LOCATION STANISLAUS CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Haploxerolls
TYPICAL PEDON: Stanislaus clay loam, on a slope of 1 percent in cultivated field at an elevation of 175 feet. (Colors are for dry soil unless otherwise stated. When described on November 1, 1979, the soil was slightly moist to 12 inches and moist below 12 inches.)
Ap1--0 to 11 inches; dark grayish brown (10YR 4/2) clay loam, dark brown (10YR 3/3) moist; strong very coarse and medium subangular blocky clods; very hard, friable, sticky and very plastic; few very fine roots; few very fine tubular pores; 38 percent clay content; EC is 1.9 mmhos/cm; ESP is 7; moderately alkaline (pH 8.0); abrupt smooth boundary.
Ap2--11 to 15 inches; dark brown (10YR 3/3) clay loam, dark brown (10YR 3/3) moist; strong coarse subangular blocky structure; very hard, friable, sticky and very plastic; few very fine roots; few very fine tubular pores; 1.29 percent organic matter; moderately alkaline (pH 8.0); abrupt smooth boundary. (Combined thickness of the Ap is 9 to 16 inches.)
A--15 to 19 inches; dark brown (10YR 3/3) clay loam, dark brown (10YR 3/3) moist; strong medium subangular blocky structure; very hard, friable, sticky and very plastic; few very fine roots; few very fine tubular pores; moderately alkaline (pH 8.0); clear smooth boundary. (2 to 4 inches thick)
Bt1--19 to 30 inches; dark brown (10YR 3/3) and brown (10YR 4/3) clay, very dark grayish brown (10YR 3/2) and dark brown (10YR 3/3) moist; strong medium subangular blocky structure; very hard, friable, sticky and very plastic; few very fine roots; few very fine tubular pores; 0.7 percent organic matter; 42 percent clay content; many thin clay films in pores; continuous thin pressure faces; 1 percent pebbles, 2 to 5 mm in size; moderately alkaline (pH 8.0); clear wavy boundary.
Bt2--3 to 39 inches; brown (10YR 4/3 and dark brown 10YR 3/3) clay, dark brown (10YR 3/3) and very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; very hard, friable, sticky and very plastic; few very fine roots; few very fine tubular pores; many thin clay films in pores; many thin pressure faces; moderately alkaline (pH 8.0); clear smooth boundary. (Combined thickness of the B2t is 13 to 22 inches thick)
Btk1--39 to 48 inches; yellowish brown (10YR 5/6) and dark yellowish brown (10YR 4/4) clay loam, dark yellowish brown (10YR 4/6) moist; weak medium subangular blocky structure; very hard, friable, sticky and plastic; few very fine roots; few very fine tubular pores; 36 percent clay content; common thin pressure faces; 10 percent calcium carbonate equivalent; slightly effervescent with disseminate lime and segregated as common fine rounded filaments and soft masses; moderately alkaline (pH 8.0); clear wavy boundary. (7 to 12 inches thick)
Btk2--48 to 65 inches; yellowish brown (10YR 5/6) clay loam, dark yellowish brown (10YR 4/6) moist; moderate medium subangular blocky structure; very hard, very friable, sticky and plastic; no roots; common very fine tubular pores; many thin pressure faces; 10 percent calcium carbonate equivalent; slightly effervescent with disseminated lime and segregated as common fine rounded filaments and soft masses; moderately alkaline (pH 8.0). (Combined thickness of the Btk is 24 more than 36 inches thick.)
TYPE LOCATION: Merced County; about 4.5 miles southwest of the city of Gustine, 120 feet east of the Delta-Mendota Canal. 1.7 miles north of Taglio Road. 1,600 feet north and 550 feet west of the SE corner of section 22, T.8S., R.8E.
