LOCATION YOKUT CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Typic Haploxeralfs
TYPICAL PEDON: Yokut sandy loam - on a slope of 1 percent in a fallow field at an elevation of 175 feet. (Colors are for dry
soil unless otherwise stated. When described on April 8, l980,
the soil was moist throughout.)
Ap--0 to 6 inches; yellowish brown (10YR 5/4) sandy loam, dark yellowish brown (10YR 4/4) moist; strong fine granular structure; slightly hard, friable, slightly sticky and slightly plastic;
common very fine and few fine roots; few very fine tubular pores;
1 percent gravel 2 to 5 mm in size; medium acid (pH 6.0); abrupt smooth boundary. (5 to 9 inches thick)
A--6 to 16 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; massive; hard, friable, slightly sticky and plastic; few very fine roots; few very fine and fine tubular pores; 1 percent gravel 2 to 5 mm in size; slightly acid
(pH 6.5); clear wavy boundary. (8 to 16 inches thick)
2BA--16 to 21 inches; light yellowish brown (10YR 6/4)
gravelly loam, strong brown (7.5YR 5/6) moist; massive; hard, friable, sticky and slightly plastic; few very fine roots; few
very fine and fine tubular pores; few thin clay films in pores; 25 percent gravel 2 to 5 mm and 20 to 75 mm in size; moderately
alkaline (pH 8.0); abrupt wavy boundary. (0 to 6 inches thick)
2Bt1--21 to 36 inches; strong brown (7.5YR 5/6) extremely
gravelly sandy clay loam, strong brown (7.5YR 4/6) moist; massive; hard, friable, sticky and plastic; few very fine and fine roots;
few very fine tubular pores; many moderately thick and thick clay films bridging sand grains and coating pebbles; 70 percent gravel
2 to 65 mm in size; moderately alkaline (pH 8.0); diffuse smooth boundary.
2Bt2--36 to 68 inches; strong brown (7.5YR 5/6) extremely
gravelly sandy clay loam, strong brown (7.5YR 4/6) moist; massive; hard, friable, sticky and plastic; no roots; few very fine tubular pores; many moderately thick and thick clay films bridging sand grains and coating pebbles; 70 percent gravel 2 to 75 mm in size; moderately alkaline. (pH 8.0). (Combined thickness of the 2Bt horizons extend to below 60 inches)
TYPE LOCATION: Merced County, California; about 4 miles west of
the city of Gustine, 2,500 feet east and 1,200 feet north of the
SW corner of section 10, T.8 S., R.8 S.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 59 degrees to 65 degrees F. The soil temperature is below 47 degrees
F in parts of January and February. It is not below 41 degrees F
at any time. The soil between 10 and 30 inches is moist in all
parts from January 1 to May 1 and dry in all parts from July 1 to October 31. Rock fragments range from 0 to 10 percent in the A horizon, from 20 to 30 percent in the 2BA horizon, and from 60 to
80 percent in the 2Bt horizon. Some pedons do not have a 2BA horizon. Organic matter is less than 1 percent in the A horizon.
The A and Ap horizons are 7.5YR 4/2, 4/4, 5/6; 10YR 4/2, 4/3, 5/4, 6/3 or 6/4. Moist colors are 7.5YR 3/2, 3/4; 10YR 3/2, 3/3, 3/4,
4/3 or 4/4. Some pedons are hard and massive when dry. Reaction
is medium acid to neutral. It is sandy loam or loam in the upper part and loam or sandy clay loam in the lower part. It has 12 to
25 percent clay content.
The 2Bt horizon is 7.5YR 4/2, 4/4, 5/4, 5/6, 6/4; 10YR 4/3, 4/4,
5/2, 5/4 or 6/4. Moist colors are 7.5YR 3/2, 3/4, 4/4, 4/6, 5/4, 5/6; 10YR 3/2, 3/3, 3/4, 4/3 or 4/4. It is extremely gravelly
loam, or extremely gravelly sandy clay loam with 20 to 30 percent clay content.
COMPETING SERIES: These are the
Peckham and
Yorba series in the
same family and the
Bally and Pleasonton Series in other families. Peckham soils have a lithic contact at a depth of 20 to 30 inches. Yorba soils have rock fragments throughout. Bally soils average
over 35 percent clay content in the texture control section. Pleasonton soils have over 0.7 percent organic carbon in the upper
4 inches of the surface horizon.
GEOGRAPHIC SETTING: Yokut soils are on flood plains and on
alluvial fan overwash over terraces with slopes of 0 to 2 percent. Elevations range from 120 to 1,400 feet. These soils formed in alluvium from igneous and sedimentary rock. The climate is
semiarid with hot dry summers and cool moist winters. The mean annual precipitation is 10 to 12 inches. The mean January temperature is 45 degrees F; the mean July temperature is 78
degrees F; and the mean annual temperature is 60 degrees to 64 degrees F. The frost-free season is 190 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Bapos,
Carranza,
Damluis,
Vernalis and
Woo soils. Bapos and Damluis soils have a
fine texture control section. Carranza and Woo soils have a
mollic epipedon, a fine-loamy texture control section, and do not have an argillic horizon. Vernalis soils are calcareous
throughout and have a fine-loamy texture control section.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for cropland and
rangeland. Among the crops grown are walnuts, oranges, almonds,
sugar beets and barley. The rangeland vegetation is soft chess, filaree, foxtail barley, foxtail fescue, clover, red brome and
other annual grasses and forbs.
DISTRIBUTION AND EXTENT: These soils are in small intermountain valleys in the foothills of the Coast Range of California and
along the western edge of the Central San Joaquin Valley. They
are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California 1984. Named after
the Yokut Indians of the San Joaquin Valley.
REMARKS: These soils were mapped as Mocho and Pleasonton in the
Los Banos Area, Series 1939 report. They are being differentiated
by having an argillic horizon, which is not typical of the Mocho series and by having less than 0.7 percent organic carbon in the upper 4 inches of the surface horizon which is not typical of the Pleasonton series. pH determined by colormetric method using
Thymol Blue and Hellige-Truog Triplex indicators. Texture
determined by hydrometer method. Organic matter estimated from adjacent soils where Walkley-Black digestion method was used.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 8 inches.
Argillic horizon - 21 to 68 inches(2Bt1, 2Bt2 horizons).
Particle-size control section - upper 20 inches of the Bt horizon.