LOCATION POLVADERO CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Typic Natrargids
TYPICAL PEDON: Polvadero sandy loam - on a convex northwest facing slope of 2 percent in a cultivated field of barley at 620 feet elevation. (Colors are for dry soil unless otherwise stated. When described November 10, 1982, the soil was moist from 0 to 4 inches and dry below.)
Ap--0 to 7 inches; light yellowish brown (10YR 6/4) sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure parting to weak fine subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; few very fine tubular and many very fine interstitial pores; strongly effervescent, carbonates disseminated, calcium carbonate equivalent is 5 percent; electrical conductivity is 0.4 decisiemens per meter; sodium adsorption ratio is 0; 4 percent subangular fine and medium gravel and 1 percent subangular cobbles; moderately alkaline (pH 8.4); abrupt smooth boundary. (6 to 9 inches thick)
A--7 to 12 inches; light yellowish brown (10YR 6/4) sandy loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine tubular and many very fine interstitial pores; violently effervescent, carbonates disseminated, calcium carbonate equivalent is 7 percent; electrical conductivity is 0.4 decisiemens per meter; sodium adsorption ratio is 3; 4 percent subangular fine and medium gravel; moderately alkaline (pH 8.4); abrupt wavy boundary. (2 to 15 inches thick)
Btkn1--12 to 30 inches; light yellowish brown (10YR 6/4) sandy clay loam, yellowish brown (10YR 5/4) moist moderate medium prismatic structure parting to moderate medium subangular blocky; hard, very friable, slightly sticky and plastic; few very fine roots; many very fine tubular and interstitial pores; few moderately thick clay films on faces of peds and in pores and few thin clay films in bridges; violently effervescent, carbonates disseminated and segregated as many fine and medium irregularly shaped threads, seams, soft masses, and concretions, calcium carbonate equivalent is 28 percent; electrical conductivity is 1.0 decisiemens per meter; sodium adsorption ratio is 16; 3 percent subangular fine and medium gravel; strongly alkaline (pH 8.8); clear wavy boundary. (8 to 21 inches thick)
Btkn2--30 to 52 inches; light yellowish brown (10YR 6/4) sandy clay loam, yellowish brown (10YR 5/4) moist; moderate medium angular blocky structure; hard, friable, slightly sticky and plastic; common very fine tubular and many very fine interstitial pores; very few moderately thick clay films on faces of peds and in pores and very few thin clay films in bridges; violently effervescent, carbonates disseminated and segregated as many common irregularly shaped threads, seams, soft masses, and concretions, calcium carbonate equivalent is 10 percent; electrical conductivity is 1.5 decisiemens per meter; sodium adsorption ratio is 15; 2 percent subangular fine and medium gravel; strongly alkaline (pH 9.0); abrupt smooth boundary. (8 to 25 inches thick)
C--52 to 60 inches; light yellowish brown (10YR 6/4) sandy loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common very fine tubular and many very fine interstitial pores; very slightly effervescent, carbonates disseminated and segregated in few fine rounded soft masses, calcium carbonate equivalent is 3 percent; electrical conductivity is 1.8 decisiemens per meter; sodium adsorption ratio is 23; 2 percent subangular fine and medium gravel; strongly alkaline (pH 8.5).
TYPE LOCATION: Fresno County, California; approximately 8 miles east of the community of Coalinga, 2.75 miles west of Interstate 5 and 2 miles south of Jayne Avenue; 290 feet east and 135 feet south of the northwest corner of section 18, T. 21 S., R. 17 E., MDB&M; Latitude 36 degrees, 06 minutes, 03 seconds north and Longitude 120 degrees, 10 minutes, 50 seconds west; USGS Avenal Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: Unless irrigated, the soil between the depths of 8 to 16 inches is dry in all parts from April 1 until January 1 and is moist in some or all parts for only 60 to 90 consecutive days from January through March. The soil temperature is always above 47 degrees F. The mean annual soil temperature is 64 to 70 degrees F. Organic matter content is less than 1 percent, unless highly modified by feedlot manure. Gravel content is 0 to 15 percent. Cobble content is 0 to 1 percent.
The A horizon has color of 10YR 5/3, 5/4, 6/2, 6/3, 6/4 or 2.5Y 6/2. Moist color is 10YR 4/2, 4/3, 5/3 or 2.5Y 4/2. Texture is sandy loam or fine sandy loam. Clay content is 6 to 18 percent. Calcium carbonate equivalent is 0 to 7 percent. It is noneffervescent to violently effervescent. Electrical conductivity is 0 to 2 decisiemens per meter. Sodium adsorption ratio is 0 to 8. Reaction is slightly alkaline or moderately alkaline.
