LOCATION CIERVO CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Haplocambids
TYPICAL PEDON: Ciervo clay, saline-sodic - on a slope of less than 1 percent in a cultivated unplanted field at an elevation of 247 feet. (Colors are for dry soil unless otherwise stated. When described on September 18, 1985, the soil was dry from 0 to 17 inches and moist below.)
Ap1--0 to 7 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate medium and coarse subangular blocky structure; hard, firm, very sticky, and very plastic; few very fine, fine and medium roots; common very fine tubular pores; strongly effervescent, carbonates disseminated, calcium carbonate equivalent is 3 percent; electrical conductivity is 1.2 decisiemens per meter; sodium adsorption ratio is 3; moderately alkaline (pH 8.1); abrupt smooth boundary. (3 to 10 inches thick)
Ap2--7 to 17 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate coarse subangular blocky structure; very hard, firm, moderately sticky, and moderately plastic; few very fine and fine roots; common very fine tubular pores; strongly effervescent, carbonates disseminated, calcium carbonate equivalent is 3 percent; electrical conductivity is 1.2 decisiemens per meter; sodium adsorption ratio is 6; moderately alkaline (pH 8.3); abrupt smooth boundary. (5 to 15 inches thick)
Bw--17 to 27 inches; light gray (2.5Y 7/2) clay, light olive brown (2.5Y 5/4) moist; weak medium subangular blocky structure; extremely hard, firm, moderately sticky, and moderately plastic; few very fine and fine roots; common very fine tubular pores; strongly effervescent, carbonates disseminated and segregated as few fine irregularly shaped threads, calcium carbonate equivalent is 4 percent; electrical conductivity is 1.5 decisiemens per meter; sodium adsorption ratio is 12; strongly alkaline (pH 8.6); abrupt smooth boundary. (6 to 15 inches thick)
Bknyz--27 to 41 inches; light gray (2.5Y 7/2) silty clay, light olive brown (2.5Y 5/4) and dark grayish brown (2.5Y 4/2) moist; weak medium platy structure; hard, very friable, moderately sticky, and moderately plastic; few very fine and fine roots; many very fine tubular pores; strongly effervescent, carbonates disseminated and segregated as few fine irregularly shaped threads, calcium carbonate equivalent is 3 percent; common fine irregularly shaped soft masses of gypsum crystals, calcium sulfate content is 5 percent; electrical conductivity is 9.5 decisiemens per meter; sodium adsorption ratio is 21; moderately alkaline (pH 8.0); abrupt smooth boundary. (10 to 22 inches thick)
Bknz--41 to 60 inches; light gray (2.5Y 7/2) clay loam, light olive brown (2.5Y 5/4) moist; massive; hard, very friable, slightly sticky, and moderately plastic; few very fine roots; common very fine tubular pores; strongly effervescent, carbonates disseminated and segregated as few fine irregularly shaped threads, calcium carbonate equivalent is 3 percent; electrical conductivity is 12.4 decisiemens per meter; sodium adsorption ratio is 29; moderately alkaline (pH 8.2).
TYPE LOCATION: Fresno County, California; approximately 3.1 miles east of the California Aqueduct, and 8 miles southwest of the community of Mendota; about 1,300 feet north and 2,400 feet east of the southwest corner of section 9, T.15S., R.14E., MDBM; Latitude 36 degrees, 38 minutes, 12 seconds north and Longitude 120 degrees, 27 minutes, 04 seconds west; USGS Tranquillity Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: Unless irrigated, the soil between the depths of 4 and 12 inches is dry in all parts from April 1 to December 1 and is moist in some or all parts for only 70 to 90 consecutive days from December through March. The soil temperature is always above 47 degrees F. The mean annual soil temperature is 63 to 65 degrees F. Organic matter content is less than 1 percent and decreases regularly with depth. Clay content is 20 to 55 percent but the 10 to 40 inch control section averages 35 to 50 percent clay. Clay content usually decreases with depth. Carbonates are commonly disseminated in the A horizon and segregated below as soft masses or threads. Calcium carbonate equivalent is 1 to 5 percent. Gypsum content is 0 to 5 percent. Gypsum content is variable due to additions of gypsum as a soil amendment. Gypsum crystals are present in some part of most pedons. Salinity is 0 to 16 decisiemens per meter. Sodium adsorption ratio is 1 to 50. Some areas are nonsaline-nonsodic. Reaction is moderately alkaline or strongly alkaline. Nonsaline-nonsodic phases are moderately alkaline.
The A horizon has color of 2.5Y 5/2, 6/2, 6/4 or 7/2. Moist color is 2.5Y 4/2, 4/3, 4/4 or 5/4. Texture is clay loam or clay. Linear extensibility percent is 6 to 9.
The Bw horizon has color of 2.5Y 5/2, 5/4, 6/2, 6/4, 7/2 or 7/4. Moist color is 2.5Y 4/2, 4/4, 5/2 or 5/4. Texture is clay loam, clay or silty clay. Linear extensibility percent is 6 to 9.
The Bknyz and Bknz horizons have color of 2.5Y 5/2, 5/4, 6/2, 6/4, 7/2 or 7/4. Moist color is 2.5Y 4/2, 4/4, 5/2, or 5/4. Texture is loam, clay loam, or silty clay loam. Some pedons do not have a Bknyz horizon. Linear extensibility percent is 6 to 9 in the Bknyz horizon and 3 to 6 in the Bknz horizon.
