LOCATION PEDCAT CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Aquic Natrixeralfs
TYPICAL PEDON: Pedcat loam - on a smooth slope of 1 percent in flat rangeland at 85 feet elevation. (Colors are for dry soil unless otherwise stated. When described on October 19, 1979, the soil was moist below 5 inches. This year was wetter than normal).
A--0 to 2 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; strong fine granular structure; soft, friable, slightly sticky and nonplastic; many very fine and common medium roots; common very fine interstitial pores; slightly acid (pH 6.1); abrupt smooth boundary.
E--2 to 5 inches; light brownish gray (10YR 6/2) and light yellowish brown (10YR 6/4) clay loam, dark grayish brown (10YR 4/2) and brown (10YR 4/3) moist; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine and medium roots; common very fine tubular pores; electrical conductivity is 11 decisiemens per meter; sodium adsorption ratio is 20; neutral (pH 6.8); abrupt smooth boundary. (Combined thickness of the A horizon is 0 to 7 inches)
Btn1--5 to 13 inches; dark grayish brown (10YR 4/2) and light yellowish brown (10YR 6/4) clay, very dark grayish brown (10YR 3/2) and dark brown (10YR 3/3) moist; strong medium prismatic structure; very hard, very firm, moderately sticky and very plastic; common very fine and few fine and medium roots; many very fine tubular pores; many thin pressure faces; many moderately thick clay films line pores; electrical conductivity is 10 decisiemens per meter; sodium adsorption ratio is 30; moderately alkaline (pH 8.0); clear irregular boundary. (6 to 9 inches thick)
Btn2--13 to 23 inches; grayish brown (10YR 5/2) and brownish yellow (10YR 6/6) silty clay, dark brown (10YR 3/3) and dark yellowish brown (10YR 4/4) moist; strong coarse angular blocky structure; very hard, very firm, moderately sticky and very plastic; few very fine and fine and common medium roots; common very fine tubular pores; many moderately thick pressure faces; many moderately thick clay films line pores; slightly effervescent, carbonates disseminated; electrical conductivity is 14 decisiemens per meter; sodium adsorption ratio is 43; moderately alkaline (pH 8.3); clear smooth boundary. (8 to 12 inches thick)
Btkn--23 to 29 inches; light yellowish brown (10YR 6/4) silty clay loam, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure, hard, firm, moderately sticky and very plastic; few very fine and medium roots; common very fine tubular pores, many thin pressure faces; many thin clay films line pores; slightly effervescent, carbonates disseminated and segregated as few fine irregularly shaped soft masses; electrical conductivity is 15 decisiemens per meter; sodium adsorption ratio is 50; few fine distinct light brown (7.5YR 6/4) redoximorphic masses of iron accumulation, few fine distinct brown (7.5YR 4/2) moist; strongly alkaline (pH 8.5); clear smooth boundary. (4 to 7 inches thick)
C1--29 to 42 inches; light yellowish brown (10YR 6/4) clay loam, brown (10YR 4/3) moist; weak moderate subangular blocky structure; hard, firm, moderately sticky and very plastic; few very fine roots; many very fine tubular pores; slightly effervescent, carbonates disseminated; strongly alkaline (pH 8.5); clear smooth boundary. (10 to 20 inches thick)
C2--42 to 60 inches; very pale brown (10YR 7/3) clay loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; hard, friable, moderately sticky and very plastic; few very fine roots; many very fine tubular pores; slightly effervescent, carbonates disseminated; strongly alkaline (pH 8.5).
TYPE LOCATION: Merced County, California; approximately 4.3 miles north of the community of Volta, 9 miles north of Los Banos, 2,600 feet northeast of the northwest corner of improved pasture; 1,500 feet east and 1,400 feet north of the southwest corner of section 12, T. 9 S., R. 9 E., MDB&M; Latitude 37 degrees, 09 minutes, 48 seconds north and Longitude 120 degrees, 56 minutes, 11 seconds west; USGS Ingomar Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: The moisture control section of 5 to 15 inches is moist throughout from about January 1 to June 1 and dry throughout from about July 15 to November 1. The soil temperature is warmer than 47 degrees F from January 20 to December 1. The mean annual soil temperature is 59 degrees to 65 degrees F. The A and Btn horizons have been mixed through cultivation in some pedons. In some pedons erosion has removed the entire A horizon. Organic matter is 1 percent or less and decreases with depth. Clay content in the Btn horizon is at least 1.2 times greater than that of the A horizon, except where the A horizon has been mixed with the Btn horizon or has been removed through erosion. Electrical conductivity is 0 to 16 decisiemens per meter. In some pedons, electrical conductivity has been significantly altered by human activities such as applications of soil amendments and irrigation water.
