LOCATION POSOCHANET CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Sodic Haplocambids
TYPICAL PEDON: Posochanet clay loam, on a slope of less than 1 percent in a wheat field at 256 feet elevation. (Colors are for dry soil unless otherwise stated. When described on 07/22/87 the soil was dry from 0 to 7 inches, slightly moist between 7 and 24 inches and moist from 24 to 60 inches).
Ap1--0 to 7 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; coarse strong subangular blocky structure parting to moderate subangular blocky; very hard, friable, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine and fine tubular pores; slightly effervescent, carbonates disseminated; electrical conductivity is 1.6 decisiemens per meter; sodium adsorption ratio is 2; moderately alkaline (pH 7.9); abrupt smooth boundary. (6 to 10 inches thick)
Ap2--7 to 15 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; slightly effervescent, carbonates disseminated; electrical conductivity is 3.6 decisiemens per meter; sodium adsorption ratio is 9; moderately alkaline (pH 8.0); clear smooth boundary. (7 to 10 inches thick)
Bw--15 to 24 inches; light yellowish brown (2.5Y 6/4) clay loam, olive brown (2.5Y 4/4) moist; weak coarse subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine and few fine tubular pores; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped seams and soft masses; electrical conductivity is 10.2 decisiemens per meter; sodium adsorption ratio is 30; moderately alkaline (pH 8.1); clear smooth boundary. (8 to 10 inches thick)
Bknz1--24 to 34 inches; light yellowish brown (2.5Y 6/4) clay loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and few fine tubular pores; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped seams and soft masses; electrical conductivity is 16.7 decisiemens per meter; sodium adsorption ratio is 42; moderately alkaline (pH 8.3); abrupt wavy boundary. (8 to 12 inches thick)
Bknz2--34 to 41 inches; light yellowish brown (2.5Y 6/4) clay loam, olive brown (2.5Y 4/4) moist; massive; hard; friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and fine tubular pores; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped seams and soft masses; electrical conductivity is 17.6 decisiemens per meter; sodium adsorption ratio is 39; moderately alkaline (pH 8.2); abrupt wavy boundary. (5 to 17 inches thick)
Bknz3--41 to 60 inches; pale yellow (2.5Y 7/4) loam, olive brown (2.5Y 4/4) moist; massive, slightly hard, friable, slightly sticky and moderately plastic; few very fine and fine roots; many very fine and few fine tubular pores; slightly effervescent, carbonates disseminated and segregated as common fine irregularly shaped seams and soft masses; electrical conductivity is 14.5 decisiemens per meter; sodium adsorption ratio 31; moderately alkaline (pH 8.2).
TYPE LOCATION: Fresno County, California; approximately 150 feet east of Jameson Ave., 1.5 miles west of Lemoore Naval Air Station; approximately 2640 feet south and 150 feet east of the northwest corner of section 2, T. 19 S., R. 18 E., MDB&M; Latitude 36 degrees, 18 minutes, 23 seconds north and Longitude 119 degrees, 59 minutes, 35 seconds west; USGS Vanguard Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 64 to 67 degrees F. The soil temperature is always above 47 degrees F.
The A horizon has color of 2.5Y 6/1 or 6/2. Moist color is 2.5YR 4/1 or 4/2. Organic matter content is 0.5 to 2 percent. Texture is silt loam, silty clay loam or clay loam. Clay content is 18 to 40 percent. Calcium carbonate equivalent is 0 to 5 percent. It is noneffervescent to violently effervescent. Gypsum content is 0 to 5 percent. Carbonates and gypsum content has been affected by irrigation. Electrical conductivity is 0 to 8 decisiemens per meter. Sodium adsorption ratio is 0 to 13. Reaction is moderately alkaline or strongly alkaline.
The Bw horizon has color of 2.5Y 6/2, 6/3or 6/4. Moist color is 2.5Y 4/2, 4/3 or 4/4. Texture is stratified fine sandy loam to silty clay loam. Clay content is 18 to 35 percent. Calcium carbonate equivalent is 1 to 5 percent. It is slightly effervescent to strongly effervescent. Gypsum content is 0 to 5 percent. Carbonates and gypsum content has been affected by irrigation. Electrical conductivity is 4.0 to 16.0 decisiemens per meter. Sodium adsorption ratio is 13 to 50.
The Bknz horizon has color of 2.5Y 6/2, 6/4, 6/6, 7/2 or 7/4. Moist color is 2.5Y 4/2, 4/4, 5/2, 5/3 or 5/4. Texture is stratified fine sandy loam to silty clay. Clay content is 18 to 50 percent. Calcium carbonate equivalent is 1 to 5 percent. It is slightly effervescent to violently effervescent with carbonates disseminated and/or segregated as threads, seams, or soft masses. Gypsum content is 0 to 5 percent. Carbonates and gypsum content has been affected by irrigation. Electrical conductivity is 4 to 30 decisiemens per meter. Sodium adsorption ratio is 13 to 50. Relict redoximorphic features may be present. Reaction is moderately alkaline to very strongly alkaline.
COMPETING SERIES: There are no competing series at this time.
GEOGRAPHIC SETTING: Posochanet soils are on fan skirts. Slope is 0 to 2 percent. These soils formed in alluvium derived dominantly from calcareous sedimentary rocks with influence from granitic rock sources in some areas. Elevation is 160 to 690 feet. The climate is arid and has hot dry summers and somewhat moist winters. The mean annual precipitation is 5 to 8 inches. The mean January temperature is 46 degrees F.; mean July temperature is 80 degrees F.; and the mean annual temperature is 62 to 65 degrees F. The frost-free period is 230 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Calflax, Cerini, Ciervo , Lethent, and Tranquillity soils. Calflax soils, on fan skirts, have a fine-loamy particle-size control section. Cerini soils, on alluvial fans, have a fine-loamy particle-size control section. Ciervo and Tranquillity soils, on fan skirts, have a fine particle-size control section. Lethent soils, on fan remnants, have a fine particle-size control section.
DRAINAGE AND PERMEABILITY: Moderately well drained; low or medium runoff; slow permeability. Some areas have developed a perched water table that occurs at a depth of 48 to 72 inches.
USE AND VEGETATION: These soils are used for irrigated crops, mainly cotton, wheat and seed alfalfa. Among other crops grown are safflower, barley and sugar beets. The natural vegetation was mainly annual grasses and forbs.
DISTRIBUTION AND EXTENT: San Joaquin Valley, California. The series is moderately extensive. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Fresno County, Western Part, California, 1999. Posochanet is the name of a former marsh located along the Arroyo Pasajero, about 5 miles east of the town of Coalinga, California.
REMARKS: This soil was mapped as Panoche series in the Coalinga Area, California Soil Survey, Series 1944, No.1 and in other areas in the south part of the San Joaquin Valley. Posochanet soil is stratified, with irregular decrease in organic carbon with depth and is exclusively saline-sodic, which differentiates it from the Panoche series. Posochanet soils also occur in lower landform positions (fan skirts) than Panoche soils, which were correlated to exclude saline-sodic soils. The Range in Characteristics for this series includes soils mapped in the Fresno County, Western Part and Tulare County, Western Part Soil Surveys. It does not currently completely cover the Posochanet soil mapped in the Kern County, Southwestern Part Soil Survey.
ADDITIONAL DATA: NSSL lab data is available for the Typical Pedon from soil sample number S87CA019-003 (4111-4116) This includes data for selenium content.