LOCATION WEKODA CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Aquic Haploxererts
TYPICAL PEDON: Wekoda clay - on a slope of less than 1 percent in a rice field at an elevation of 115 feet. (Colors are for dry soil unless otherwise stated. When described on March 23, l977, the soil was moist throughout.)
Ap--0 to 5 inches; dark gray (5Y 4/1) clay, dark olive gray (5Y 3/2) moist; strong coarse and medium angular blocky structure; very hard, firm, moderately sticky and very plastic; many very fine and common fine roots; few very fine tubular pores; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 8 inches thick)
A--5 to 11 inches; dark gray (5Y 4/1) clay, dark olive gray (5Y 3/2) moist; strong coarse and medium angular blocky structure; very hard, firm, moderately sticky and very plastic; few very fine roots; few very fine tubular pores; strong intersecting slickensides at bottom of horizon; electrical conductivity is 3.4 decisiemens per meter; sodium adsorption ratio is 6.5; slightly effervescent, carbonates disseminated; common fine distinct yellowish brown (10YR 5/6) moist recent redoximorphic masses of iron accumulation; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 12 inches thick)
Bss--11 to 14 inches; olive gray (5Y 4/2) clay, dark olive gray (5Y 3/2) and olive brown (2.5Y 4/4) moist; strong coarse and medium angular blocky structure; extremely hard, firm, moderately sticky and very plastic; few very fine roots; few very fine tubular pores; intersecting slickensides throughout horizon; sodium adsorption ratio is 6; slightly effervescent, carbonates disseminated; moderately alkaline (pH 8.0); abrupt wavy boundary. (2 to 10 inches thick)
Bkss--14 to 22 inches; olive (5Y 5/3) clay, olive brown (2.5Y 4/4) moist; strong coarse and medium angular blockystructure; extremely hard, firm, moderately sticky and very plastic; no roots; few very fine tubular pores; intersecting slickensides throughout horizon; electrical conductivity is 5.4 decisiemens per meter, sodium adsorption ratio is 5; slightly effervescent, carbonates disseminated and segregated as common medium irregularly shaped soft masses; moderately alkaline (pH 8.0); clear wavy boundary. (6 to 15 inches thick)
Bky--22 to 62 inches; olive (5Y 5/3) clay, olive brown (2.5Y 4/4) moist; massive; extremely hard, firm, moderately sticky and very plastic; few very fine tubular pores; common medium irregularly shaped soft gypsum crystals; electrical conductivity is 7 decisiemens per meter; sodium adsorption ratio is 10; slightly effervescent, carbonates disseminated and segregated as few fine irregularly shaped soft masses; moderately alkaline (pH 8.0).
TYPE LOCATION: Merced County, California; approximately 3.5 miles south of the city of Dos Palos; 450 feet west and 300 feet north of the southeast corner of section 20, T. 11 S., R. 12 E., MDB&M; Latitude 36 degrees, 57 minutes, 13 seconds north and Longitude 120 degrees, 40 minutes, 19 seconds west; USGS Dos Palos Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: The soil between 6 and 18 inches is moist in all parts from January 1 to May 15 and dry in all parts from July 1 to November 1. Cracks range from 2 to 8 cm wide at the surface and are 1 cm wide to a depth of 20 to 30 inches from May 15 to November 15 where not irrigated. Intersecting slickensides occur in the lower A and in the Bss horizons. Redoximorphic features occur within 40 inches of the soil surface. In some pedons, redoximorphic features occur throughout the soil profile.
The A horizon has color of 2.5Y 5/2; 5Y 5/1, 4/1 or 4/2. Moist color is 2.5Y 3/2 or 5Y 3/2. Organic matter content is 1 to 3 percent. Clay content is 50 to 60 percent. Electrical conductivity is less than 4 decisiemens per meter. The sodium adsorption ratio is 1 to 10.
The B horizon has color of 2.5Y 4/2, 5/4, 6/4; 5Y 4/2 or 5/3. Moist color is 2.5Y 3/2, 4/4, 5/4; 5Y 3/2 or 4/3. Clay content is 45 to 60 percent. Electrical conductivity is 2 to 8 decisiemens per meter. The sodium adsorption ratio is 1 to 12. Gypsum crystals occur in some part.
COMPETING SERIES: This is the Oswald and Whitecabin (T) series. Oswald soils (MLRA 17), on basins and basin rims, have a paralithic contact at a depth of 20 to 40 inches. Whitecabin (T) soils (MLRA 22), on uplifted basins, have a duripan at a depth of 40 to 60 inches.
GEOGRAPHIC SETTING: Wekoda soils are on flood plains and basin floors in the valley. Slope is 0 to 2 percent. These soils formed in mixed alluvium derived dominantly from sedimentary rock. Elevation is 110 to 185 feet. The climate is semiarid with hot dry summers and cool moist winters. The mean annual precipitation is 8 to 12 inches. The mean January temperature is 46 degrees F; mean July temperature is 79 degrees F; and mean annual temperature is 60 to 64 degrees F. The frost-free season is 210 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Britto, Chateau, Dospalos, Elnido, Marcuse, Triangle, Trulae and Turlock soils. Britto and Turlock soils, on valley basin rims, have a natric horizon. Chateau soils, on fan skirts and low alluvial fans, have mixed mineralogy class and do not develop wide cracks when dry. Dospalos soils, on valley basins, do not have intersecting slickensides. Elnido soils, on flood plains, basin floors and valley basins, have a coarse-loamy particle-size control section. Marcuse Triangle and Trulae soils, on valley basin rims and valley basins, are saline-sodic.
DRAINAGE AND PERMEABILITY: Poorly drained; low to medium runoff; very slow permeability. A seasonal high water table is at a depth of 18 to 30 inches in December through March. The water table is at a depth of 30 to 72 inches during the remainder of the year. It is subject to brief periods of ponding after prolonged storms in December through February.
USE AND VEGETATION: These soils are used for cropland. The main crop is rice but sugar beets and barley are also grown.
DISTRIBUTION AND EXTENT: These soils are located along the western edge of the Central San Joaquin Valley of California. They are moderately extensive. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California 1984. Name is coined.
REMARKS: These soils were mapped as Lethent series in the Los Banos Area, California, 1939 Series Report. They are being differentiated by having an aquic moisture regime and not having a natric horizon.