LOCATION SAN JOAQUIN CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Abruptic Durixeralfs
TYPICAL PEDON: San Joaquin loam - on east facing complex slope of 1 percent in a vineyard at elevation of 40 feet. (Colors are for dry soil unless otherwise stated. When described on May 3, 1983, the soil was moist throughout).
Ap--0 to 6 inches; brown (7.5YR 5/4) loam, dark brown (7.5YR 3/4) moist; moderate medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial and few fine tubular pores; few fine very dark gray (10YR 3/1) Fe-Mn concretions and stains; neutral (pH 7.3); clear wavy boundary. (5 to 15 inches thick)
Bt1--6 to 10 inches; brown (7.5YR 5/4) loam, reddish brown (5YR 4/4) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular and common very fine interstitial pores; few thin clay films on ped faces and bridging mineral grains; few fine very dark gray (10YR 3/1) Fe-Mn concretions and stains; moderately acid (pH 5.7); clear wavy boundary. (0 to 8 inches thick)
Bt2--10 to 16 inches; brown (7.5YR 5/4) loam, reddish brown (5YR 4/4) moist; moderate medium subangular blocky structure; very hard, friable, sticky and plastic; many very fine and few fine tubular and common very fine interstitial pores; few thin clay films on ped faces, common thin clay film bridging mineral grains; common light gray (10YR 7/2) fine sand or silt grains on ped faces and lining pores; few fine very dark gray (10YR 3/1) Fe-Mn concretions; moderately acid (pH 5.9); abrupt wavy boundary. (0 to 12 inches thick)
2Bt3--16 to 21 inches; brown (7.5YR 5/4) clay; strong brown (7.5YR 4/6) moist; moderate medium prismatic structure; extremely hard, firm, sticky and very plastic; few very fine, fine and medium roots; common very fine tubular and few very fine interstitial pores; common moderately thick clay films on ped faces, many thin clay films bridging mineral grains; common slickensides that do not intersect; about 3 percent fine very dark gray diameter Fe-Mn concretions; neutral (pH 7.0); gradual wavy boundary. (4 to 10 inches thick)
2Bt4--21 to 26 inches; brown (7.5YR 5/4) clay, dark brown (7.5YR 4/4) moist; moderate medium prismatic structure; extremely hard, firm, sticky and plastic; few very fine, fine and medium roots; common very fine tubular and few very fine interstitial pores; common moderately thick clay films on ped faces and common thin clay films as bridges between mineral grains; about 3 percent very dark gray (10YR 3/1) Fe-Mn concretions and stains; neutral (pH 7.3); abrupt wavy boundary. (3 to 5 inches thick)
2Bqm1--26 to 29 inches; variegated brown (7.5YR 5/4) and light brown (7.5YR 6/4) indurated duripan, brown (7.5YR 4/4) moist; extremely hard and brittle; silica and sesquioxide cementation in more than 90 percent of the matrix; few fine Fe-Mn concretions; strongly effervescent with secondary lime in fractures; common very fine close tubular pores; moderately alkaline (pH 8.0); gradual smooth boundary. (1 to 10 inches thick)
2Bqm2--29 to 48 inches; variegated brown (7.5YR 5/4) and strong brown (7.5YR 4/6) duripan, dark brown (7.5YR 3/4) moist; extremely hard and brittle; silica and sesquioxide cementation in more than 90 percent of the matrix; common fine Fe-Mn concretions and stains; strongly effervescent with segregated lime in fractures; common very fine closed tubular pores; moderately alkaline (pH 8.0); clear wavy boundary. (1 to 25 inches thick)
2Bq--48 to 60 inches; brown (7.5YR 5/4) duripan, dark brown (7.5YR 3/4) moist; extremely hard and brittle; silica and sesquioxide cementation in 70 to 90 percent of matrix; common fine Fe-Mn concretions; many very fine interstitial pores; moderately alkaline (pH 8.0).
TYPE LOCATION: San Joaquin County, California; about 5 miles northeast of Lodi, 3,700 feet west of intersection of Southern Pacific Railroad and Forest Lake Road; 1,100 feet south of Forest Lake Road and about 100 feet west into vineyard; 1,700 feet north and 2,600 feet east of the southwest corner of sec. 3, T. 4 N., R. 6 E., MDB&M.; Lodi North quadrangle.