RANGE IN CHARACTERISTICS: The soil between a depth of 6 to 16 inches is moist throughout from about January 15 to June 1 and dry throughout from July 15 through November 15. The soil temperature is warmer than 47 degrees F from January 15 to December 1. The mean annual soil temperature is 62 degrees F. The clay content of the A horizon ranges from 35 to 40 percent and the clay content of the Bt1 and Bt2 horizon ranges from 38 to 45 percent but is always less than 1.2 times more than the A horizon. The Btk horizon ranges from 25 to 40 percent clay content. Surface cracks range from 1 to 4 cm but are less than 1 cm wide within 20 inches of depth. Organic matter ranges from 1 to 2 percent but is less than 1 percent within 20 inches. Disseminated lime may start at 25 inches of depth but all segregated lime is below 36 inches. ESP is less than 8.
The A and AP horizon dry color is 10YR 3/3, 4/2, 4/3, 5/2, 5/3, or 5/4. Moist colors are 10YR 2/2, 3/2 or 3/3. It may have up to 10 percent gravel, 5 to 20 mm in diameter. The EC is less than 2 mmhos/cm and the reaction is mildly or moderately alkaline.
The Bt1 and Bt2 horizon dry color is 10YR 3/2, 3/3, 4/3, 5/4, 5/6, or 6/4. Moist colors are 10YR 3/2, 3/3, 3/4, 4/2, 4/3, 4/4, 4/6, or 5/4. It is clay loam or clay . It has moderate or strong subangular blocky structure. The reaction is mildly or moderately alkaline.
The Btk horizon dry color is 10YR 3/3, 4/3, 4/4, 4/6, 5/4, 5/6, 5/8 or 7.5YR 5/6. Moist colors are 10YR 3/6, 4/3, 4/4, 4/6, 4/8, 5/3, 5/4 or 7.5YR 4/4. Mottles, occurring only in the wet phase, are N 2/0, N 3/0; or 10YR 2/1. Typically, it is loam or clay loam but may be clay in the upper part. It is slightly or strongly effervescent but calcium carbonate equivalent is less than 15 percent. The reaction is mildly or moderately alkaline.
COMPETING SERIES: These are the Deldota, Myers, Rincon, Sorrento, Stomar (T), Vernalis, and Woo series in other families. Deldota soils develop wide cracks when dry and are somewhat poorly drained. Myers soils have wide cracks and slickensides. Rincon soils have a massive A horizon and an argillic horizon. Sorrento, Vernalis, and Woo soils have a fine, loamy control section. Stomar soils have an argillic horizon and an ochric epipedon.
GEOGRAPHIC SETTING: Stanislaus soils are on alluvial fans adjacent to the valley basin rim. These soils are formed in mixed alluvium dominantly from sedimentary rock sources. They are on nearly level topography. Elevations are 70 to 300 feet. The climate is semiarid, with hot, dry summers and cool, moist winters. The mean annual precipitation is about 9 to 12 inches. The mean annual temperature is about 63 degrees F.; the mean January temperature is 79 degrees F.; and the mean July temperature is 79 degrees F. The frost free season is 210 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Deldota, Sorrento, Stomar (T), and Woo soils and the Damluis, Dosamigos, and San Emigdio soils. Damluis soils have an argillic horizon. Dosamigos soils are somewhat poorly drained, have mottles within 20 inches of the surface, and are saturated with water for 90 days unless artificially drained. San Emigdio soils are coarse, loamy.
DRAINAGE AND PERMEABILITY: Well drained (some areas are now wet because of irrigation, with a water table at depth of 54 to 60 inches from April through October); slow runoff; slow permeability.
USE AND VEGETATION: These soils are leveled land used for irrigated truck crops, field crops, orchards, and hay crops.
DISTRIBUTION AND EXTENT: These soils occur on alluvial fans of the Central San Joaquin Valley adjacent to the Coast Range foothills. They are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California, 1984.
REMARKS: These soils were formerly included with and mapped as Rincon soils in the Los Banos Area, series 1939 report and the Stomas soils in the W. Stanislaus Area survey by the University of California 1968. pH determined by colorimetric method using Thymol Blue and Hellige-Truog Triplex indicators. Texture determined by modified Bouyoucos method. Presence of lime determined by 10 percent HCl solution. Calcium carbonate equivalent determined by field kit. Organic matter determined by Walkley-Black digestion method.