COMPETING SERIES: This is the Caticon series. Caticon soils (MLRA 42) are well drained soils that have 7.5YR hues, on lake plains on basin floors. Most precipitation falls during the months of July through September.
GEOGRAPHIC SETTING: Ciervo soils are on fan skirts. Slope is 0 to 2 percent. The soils formed in alluvium derived dominantly from sedimentary rock. Elevation is 170 to 735 feet. The climate is arid with hot, dry summers and cool, moist winters. Many days in winter have ground fog. Mean annual precipitation is 6 to 8 inches. Mean January temperature is about 45 degrees F; mean July temperature is about 82 degrees F; mean annual temperature is about 62 to 64 degrees F. Frost-free season is 240 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Tranquillity, Posochanet, Calflax and Panoche soils. Tranquillity soils have intersecting slickensides. Posochanet soils have a fine-silty particle-size control section. Calflax and Panoche soils have a fine-loamy particle-size control section. Tranquillity, Posochanet and Calflax soils are on fan skirts. Panoche soils are on alluvial fans.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium or high runoff; very slow permeability. Nonsaline-nonsodic phases have slow permeability.
USE AND VEGETATION: Used mainly for irrigated cropland to produce crops such as cotton, alfalfa, sugar beets, wheat, onions and tomatoes. Native vegetation is annual grasses, forbs and saltbush (Atriplex spp.).
DISTRIBUTION AND EXTENT: Southern part of the San Joaquin Valley in California. The soils are of large extent. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Fresno County, California, l985. Ciervo soils are named after a mountain peak in the area.
REMARKS: Previously mapped as Oxalis and Panoche series in the Soil Survey of the Mendota Area, California, Series 1940, No. 18 and in the Soil Survey of the Coalinga Area, California, Series 1944, No 1.
Clay texture is the dominant surface texture of this soil and texture which was determined in the field, therefore clay texture was described in the Ap1 horizon. The laboratory data showed 39.3 percent clay. This soil occurs in an area which is subject to dramatic changes in soil salinity and sodicity due to position on the landscape (fan skirts) and the prevalence of perched water tables near the surface.
Major Diagnostic Horizons:
The Ciervo series was initially classified as Vertic Torriorthents. This was changed to Vertic Haplocambids when a cambic horizon was described in the Ciervo profiles. The presence of a cambic horizon is based on the following characteristics:
1. Soil structure in the cambic horizon (unless moist from irrigation or rainfall or drastically modified by deep ripping).
2. Removal of carbonates or gypsum from the cambic horizon.
3. Accumulation of carbonates or gypsum below the cambic horizon which supports loss of carbonate or gypsum from overlying horizons.
4. Higher chroma in the cambic horizon in some pedons.
5. Most areas of Ciervo soil are irrigated with 2 to 3 feet of water per year applied for crop production. Previous to irrigation, only about 7 inches of precipitation, coupled with flood water, was available for soil development. Movement of carbonates, gypsum, fertilizers, and salt through the soil profile has created more pronounced cambic horizons because of application of irrigation water.
1. Ochric Epipedon--0 to 17 inches (Ap1, Ap2).
1.1 Cambic Horizon -- 17 to 27 inches (Bw).
1.2 Removal of carbonates or gypsum from the cambic horizon. Pedons which have a horizon with 5 percent gypsum qualify for a gypsic horizon. They are not classified as gypsic horizons however, because 5 percent gypsum is the minimum requirement for a gypsic horizon and 5 percent gypsum is the maximum gypsum found in the Ciervo series. In all instances where gypsum content is as high as 5 percent, there have been significant amounts of gypsum that have been added as a soil amendment.
1.3 Zone of redistribution -- 27 to 60 inches (Bknyz, Bknz).
Other Diagnostic Features and Characteristics:
1. Fine Family
1.1 NSSL results show 34 to 47 percent clay in the typical pedon. There is an average 45 percent clay from 10 to 40 inches.
2. Smectitic Mineralogy
2.1 X-ray diffraction studies show smectite is the dominant clay mineral in this soil.
3. Thermic Temperature Regime
3.1 Soil temperature regime is assumed to be thermic based upon data from Mendota Dam and Panoche Junction. MAAT is 62 to 64 degrees F.
4. Vertic Subgroup
4.1 Linear extensibility percent is 8for the typical pedon to a depth of 104 cm.
4.2 Since this soil is cultivated and irrigated, cracks are difficult to observe. If unirrigated, cracks are assumed to be at least 5 mm wide at a depth of 50 cm, at least 30 cm long in some part, and extend upward to the soil surface or the base of an Ap horizon.
5. Torric Moisture Regime
5.1 Unless irrigated, the 4 to 12 inch SMCS is assumed to be dry in all parts from April 1 to December 1 and is moist in some or all parts for only 70 to 90 consecutive days. Based upon data from Mendota Dam (MAP 7.7 inches) and Panoche Junction (MAP 6.0 inches) climate stations.
5.2 The soil temperature exceeds 47 degrees F. from January to December (365 days).
ADDITIONAL DATA: NSSL characterization data pedon sample number S85CA019-005 (5375-5379) for the typical pedon. Other pedons with NSSL data are S85CA019-004 (5369-5374) and S86CA019-012 (3158-3162).