RANGE IN CHARACTERISTICS: Depth to the duripan ranges from 20 to 40 inches. The mean annual soil temperature varies from 60 degrees to 64 degrees F and the soil temperature is not below 47 degrees F at any time. The soil, at depths of about 7 to 24 inches or directly above the duripan, is dry in all parts from June to November and is moist in some or all parts the rest of the year. Clay increases by more than 15 percent absolute.
The Ap or A horizon has colors of 7.5YR 4/4, 5/2, 5/4, 5/6, 6/2, 6/4, 6/6, 7/6, 7/8; 5YR 4/3, 4/4, 4/6, 5/3, 5/4, 5/6, 5/8; 10YR 4/3, 5/3, 5/4, 6/3 or 6/4. Moist colors are 1 or 2 units darker in value. It is sandy loam, silt loam, fine sandy loam or loam. Reaction is moderately acid or slightly acid, but may be neutral where liming has taken place. Base saturation is greater than 75 percent.
The Bt horizon when present has colors of 7.5YR 5/4, 5/6, 6/6 and 5YR 5/6. Moist colors are 7.5YR 4/4; 5YR 4/4. Textures are sandy clay loam, loam or silt loam. It is moderately acid to neutral.
The 2Bt horizon has colors of 7.5YR 6/6, 6/4, 5/6, 5/4, 5/2, 4/6, 4/4; 5YR 5/8, 5/6, 4/6, 5/4, 4/4, 3/4, 4/3, 3/3; 2.5YR 5/4, 4/8, 4/6, 4/4 or 3/4. Moist colors are 1 or 2 units of value darker. It is clay loam or clay but average clay content is 35 to 50 percent. It is slightly acid to slightly alkaline.
There is an abrupt boundary at or within the upper part of the argillic horizon with an absolute clay increase of at least 15 percent.
The duripan has colors of 10YR 7/3, 6/4, 5/6, 5/4; 7.5YR 7/2, 6/4, 5/6, 5/4, 5/2, 4/6, 4/4, 4/2; 5YR 3/3, 4/3, 4/4, 5/6 or 5/8 and is usually variegated. It is cemented with iron and or silica becoming less indurated with depth. Segregated carbonates do not line fractures in some pedons.
COMPETING SERIES: These are the Yuvas and Redding series. Redding soils have base saturation of 35 to 75 percent in the A and Bt horizon and are gravelly or cobbly in the control section. Yuvas soils have a paralithic contact at 21 to 40 inches.
GEOGRAPHIC SETTING: San Joaquin soils are on hummocky, nearly level to undulating terraces at elevations of about 20 to 500 feet. Some areas have been leveled. Slopes range from 0 to 9 percent. They formed in alluvium from mixed but mainly granitic rock sources. The climate is dry with hot dry summers and cool moist and foggy winters. Mean annual precipitation varies from 10 to 22 inches. Average January temperature is 45 degrees F; average July temperature is 80 degrees F; mean annual temperature is 60 to 63 degrees F. Frost-free period is 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Exeter, Fiddyment, Madera, Alamo and Cometa soils. Alamo soils are clayey throughout. Cometa soils lack a duripan. Exeter soils lack an abrupt boundary with at least 15 percent clay increase within the argillic horizon. Fiddyment soils average less than 35 percent within the control section. Madera soils have montmorillonitic mineralogy.
DRAINAGE AND PERMEABILITY: Well and moderately well drained; medium to very high runoff; very slow permeability. Some areas are subject to rare or occasional flooding.
USE AND VEGETATION: Cropland and livestock grazing; crops are small grains, irrigated pasture and rice; vineyards, fruit and nut crops.
DISTRIBUTION AND EXTENT: Eastern side of the Sacramento and San Joaquin Valleys. The soils are extensive in MLRA-17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Fresno County, California, 1900.
REMARKS: This soil series is bordering on the Typic Durixeralf subgroup. The type location of this series has been moved to better reflect the central concept as historically mapped. (Textures from lab data reflect slightly different values than field estimates. NSSL S83CA-077-042.)
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of 6 inches (Ap)
Argillic horizon - the zone from 16 to 26 inches (2Bt3, 2Bt4)
Duripan - the zone from 26 to 60 inches (2Bqm1, 2Bqm2, 2Bq)