LOCATION TACHI CAEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, thermic Typic Natraquerts
TYPICAL PEDON: Tachi clay - on a slope of less than one percent in a wheat field at 159 feet elevation. (Colors are for dry soil unless otherwise stated). When described on December 11, 1980, the soil was slightly moist below 5 inches and moist below 22 inches.
Ap1--0 to 5 inches; very dark gray (5Y 3/1) clay, black (5Y 2/1) moist; strong medium subangular blocky structure; very hard, firm, very sticky and very plastic; many very fine and few fine roots; few very fine tubular and common very fine interstitial pores; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped soft masses; electrical conductivity is 1.3 decisiemens per meter; sodium adsorption ratio is 4; moderately alkaline (pH 8.0); abrupt smooth boundary. (3 to 9 inches thick)
Ap2--5 to 14 inches; dark gray (5Y 4/1) clay, black (5Y 2/1) moist; strong coarse prismatic structure; very hard, firm, very sticky and very plastic; many very fine and few fine roots; common very fine tubular and interstitial pores; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped soft masses; electrical conductivity is 3.7; sodium adsorption ratio is 12; moderately alkaline (pH 7.9); abrupt wavy boundary. (5 to 12 inches thick)
Bknssg1--14 to 22 inches; variegated dark gray (5Y 4/1) and olive gray (5Y 5/2) clay, variegated black (N 2/0) and black (5Y 2/1) moist; strong very coarse prismatic structure; very hard, firm, very sticky and very plastic; common very fine roots; common very fine interstitial pores; common intersecting slickensides; few fine irregularly shaped dark reddish brown (5YR 3/4) concretions moist; strongly effervescent, carbonates disseminated and segregated as common fine irregularly shaped soft masses; electrical conductivity is 2.4 decisiemens per meter; sodium adsorption ratio is 14; few fine prominent red (2.5YR 4/6) moist redoximorphic masses of iron accumulation; moderately alkaline (pH 8.0); abrupt wavy boundary. (7 to 14 inches thick)
Bknssg2--22 to 28 inches; variegated dark gray (5Y 4/1) and olive gray (5Y 5/2) clay, variegated black (N 2/0) and very dark gray (5Y 3/1) moist; weak medium prismatic structure; very hard, firm, very sticky and very plastic; few very fine and fine roots; few very fine tubular pores; many intersecting slickensides; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped soft masses; electrical conductivity is 2.2; sodium adsorption ratio is 13; common fine prominent strong brown (7.5YR 5/6) and black (N 2/0) moist redoximorphic masses of iron and manganese accumulation; strongly alkaline (pH 8.6); abrupt smooth boundary. (4 to 6 inches thick)
Bknssg3--28 to 35 inches; variegated dark gray (5Y 4/1) and light gray (5Y 7/1) clay, gray (5Y 5/1) moist; massive; very hard, friable, very sticky and very plastic; few very fine roots; few very fine tubular pores; common intersecting slickensides; slightly effervescent, carbonates segregated as few fine irregularly shaped soft masses; electrical conductivity is 2.0; sodium adsorption ratio is 16; many medium prominent black (N 2/0) and strong brown (7.5YR 5/6) moist redoximorphic masses of iron and manganese accumulation; strongly alkaline (pH 8.9); clear wavy boundary. (4 to 8 inches thick)
Bkng1--35 to 47 inches; gray (5Y 5/1) clay, very dark gray (5Y 3/1) moist; massive; extremely hard, friable, very sticky and very plastic; few very fine tubular pores; many pressure faces; strongly effervescent, carbonates disseminated and segregated as common fine irregularly shaped masses; electrical conductivity is 2.8 decisiemens per meter; sodium adsorption ratio is 26; common fine prominent olive (5Y 4/4), few fine prominent gray (5Y 6/1) and common fine distinct black (N 2/0) moist redoximorphic masses of iron and manganese accumulation; strongly alkaline (pH 8.6); abrupt wavy boundary. (10 to 22 inches thick)
Bkng2--47 to 63 inches; dark gray (5Y 4/1) clay, variegated dark gray (5Y 4/1) and very dark gray (5Y 3/1) moist; massive; very hard, friable, very sticky and very plastic; few very fine tubular pores; many pressure faces; strongly effervescent, carbonates disseminated and segregated as common fine irregularly shaped soft masses and threads; electrical conductivity is 3.2 decisiemens per meter; sodium adsorption ratio is 34; few fine prominent yellowish red (5YR 4/6) moist redoximorphic masses of iron accumulation; strongly alkaline (pH 9.0); abrupt smooth boundary. (10 to 26 inches thick)
Bkng3--63 to 70 inches; variegated gray (5Y 6/1), dark gray (5Y 4/1) and light olive gray (5Y 6/2) clay, variegated dark gray (5Y 4/1) and very dark gray (5Y 3/1) moist; common fine prominent reddish yellow (7.5YR 6/6), yellowish red (5YR 4/6) moist, and few fine distinct black (5Y 2/1) mottles moist; massive; very hard, friable, sticky and very plastic; few very fine tubular pores; many pressure faces; violently effervescent, carbonates disseminated and segregated as common medium irregularly shaped soft masses; electrical conductivity is 4.6 decisiemens per meter; sodium adsorption ratio is 39; common fine prominent reddish yellow (7.5YR 6/6), yellowish red (5YR 4/6) and few fine distinct black (5Y 2/1) moist redoximorphic masses of iron and manganese accumulation; strongly alkaline (pH 8.8).
