. 15 N., R. 5 W., MDB&M; 39 degrees, 8 minutes, 29.15 seconds north latitude and 122 degrees, 25 minutes, 53.58 seconds west longitude (derived by GPS); USGS Leesville, California topographic quadrangle.
RANGE IN CHARACTERISTICS: The soils have 1 to 2 cm wide cracks that open and close at least once each year and remain open for 180 days or more. Cracks open vertically to 50 cm. The mean annual soil temperature is 58 degrees to 60 degrees F. Coarse fragments range from 0 to 15 percent. Ca to Mg ratios are 1:5 to 1:11. The 6 to 20 inch SMCS is dry in all parts from June 1 to October 31 and moist in some or all parts from November 1 to May 31. The 10 to 40 inch textural control section weighted average clay content is 60 to 65 percent.
The Ap and A horizons colors are 10YR 4/1, 3/1; 2.5Y 3/1; moist colors are 10YR 2/1; 2.5Y 2.5/1. Texture is clay, silty clay or clay loam. Clay content ranges from 35 to 65 percent. Reaction is neutral to slightly alkaline.
The Bss and Bk horizons colors are 10YR 5/1, 3/1; 5Y 6/1; 2.5Y 2.5/1; moist colors are 10YR 3/1, 2/1; 5Y 4/2, 3/1; 2.5Y 2.5/1. Texture is silty clay or clay loam. Clay content ranges from 35 to 65 percent. Reaction is moderately to strongly alkaline.
The Btk and BCtk horizons colors are 10YR 5/2; 5Y 8/2, 6/2; 2.5Y 6/2 6/1; moist colors are 10YR 3/2; 5Y 6/2,4/2,3/2; 2.5Y 4/2,4/1. Texture is clay loam or loam. Clay content ranges from 25 to 40 percent clay. Reaction is strongly alkaline.
The Ab horizon has color of 5Y 3/1; 2.5Y 3/1; moist color of 5Y 2.5/1; 2.5Y 2.5/1. Texture is clay. Clay content ranges from 40 to 80 percent. Reaction is moderately alkaline.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Venado soils are in basins. Elevations are 1050 to 1350 feet. They formed in fine textured alluvium derived dominantly from serpentine minerals. Slopes are 0 to 2 percent. The climate is semiarid with hot, dry summers and cool moist winters. Mean annual precipitation ranges from 17 to 21 inches. Mean January temperature is 43 degrees F., mean July temperature is 76 degrees F, mean annual temperature ranges from 57 degrees to 61 degrees F. Frost-free season is 185 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Leesville(T) and Bearvalley(T) soils. Leesville soils have less than 35 percent clay in the series control section. Bearvalley soils have less than 27 percent clay and more than 35 percent coarse fragment in the series control section.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow runoff; slow permeability. Water tables occur at 2 to 3 feet in winter months. Drainage has been altered by down cutting of stream channels.
USE AND VEGETATION: Used for livestock grazing, irrigated pasture and small grains and alfalfa. Native vegetation is a dense stand of annual grasses and forbs.
DISTRIBUTION AND EXTENT: Intermountain valleys of the Coast Range of northern California. The soil is not extensive in MLRA-14.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Colusa County, California, 1997.
REMARKS:
ADDITIONAL DATA: UC Davis grab samples 1810-1 through 7.