LOCATION BUTTONWILLOW CAEstablished Series
TAXONOMIC CLASS: Clayey over loamy, smectitic, nonacid, thermic Vertic Torrifluvents
TYPICAL PEDON: Buttonwillow clay, on a nearly level slope of less than 1 percent. The field was in fallow at an elevation of 275 feet. (Colors are for dry soil unless otherwise stated. When described on 11/20/70 the soil was moist throughout.)
Ap--0 to 13 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; weak and moderate very coarse and medium prismatic structure; very hard, firm, very sticky and very plastic; many very fine roots; many very fine tubular pores; approximately 25 percent of faces of peds have slickensides; moderately alkaline (pH 8.2); clear wavy boundary. (8 to 13 inches thick)
A12--13 to 28 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; moderate very coarse prismatic structure; very hard, firm, very sticky and very plastic; few very fine roots; common very fine tubular and few very fine interstitial pores; approximately 10 percent of faces of peds have slickensides; moderately alkaline (pH 8.2); abrupt smooth boundary. (12 to 27 inches thick)
IIC1--28 to 45 inches; light gray (5Y 7/1) fine sandy loam, gray (5Y 5/1) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few very fine roots; common very fine tubular and many very fine interstitial pores; moderately alkaline (pH 8.0); abrupt smooth boundary. (14 to 22 inches thick)
IIC2--45 to 55 inches; gray (5Y 6/1) fine sandy loam, dark gray (5Y 4/1) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few very fine roots; common very fine tubular and many very fine interstitial pores; moderately alkaline (pH 8.0); abrupt smooth boundary. (14 to 22 inches thick)
IIIC3--55 to 64 inches; very dark gray (5Y 3/1) light clay, black (5Y 2.5/1) moist; common fine distinct light yellowish brown mottles (10YR 6/4) massive; very hard, firm, sticky and slightly plastic; few very fine roots; many very fine tubular pores; moderately alkaline (pH 8.2).
TYPE LOCATION: Kern County, California; about 2 miles south of Buttonwillow, 20 feet northwest of the corner of Brite Road and Wasco Way in the SE1/4 SE1/4 SE1/4 sec. 25, T.29 S., R. 23 E. MDB&M.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is about 65 degrees to 67 degrees F. The soil between the depths of about 4 and 12 inches is dry all the time from early in the spring to early in the winter and is moist for less than 90 consecutive days in all parts of the moisture control section during the winter. The clayey material overlying the loamy material is 20 to 35 inches thick.
The A horizon has dry color of 10YR 4/1, 4/2 or 5/1 and moist color of 10YR 2/1, 2/2, 3/1 or 3/2. It is typically clay but includes silty clay and silty clay loam. Clay percentage ranges from 35 to 55. Organic matter ranges from 1 to 3 percent to a depth of more than 20 inches and decreases irregularly with increasing depth. Surface cracks are 1 to 3 cm wide and 20 or more inches deep when dry and remain open for more than 240 days cumulative and are closed for less than 60 consecutive days. Slickensides occur on 5 to 30 percent of faces of peds but do not intersect. It is moderately alkaline (pH 7.9 to 8.4) but is noneffervescent.
The IIC horizon has dry color of 2.5Y 7/2, 6/2, 5/2; 5Y 7/1, 7/2, 6/1 or 6/2 and moist color of 2.5Y 3/2, 4/2; 5Y 3/2, 4/1, 4/2 or 5/1. It is sandy loam or fine sandy loam. Clay ranges from 8 to 15 percent. It is noneffervescent to strongly effervescent.
The IIIC horizon when present has dry color of 5Y 3/1 or 2.5Y 6/2 and moist color of 5Y 2/1, 3/1 or 2.5Y 3/2. When present, mottles are distinct or prominent. This horizon is heavy clay loam or clay and averages 35 to 50 percent clay.
COMPETING SERIES: These are the Guest, Lerdo, and Lokern series in other families. Ginland soils are effervescent throughout, are underlain by a buried B2t horizon and are intermittently moist in some part of the moisture control section during the summer. Guest soils have clay textures more than 40 inches thick and some parts of the moisture control section are intermittently moist during the summer. Lerdo soils are fine-loamy and are effervescent. Lokern soils have clay textures more than 40 inches thick.
GEOGRAPHIC SETTING: Buttonwillow soils are in basins and have slopes of 0 to 2 percent. The soils formed in alluvium from granitic rock sources. Elevations are 250 to 300 feet. The climate is arid (desert) with hot, dry summers and cool, somewhat moist winter. Mean annual precipitation is 5 to 7 inches. Summer rains are rare. Mean January temperature is 45 degrees F.; mean July temperature is 83 degrees F.; mean annual temperature is 63 degrees F. Frost-free season is about 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Lerdo and Lokern soils and the Milham and Garces soils. Milham and Garces soils have light colored surface horizons and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained, very slow runoff; slow permeability in the upper part of the textural control section, moderately rapid in the lower part, and slow below the control section. These soils are subject to rare flooding but are protected by dams and/or levees.
USE AND VEGETATION: Used mainly for irrigated crops such as alfalfa, barley, cotton, sorghum, and sugar beets. Natural vegetation consists of annual grasses, forbs, and saltbush (Atriplex spp.).
DISTRIBUTION AND EXTENT: Southern part of the San Joaquin Valley of California; the soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Kern County, Northwestern Part, California, 1982.
REMARKS: Buttonwillow soils have the necessary color and organic carbon to qualify as Mollisols but are not moist for 90 cumulative days.