TYPE LOCATION: Fresno County, California, in the Mendota Wildlife Management Area; 120 feet north of a road and 180 feet west of a road; approximately 1,420 feet east and 120 feet north of the southwest corner of sec. 22, T. 14 S., R. 15 E., MDB&M; Latitude 36 degrees, 41 minutes, 25 seconds north and Longitude 120 degrees, 19 minutes, 36 seconds west; USGS Tranquillity Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: The soil is saturated in some or all parts at some time of the year. The mean annual soil temperature is 63 to 65 degrees F. It is typically saline-sodic in some part of the profile. When the soil is dry, vertical cracks extend from the surface to a depth of 20 to 40 inches and are 1 to 6 inches wide.
The Ap horizon has color of 5Y 3/1, 4/1 or 5/2. Moist color is 5Y 2/1, 2/2, 3/1 or N 2/0. Organic matter content is 1 to 3 percent. Clay content is 60 to 75 percent. Calcium carbonate equivalent is 1 to 2 percent. Electrical conductivity is 1 to 4 decisiemens per meter. Sodium adsorption ratio is 2 to 20. There are redoximorphic features in the lower part of the A horizon in some pedons. If chroma is 1.5 or higher, there are distinct or prominent redoximorphic features.
The Bknssg horizon has color of 5Y 4/1, 5/1, 5/2, 6/1, 6/2, 7/1 or 10YR 7/2. Moist color is 5Y 2/1, 3/1, 3/2, 4/1, 4/2, 5/1, 5/2, 5/3, 5/4, 6/3; 2.5Y 4/2; 10YR 4/2 or N 2/0. Organic matter content is 0.5 to 1 percent. Clay content is 60 to 75 percent. Intersecting slickensides occur throughout. Calcium carbonate equivalent is 1 to 3 percent. Electrical conductivity is 2 to 4 decisiemens per meter. Sodium adsorption ratio is 13 to 25. If chromas are 1.5 or higher, there are distinct or prominent redoximorphic features.
The Bkng horizon has color of 5Y 4/1, 5/1, 5/2, 6/1, 6/2, 7/1 or 10YR 7/2. Moist color is 5Y 2/1, 3/1, 3/2, 4/1, 4/2, 5/1, 5/2, 5/3, 5/4, 6/3; 2.5Y 4/2; 10YR 4/2 or N 2/0. Organic matter is 0.4 to 0.8 percent. Texture is clay or silty clay. Clay content is 40 to 70 percent. Calcium carbonate equivalent is 1 to 5 percent. Electrical conductivity is 2 to 8 decisiemens per meter. Sodium adsorption ratio is 13 to 50.
COMPETING SERIES: There are no competing series at this time.
GEOGRAPHIC SETTING: Tachi soils are on flood plains on basin floors. Slope is 0 to 1 percent. These soils formed in alluvium derived from igneous and/or sedimentary rock. Elevation is 120 to 210 feet. The climate is arid with dry, hot summers and mild, somewhat moist winters. The mean annual precipitation is 7 to 8 inches. Mean January temperature is about 44 degrees F; mean July temperature is about 81 degrees F; mean annual temperature is 62 to 65 degrees F. The frost-free season is 220 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Armona, Gepford, Lillis and Tranquillity series. Armona soils, on flood plains on basin floors, have a fine-loamy particle-size control section. Gepford soils, on flood plains on basin floors, have a fine particle-size control section. Lillis soils, on fan skirts, have a salic horizon and an ochric epipedon. Tranquillity soils, on fan skirts, have a fine particle-size control section.
DRAINAGE AND PERMEABILITY: Very poorly drained; high runoff; very slow permeability. The water table has been lowered to 4 to 6 feet by artificial drainage measures such as dam construction, levees and canals.
USE AND VEGETATION: These soils are used for irrigated crops such as cotton and seed alfalfa. These soils are also used for wildlife habitat and recreation on the Mendota Wildlife Management Area. Vegetation consists primarily of swamp Timothy and watergrass.
DISTRIBUTION AND EXTENT: Near the edge of the San Joaquin River and Fresno Slough in the San Joaquin Valley, California. They are moderately extensive. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Fresno County, California, 2002. Tachi soils are named after an American Indian tribe in the area.
REMARKS: Previously mapped as Merced clay in the Soil Survey of the Mendota Area, California, Series 1940, No. 18. Merced soil is not in the Vertisol taxonomic order. An area, of Tachi soils was mapped on the Eastern Fresno Area Soil Survey during the soil survey work on the Fresno County, Western Part Soil Survey. This area is adjacent to the eastern edge of the Fresno Slough and is both north and south of Whitesbridge Road (Highway 180). Personal communication with the late Dr. Gordon Huntington, indicated that this area was flooded when the soil survey work on the Eastern Fresno Area was in progress. This mapping has been incorporated into the digital SSURGO certified product for the Eastern Fresno Area Soil Survey.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - (not necessary for this taxonomic class) - 0 to 14 inches (Ap horizon).
Common to many intersecting slickensides and many pressure faces occur in the typical pedon between the depths of 14 to 35 inches.
ADDITIONAL DATA: The Bknssg1, Bknssg2 and Bknssg3 horizons in the typical pedon, sample number S80CA019-001 (827419-827421) have some data determined by the National Soil Survey Laboratory, Lincoln, Nebraska. This data is not currently available through the NSSC website.