LOCATION LETHENT CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Natrargids
TYPICAL PEDON: Lethent clay loam - annual grasses and forbs on a slope of 1 percent at 224 feet elevation. (Colors are for dry soil unless otherwise stated. When described on 11/10/76 the soil was dry throughout.)
Ap--0 to 6 inches; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; strong coarse subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine and fine and few medium roots; many very fine interstitial and tubular pores; slightly effervescent, carbonates disseminated; moderately alkaline (pH 7.9); abrupt smooth boundary. (1 to 10 inches thick)
Btkny1--6 to 13 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; strong medium prismatic structure parting to strong medium subangular blocky; hard, friable, moderately sticky and very plastic; many very fine and fine and few medium roots; many very fine interstitial and many very fine and fine tubular pores; few thin clay films on faces of peds and in pores; common scattered gypsum crystals; strongly effervescent, carbonates disseminated and segregated as common fine irregular threads and soft masses; moderately alkaline (pH 8.2); abrupt smooth boundary. (7 to 19 inches thick)
Btkny2--13 to 24 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; very hard, friable, moderately sticky and very plastic; many very fine roots; many very fine interstitial and tubular pores; few thin clay films on faces of peds and in pores; common scattered gypsum crystals; strongly effervescent, carbonates disseminated and segregated as few fine irregular soft masses; moderately alkaline (pH 8.2); abrupt smooth boundary. (9 to 21 inches thick)
Btny--24 to 31 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak very coarse prismatic structure; hard, friable, moderately sticky and moderately plastic; many very fine roots; common very fine interstitial and tubular pores; few thin clay films on faces of peds and in pores; common scattered gypsum crystals; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 10 inches thick)
C1--31 to 52 inches; light yellowish brown (2.5Y 6/4) sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and few fine roots; many very fine interstitial and very fine and fine tubular pores; strongly alkaline (pH 8.5); abrupt wavy boundary. (21 to 24 inches thick)
C2--52 to 60 inches; light yellowish brown (2.5Y 6/4) sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common very fine roots; many very fine interstitial and common very fine tubular pores; strongly alkaline (pH 8.6).
TYPE LOCATION: Kings County, California; about 50 feet east of 25th Avenue; about 200 feet west and 1,700 feet south of the northwest corner of section 22, T. 19 S., R. 19 E., MDB&M; Latitude 36 degrees, 15 minutes, 57 seconds north and Longitude 119 degrees, 54 minutes, 13 seconds west; USGS Vanguard Topographic Quadrangle, NAD 27.
RANGE IN CHARACTERISTICS: The soil between the depths of 4 and 12 inches is dry more than 3/4 of the time (cumulative) and is not continuously moist for as long as 75 days. Mean annual soil temperature is 64 degrees to 68 degrees F. Electrical conductivity, sodium adsorption ratio and gypsum content are affected by agricultural practices and the depth to a high water table.
The A horizon has color of 5Y 5/2, 6/1; 2.5Y 4/2, 5/2, 5/4, 6/2, 6/4, 7/2; 10YR 4/3, 6/3, 6/2, 5/2, 5/3 or 4/3. Moist color is 5Y 3/2; 2.5Y 3/2, 4/2, 4/4, 5/2; 10YR 4/2 or 4/3. Organic matter content is less than 2 percent. Texture is fine sandy loam, silt loam or clay loam. Clay content is 8 to 35 percent. Calcium carbonate equivalent is 0 to 5 percent. It is usually slightly effervescent to strongly effervescent with disseminated carbonates, but is noneffervescent in some pedons. Electrical conductivity is 1 to 30 decisiemens per meter. Sodium adsorption ratio is 2 to 200. Reaction is moderately alkaline to very strongly alkaline.