The A and E horizon have color of 10YR 4/2, 5/2, 5/3, 6/2, 6/3, 6/4, 7/1, 7/3, 7/4; or 2.5YR 6/2. Moist color is 10YR 2/2, 3/2, 3/3, 3/4, 4/2, 4/3, 5/3, 6/4; or 2.5YR 4/2. Some pedons have redoximorphic features that are few fine prominent 7.5YR 3/4 or 2.5Y 4/4 moist. Texture is fine sandy loam, loam or clay loam. Clay content is 12 to 38 percent. Calcium carbonate equivalent is 0 to 2 percent. Sodium adsorption ratio is 0 to 20. Reaction is slightly acid to slightly alkaline. Truncated soils have clay at surface.
The Btn and Btkn horizons have color of 7.5YR 6/4; 10YR 4/2, 4/3, 5/1, 5/2, 5/3, 5/4, 6/2, 6/3, 6/4, 6/6, 7/3; 2.5YR 6/4 or 7/2. Moist color is 7.5YR 4/4; 10YR 3/2, 3/3, 4/2, 4/3, 4/4, 5/3, 5/4; 2.5Y 4/2, 4/4 or 5/2. In some parts, redoximorphic features are few to common fine and medium prominent and have moist color of 7.5YR 3/2, 3/4, 4/2, 4/4, 4/6; 5Y 4/2, 5/1 or N 2/0. Where the moist chroma of the matrix is 2, redox features have chroma of 2 or less. Texture is sandy clay loam, clay loam, silty clay loam, clay or silty clay. Clay content is 20 to 50 percent and averages 35 to 50 percent in the upper part. Sodium adsorption ratio is 13 to 80, although parts of some pedons that have been modified by agricultural practices have sodium adsorption ratio as low as 2. Calcium carbonate equivalent is 0 to 15 and is 2 to 15 in Btkn horizons. Effervescence of disseminated carbonates is none to strongly effervescent in Btn horizons. Disseminated and segregated carbonates are slightly effervescent to violently effervescent in Btkn horizons. Reaction is moderately alkaline to very strongly alkaline. In some pedons, where a Btkn horizon is present, the Btn horizon is not present.
The C horizon has color of 7.5YR 6/6; 10YR 5/4, 6/3, 6/4, 6/6, 7/3, 7/4, 7/6, 8/6; 2.5Y 5/4, 6/4 or 7/4. Moist color is 7.5YR 4/4, 4/6; 10YR 4/3, 4/4, 4/6, 5/3, 5/4, 5/6, 6/4, 7/4; 2.5Y 3/2, 4/2, 4/4 or 5/2. In some pedons redoximorphic features are few to common, fine and medium distinct and prominent and have moist color of 7.5YR 3/2, 4/4, 5/4; 2.5Y 6/8, 7/4; 5Y 4/3, 6/1; 5GY 5/1, 6/1; 5G 5/1, 6/1; or 5BG 5/1. Texture is sandy clay loam, clay loam, silty clay loam, sandy clay or clay. Clay content is 30 to 45 percent. Calcium carbonate equivalent is 0 to 15 percent. Effervescence of disseminated carbonates is noneffervescent to violently effervescent. It is moderately alkaline or strongly alkaline. Some pedons have up to 10 percent brittle durinodes. In some pedons the C horizon is not present.
COMPETING SERIES: There are no competing series at this time.
GEOGRAPHIC SETTING: Pedcat soils are on low alluvial fans adjacent to the valley basin rim and fan remnants on foothill valleys. Slope is 0 to 5 percent. These soils formed in mixed alluvium derived mostly from sedimentary and/or metasedimentary rock. Elevation is 60 to 1,100 feet. The climate is semiarid with hot dry summers and cool moist winters. The mean annual precipitation is about 9 to 12 inches. Mean January temperature is 46 degrees F; mean July temperature is 79 degrees F; mean annual temperature is 60 to 64 degrees F. Frost-free season is 200 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Britto, Chateau, Marcuse, Pescadero, Santanella and Volta soils. Britto soils, on valley basin rims, are very poorly drained, have aquic moisture regimes, and have a smectitic mineralogy class. Chateau soils, on fan skirts and low alluvial fans, do not have a natric horizon. Marcuse soils, on valley basin rims, do not have a natric horizon and develop wide cracks upon drying. Pescadero soils, in basins, have a smectitic mineralogy class. Santanella soils, on valley basins, have a fine-loamy particle-size class and are very poorly drained. Volta soils, on valley basin rims, have a duripan at a depth of 45 to 55 inches.
DRAINAGE AND PERMEABILITY: Poorly drained; negligible to high runoff; very slow permeability. The water table is at a depth of 18 to 36 inches in December through March, unless artificially drained. Some areas, on fan remnants of foothill valleys, have a water table deeper than 6 feet. These areas are subject to ponding after periods of intense rainfall.
USE AND VEGETATION: These soils are used for livestock grazing and, where leveled, are used for irrigated pasture and crops, including barley, oats, alfalfa, corn, and sugarbeet.
DISTRIBUTION AND EXTENT: These soils occur in low alluvial fans and the basin rim of the Central San Joaquin Valley and in foothill valleys in the eastern part of the Diablo Range in the California Coast Ranges.s. They are moderately extensive. MLRA 17.
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 the Orestimba series. These soils are being differentiated by having an ochric epipedon and a clayey natric horizon.