The Btkn horizon has color of 10YR 5/4, 5/6, 6/3, 6/4, 7/2, 7/3, 7/4; 2.5Y 6/2 or 6/4. Moist color is 10YR 3/3, 4/2, 4/3, 4/4, 5/4; 2.5Y 4/2, 4/4 or 5/4. Texture is sandy loam, loam or sandy clay loam. Clay content is 18 to 30 percent. Calcium carbonate equivalent is 15 to 30 percent in the upper part that is a calcic horizon and 5 to 15 percent in the lower part. It is strongly effervescent or violently effervescent. Electrical conductivity is 1 to 2 decisiemens per meter. Sodium adsorption ratio is 13 to 50 in this natric horizon. Reaction is moderately alkaline or strongly alkaline.
The C horizon has color of 10YR 5/4, 6/2, 6/3, 6/4, 7/3; 2.5Y 6/2 or 6/4. Moist color is 10YR 4/2, 4/3, 5/3, 5/4 or 2.5Y 4/2. Texture is sandy loam, loam or sandy clay loam. Clay content is 18 to 30 percent. Calcium carbonate equivalent is 1 to 10 percent. It is very slightly effervescent to violently effervescent. Electrical conductivity is 1 to 2 decisiemens per meter. Sodium adsorption ratio is 8 to 50. Reaction is moderately alkaline or strongly alkaline. Lithologic discontinuities and buried A and B horizons occur in some pedons.
COMPETING SERIES: These are the Casaga, Garces, Leuhman, Norob and Tipnat (T) series. Casaga soils (MLRA 30), on erosional fan remnants, have mean annual precipitation of 4 to 6 inches, with some precipitation during summer and have 35 to 60 percent rock fragments in 2Bk and 2By horizons. Garces soils (MLRA 17), on fan remnants, formed in granitic alluvium and do not have a calcic horizon. Leuhman soils (MLRA 30), on alluvial flats in lacustrine sediments with influence from eolian materials, are moderately well drained and do not have a calcic horizon. Norob soils (MLRA 30), on alluvial plains and alluvial flats in the Mojave Desert, are moderately well drained and do not have a calcic horizon. Tipnat soils (MLRA 30), on alluvial flats in mixed alluvium from volcanic sources, do not have a calcic horizon.
GEOGRAPHIC SETTING: Polvadero soils are on fan remnants. Slope is 0 to 15 percent. These soils formed in alluvium derived dominantly from calcareous sedimentary rock. Elevation is 250 to 1,000 feet. The climate is arid with hot dry summers and cool, somewhat moist winters. Mean annual precipitation is 6 to 8 inches. Mean January temperature is 45 degrees F.; mean July temperature is 84 degrees F.; mean annual temperature is 62 to 65 degrees F. Frost-free season is 250 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cerini, Guijarral, Panoche and Kettleman soils. Cerini and Panoche soils, on alluvial fans, do not have a natric horizon or a calcic horizon. Guijarral soils, on fan remnants, have a cambic horizon and do not have a natric horizon or a calcic horizon. Kettleman soils, on hills, are moderately deep, have a cambic horizon and do not have a natric horizon or a calcic horizon.
DRAINAGE AND PERMEABILITY: Well drained; low to high runoff (Polvadero soils under feedlots have very high runoff); moderately slow permeability (Polvadero soils under feedlots have very slow permeability).
USE AND VEGETATION: These soils are used for livestock grazing, feedlots, wildlife habitat, oil fields and as cropland growing irrigated crops. The vegetation in nonirrigated areas is mainly red brome, rattail fescue, filaree and saltbush (Atriplex). The main irrigated crops are almonds, pistachios, barley, cotton and wheat.
DISTRIBUTION AND EXTENT: The western edge of the San Joaquin Valley. The soils are of moderate extent. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Fresno County, California, 2002. Named after Polvadero Gap in Fresno County.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon - the zone from the surface of the soil to a depth of 12 inches (Ap, A horizons)
2. Natric horizon - the zone from 12 inches to a depth of 52 inches (Btkn horizon)
3. Calcic horizon - the zone from 12 inches to a depth of 30 inches (Btkn1 horizon)
ADDITIONAL DATA: The Ap and Btkn1 horizons in the typical pedon, sample numbers S82CA019-001 (837802) and S82CA019-002 (837803) have some data determined by the National Soil Survey Laboratory, Lincoln, Nebraska. According to notes from the NSSL, these samples did not disperse well in their particle size analysis. That is an unexpected result for a soil with a natric horizon. Some cementation may have been inherited from the parent material or may result from carbonates. This data is not currently available through the NSSC website.