LOCATION GEPFORD CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Natraquerts
TYPICAL PEDON: Gepford clay on a slope of less than 1 percent under a cotton crop at 210 feet elevation. (Colors are for dry soil unless otherwise noted. When described on 11/2/78 cotton was mature and the soil was moist to 40 inches and wet below this point, water table was at 44 inches.)
Ap1--0 to 12 inches; gray (5Y 5/1) clay, very dark gray (5Y 3/1) moist; strong very coarse prismatic structure parting to strong medium and coarse angular blocky; hard, very firm, moderately sticky and moderately plastic; many very fine and few fine roots; common very fine tubular and many very fine interstitial pores; strongly effervescent, carbonates disseminated and segregated as few fine irregularly shaped soft masses; few fine distinct pale olive (5Y 6/3) and dark yellowish brown (10YR 4/4) masses of redoximorphic iron accumulation, olive (5Y 5/3) and dark yellowish brown (10YR 4/4) moist; slightly alkaline (pH 7.8); abrupt smooth boundary. (6 to 13 inches thick)
Ap2--12 to 25 inches; variegated gray (5Y 5/1), dark gray (5Y 4/1) and gray (N 5/0) clay, dark olive gray (5Y 3/2), dark gray (5Y 4/1) and black (5Y 2.5/1) moist; moderate very coarse prismatic structure; cracks 1.5 inches wide to a depth of 19 inches; hard, firm, moderately sticky and very plastic; many very fine and common fine roots; common very fine tubular and many very fine interstitial pores; strongly effervescent, carbonates disseminated and segregated as few fine irregularly shaped soft masses; common medium distinct greenish gray (5G 6/1) redoximorphic iron depletions, greenish gray (5G 5/1) moist and few fine distinct light olive brown (2.5Y 5/4) moist masses of iron accumulation; moderately alkaline (pH 8.0); abrupt smooth boundary. (10 to 16 inches thick)
Bkg1--25 to 30 inches; olive (5Y 5/3) clay, olive (5Y 4/3) moist; massive; hard, firm, very sticky and very plastic; many very fine tubular pores; slightly effervescent, carbonates disseminated and segregated as few fine irregularly shaped soft masses; common pressure faces and wedge-shaped aggregates which are tilted at a 30 degree angle; many fine distinct very dark gray (5Y 3/1) manganese concretions, black (5Y 2.5/1) moist and many fine faint olive (5Y 5/4) masses of iron accumulation, dark yellowish brown (10YR 3/4) moist; moderately alkaline (pH 8.2); abrupt smooth boundary. (4 to 12 inches thick)
Bkg2--30 to 38 inches; gray (5Y 6/1) clay, dark gray (5Y 4/1) moist; massive; very hard, firm, moderately sticky and very plastic; many very fine tubular pores; slightly effervescent, carbonates disseminated and segregated as few fine irregularly shaped soft masses and common medium very hard nodules; common pressure faces and wedge-shaped aggregates which are tilted at a 30 degree angle; many fine distinct pale olive (5Y 6/3) masses of redoximorphic iron accumulation, olive (5Y 4/3) moist; moderately alkaline (pH 8.3); abrupt smooth boundary. (5 to 20 inches thick)
2Bkg3--38 to 54 inches; light olive gray (5Y 6/2) clay loam, gray (5Y 5/1) moist; massive; very hard, firm, moderately sticky and moderately plastic; many very fine interstitial pores; slightly effervescent, carbonates disseminated and segregated as common medium very hard nodules; common pressure faces; many fine distinct and prominent light yellowish brown (2.5Y 6/4) and few fine distinct brown (7.5YR 5/4) and grayish brown (10YR 5/2) masses of redoximorphic iron accumulation, light olive brown (2.5Y 5/4), brown (7.5YR 4/4) and very dark grayish brown (10YR 3/2) moist; moderately alkaline (pH 8.3); abrupt smooth boundary. (4 to 20 inches thick)
2Bkg4--54 to 60 inches; pale yellow (5Y 7/3) clay loam, olive (5Y 5/3) moist; massive; very hard, friable, moderately sticky and moderately plastic; many very fine interstitial pores; slightly effervescent, carbonates disseminated and segregated as common medium very hard nodules; few fine distinct gray (5Y 6/1) iron depletions, gray (5Y 5/1) moist, and pale yellow (2.5Y 7/4) masses of redoximorphic iron accumulation that are light olive brown (2.5Y 5/4) moist; moderately alkaline (pH 8.2).
TYPE LOCATION: Kings County, California; about 800 feet west of the North Fork Kings River and 60 feet north of Grangeville Blvd.; 2300 feet east and 60 feet north of the southwest corner of section 22, T. 18 S., R. 19 E., MDB&M; Latitude 36 degrees, 20 minutes, 38 seconds north and Longitude 119 degrees, 53 minutes, 47 seconds west; USGS Vanguard Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 63 to 68 degrees F. The moisture control section is moist in some part all of the time and is saturated for up to 4 months, unless drained. Average clay in the 10 to 40 inch control section is 50 to 60 percent. Organic matter is 1 to 3 percent in the surface horizons and decreases irregularly with increasing depth. Calcium carbonate equivalent is 1 to 5 percent in the surface horizon and 2 to 15 percent in the lower horizons. Carbonate is disseminated and/or segregated as concretions, threads, nodules and soft masses. Conductivity of the saturation extract ranges from 2 to 16 decisiemens per meter. Sodium adsorption ratio is 2 to 30 in the surface layer and 8 to 50 in the subsoil, and some part of the subsoil always is greater than 13. Reaction of the soil profile is slightly alkaline to strongly alkaline, typically increasing in alkalinity with increasing depth.
The A horizon has color of 5Y 4/1, 4/2, 5/1, 5/2 or 6/2. Moist color is 5Y 2/1, 2.5/1, 3/1, 3/2, 4/2, 4/1, or N 5/0. Texture is clay or silty clay. Cracks, when dry, range from 1/4 to 1 inch wide and extend up to 29 inches deep in the soil. Redoximorphic features may be present in some A horizons.
The B horizon has color of 2.5Y 6/2, 6/4; 5Y 4/1, 5/1, 5/2, 5/3, 6/1, 6/2, 7/1, 7/2, 7/3 or 8/1. Moist color is 2.5Y 4/4, 5/4; 5GY 4/1, 5/1; 5Y 3/1, 3/2, 4/1, 4/2, 4/3, 5/1, 5/2 or 5/3. Moist colors of redoximorphic features are 7.5YR 4/4; 10YR 3/2, 3/4, 3/6, 4/4, 4/6; 2.5Y 4/4, 5/4; 5Y 2/1, 2.5/1, 4/1, 4/3, 4/4, 5/1, 5/2 5/3, 6/2, 6/3, 6/4; 5GY 4/1, 4/2, 5/1; 5G 5/1; N 2/0, 5/0; 5YR 3/2 or 3/3. Texture is clay loam, clay or silty clay in the upper part and may have thin strata of sand to clay in the lower part. Hard carbonate nodules are few or common. Few to common pressure faces are in the B horizons. Wedge-shaped aggregates that are tilted at least 10 degrees occur in all pedons. Some pedons have Bkyg horizons. Gypsum content is variable due to additions of gypsum as a soil amendment.
COMPETING SERIES: There are no competing series at this time.
GEOGRAPHIC SETTING: Gepford soils are on flood plains, basin floors and basin rims. The soils formed in mixed alluvium derived dominantly from granitic rocks, and influenced by lacustrine sediments. Slope is0 to 1 percent. Elevations are 120 to 250 feet. Climate is arid to semiarid and has hot dry summers and cool moist winters. Mean annual precipitation varies from 6 to 8 inches. Mean January temperature is 45 degrees F.; mean July temperature is 82 degrees F.; mean annual temperature is 62 to 66 degrees F. Frost-free season varies from 220 to 275 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lethent, Pitco, Tachi and Vanguard series. Lethent soils on fan remnants have a natric horizon and an ochric epipedon. Pitco soils on basin rims and flood plains lack carbonates in any part of the profile. Tachi soils on basin floors and flood plains have a very-fine particle-size control section. Vanguard soils on flood plains have a coarse-loamy particle-size control section.
DRAINAGE AND PERMEABILITY: Poorly drained; ponded in some areas; runoff is medium or high; very slow permeability. Sandy substratum phases occur with moderately rapid or rapid permeability in the substratum. The perched water table has been lowered to 30 to 72 inches because runoff water has been intercepted. Unless protected, the soil is flooded for 30 to 90 days from January through March once every 3 years. Many areas that are protected by upstream diversions of water (such as dams, levees and canals) are rarely flooded.
USE AND VEGETATION: Used primarily for irrigated cropland to produce barley, cotton, safflower, grain, sorghum, and sugar beets. It is also used for dairy and cattle production and building site development.
DISTRIBUTION AND EXTENT: San Joaquin Valley, California. The series is of moderate extent. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Kings County, California, 1980.
REMARKS: Reaction is highly variable as a result of addition of gypsum and sulfur by farmers. Where farmers have added significant amounts of gypsum or sulfur the soil reaction will be lowered. These horizons with segregated gypsum are designated with the "y" horizon suffix.
The Gepford series was initially classified as Vertic Haplaquolls. This was changed to Typic Natraquerts when wedge-shaped aggregates weredescribed in the Gepford profiles.
The original competing series before taxonomy change were the Dospalos, Portageville (T), and Tulare series. Dospalos soils have 35 to 50 percent clay in the particle-size control section and have a conductivity of less than 2 decisiemens per meter. Portageville soils lack salinity. Tulare soils have a horizon with more than 15 percent calcium carbonate and lack carbonate nodules in the B horizon. They also lack redoximorphic features in the A horizons.
Diagnostic Features and Characteristics:
1.0 Mollic Epipedon--The zone from the soil surface to a depth of about 25 inches (Ap horizons). These layers are not designated with a "g" horizon subscript because it has been ripped and tilled.
2.0 Fine Particle Size Family--The zone from a depth of 10 inches to a depth of about 40 inches has an average of 50 to 60 percent clay.