The B horizon has color of 5Y 3/2, 5/2, 6/1, 6/2, 6/3; 2.5Y 5/2, 5/4, 6/2, 6/4, 7/2; 10YR 4/3, 6/3, 5/2 or 4/2. Moist color is 5Y 2/2, 3/2, 4/1, 4/2, 4/3; 2.5Y 3/2, 4/2, 4/4 or 10YR 4/2. Texture is clay loam, silty clay loam, clay, or silty clay. Clay content is 33 to 55 percent and averages 35 to 55 percent clay. Calcium carbonate equivalent is 0 to 5 percent. The Btkn horizon is slightly effervescent to violently effervescent. Carbonates are disseminated or segregated as threads and soft masses. The Btny horizon, that does not have carbonates, is not present in some pedons. Gypsum is not present in some pedons. Electrical conductivity is 1 to 30 percent. Sodium adsorption ratio is 13 to 200. Some pedons have redoximorphic features in the lower part of the Btkn horizon. Reaction is moderately alkaline to very strongly alkaline.
The C horizon has color of 5Y 6/2, 6/3, 6/4, 8/1, 8/2; 2.5Y 5/2, 5/4, 6/4, 7/4; 10YR 6/3, 6/4 or 5/2. Moist color of 5Y 4/3, 5/3, 6/3, 6/4, 7/2, 7/3; 2.5Y 4/2, 4/4 or 10YR 4/3. Texture is sandy loam, silt loam, loam, clay loam, or silty clay loam. Clay content is 10 to 40 percent. Calcium carbonate equivalent is 0 to 5 percent. Gypsum crystals are present in some pedons. Electrical conductivity is 1 to 40 decisiemens per meter. Sodium adsorption ratio is 13 to 200. Some pedons have redoximorphic features. Reaction is moderately alkaline to very strongly alkaline.
COMPETING SERIES: These are the Armpup and Oban series. Armpup soils (MLRA 30), on pediment remnants and ballena toe slopes, have a paralithic contact at a depth of 40 to 60 inches and have up to 70 percent coarse fragments in the Btkn horizon. Oban soils (MLRA 30), on valley troughs and basins, have gravel content as high as 25 percent in C horizons, have vesicular pores just below the upper plates in pedons with platy structure near the surface, have an E horizon in some pedons, occur at elevations of 2,300 to 2,500 feet and have mean annual precipitation of about 5 inches.
GEOGRAPHIC SETTING: Lethent soils occur on low lying alluvial fans, fan remnants, basins and basin rims. Slope is 0 to 2 percent. These soils formed in mixed alluvium dominantly from sedimentary and/or igneous rocks. Elevation is 190 to 1,000 feet. The climate is arid and has long, hot, dry summers and cool, somewhat moist winters. The mean annual precipitation is 5 to 8 inches. Mean January temperature is about 50 degrees F.; mean July temperature is about 83 degrees F.; mean annual temperature is 62 to 66 degrees F. The frost-free season is 220 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Calflax, Panoche and Nahrub soils. Calflax soils, on fan skirts, have a fine-loamy particle-size control section. Panoche soils, on alluvial fans, have a fine-loamy particle-size control section. Nahrub soils, on basin rims and basins, are somewhat porrly drained and do not have a Btkn natric horizon.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium or high runoff; very slow or slow permeability. Slow permeability is usually present in areas that have been highly modified by deep ripping, applications of soil amendments such as gypsum or sulfur, and applications of irrigation water that has reduced the salinity and sodicity.
USE AND VEGETATION: This soil is used for irrigated barley, sorghum, cotton, sugar beets, safflower, and pasture. The native vegetation is sparse stands of saltgrass, saltbush, and red brome.
DISTRIBUTION AND EXTENT: San Joaquin Valley, California. The series is of large extent. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Kings County, California, 1938.
REMARKS: This description represents a change in classification. Lethent soils were formerly classified as fine, montmorillonitic, thermic Xerollic Natrargids in 1977.
ADDITIONAL DATA: NSSL characterization data sample number S87CA-019-006 (4130-4135) type location for a taxonomic unit. Other characterization data sample numbers include S87CA-019-001 (4099-4104), S87CA-019-004 (4117-4122) and S87CA-109-005 (4123-4129) which are all taxadjuncts that have been ripped and modified for agricultural uses.