LOCATION LERDO CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, thermic Typic Torrifluvents
TYPICAL PEDON: Lerdo clay loam - on a southwest-facing slope of less than 1 percent under cultivation at 255 feet elevation. (Colors are for dry soil unless otherwise stated. When described on 4/4/73, the soil was moist throughout.)
Ap--0 to 7 inches; gray (10YR 5/1) clay loam, very dark gray (10YR 3/1) moist; moderate coarse and medium angular blocky structure; hard, firm, sticky and plastic; many very fine roots; many very fine interstitial and tubular pores; slightly effervescent, disseminated lime; moderately alkaline (pH 8.2); abrupt smooth boundary. (6 to 11 inches thick)
A12--7 to 22 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; weak coarse angular blocky structure; slightly hard, firm, sticky and plastic; common very fine and few fine roots; many very fine interstitial and tubular pores; slightly effervescent, disseminated lime; moderately alkaline (pH 8.2); clear smooth boundary. (14 to 17 inches thick)
C1--22 to 50 inches; light gray (10YR 6/1) loam, dark grayish brown (10YR 4/2) moist; weak medium prismatic and moderate coarse angular blocky structure; slightly hard, firm, sticky and plastic; common very fine and few fine roots; many very fine and common fine tubular pores; strongly effervescent, disseminated lime; strongly alkaline (pH 8.8); abrupt smooth boundary. (3 to 28 inches thick)
C2ca--50 to 60 inches; light gray (10YR 7/1) loam, pale brown (10YR 6/3) moist; massive; very hard, friable, slightly plastic; few very fine and fine roots; many very fine interstitial and many very fine and few fine tubular pores; few thin clay films in pores; violently effervescent, disseminated lime; strongly alkaline (pH 9.0).
TYPE LOCATION: Kern County, California; about 10 1/2 miles north of Buttonwillow and about 50 feet northeast of the southwest corner of the southwest 1/4, southeast 1/4, northwest 1/4 of section 11, T. 28 S., R. 23 E., MDB&M.
RANGE IN CHARACTERISTICS: The soil between depths of 4 and 12 inches is dry in all parts from April 1 until December 1 and is moist in some or all parts for 50 to 90 consecutive days during the winter. It is not moist for as long as 90 cumulative days. Mean annual soil temperature is 66 degrees F. and is always above 47 degrees F. Saline-alkali phases are recognized. The soil is moderately or strongly alkaline (pH 7.8-9.0).
The A horizon has dry color of 10YR 5/1 or 5/2 and moist color of 10YR 3/1 or 3/2. Organic matter ranges from 1 to 3 percent to a depth of more than 20 inches and decreases irregularly with increasing depth. It is heavy loam, clay loam, or silty clay loam and averages 25 to 35 percent clay. The EC is less than 3.0 mmhos/cm and the ESP is less than 11.
The C horizon has dry color of 10YR 5/1, 6/1, 6/2, 7/2; 2.5Y 6/2, 7/1 or 7/2 and moist color of 10YR 3/1, 4/2, 5/3, 6/3; 2.5Y 4/2 or 5/2. It is loam or light clay loam and is weakly stratified. Clay content is 20 to 30 percent. The C horizons have an EC of 1 to 8, but average 6 mmhos/cm and the ESP ranges from 1 to more than 70 but averages 30.
COMPETING SERIES: These are the Leeds and Rosamond series and the Glendale, Pima, and Westhaven series in another family. Glendale soils have less than 1 percent organic matter in the A horizon and are fine-silty. Pima soils are fine-silty. Leeds soils have 5YR or 2.5YR hue in the C horizon. Rosamond soils have less than 1 percent organic matter in the A horizon. Westhaven soils are fine-silty.
GEOGRAPHIC SETTING: Lerdo soils are on alluvial plains and basins. Slopes are 0 to 2 percent. The soils formed in alluvium from granite, shale, or sandstone. Elevations are 235 to 275 feet. The climate is arid with hot, dry summers and cool, somewhat moist winters. Summer rains are rare. Mean annual precipitation is 5 or 6 inches. Mean January temperature is about 46 degrees F., mean July temperature is about 83 degrees F., mean annual temperature is 63 degrees to 65 degrees F. Frost-free season is 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buttonwillow, Garces, Kimberlina, Lokern, Milham, Panoche, and Jerryslu soils. Buttonwillow soils are clayey over loamy. Garces and Milham soils have an argillic horizon. Kimberlina soils are coarse-loamy. Lokern soils are fine. Panoche soils have an organic carbon content that decreases regularly with increasing depth. Jerryslu soils have a duripan and a natric horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately slow permeability. These soils are subject to rare flooding but are protected by dams and/or levees. The drainage of these soils has been altered.
USE AND VEGETATION: Used mainly for irrigated crops such as alfalfa, barley, cotton, grain sorghum, sugar beets, and wheat. The choice of crops is governed by the degree of reclamation that has taken place. Natural vegetation consists of annual grasses, forbs, and saltbush.
DISTRIBUTION AND EXTENT: The southern part of the San Joaquin Valley of California. The soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Kern County, Northwestern Part, California, 1982.
REMARKS: This soil is not classified as a Mollisol because the epipedon is not moist for 90 cumulative days in 7 out of 10 years when not irrigated. It would be classified as a Mollic Torrifluvent if this subgroup were adopted.
The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET