LOCATION TRAHERN CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Natric Duraquolls
TYPICAL PEDON: Trahern clay loam on less than 1 percent slope under cultivation at 30 feet elevation. (Colors are for dry soil unless otherwise noted. When described on May 27, 1977, the soil was dry from 0 to 7 inches and moist below.)
Ap--0 to 7 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine interstitial pores and few very fine tubular pores; mildly alkaline (pH 7.8); clear smooth boundary. (3 to 7 inches thick)
A--7 to 14 inches; gray (10YR 5/1) clay loam, very dark gray (10YR 3/1) moist; common fine distinct brown (10YR 5/3) mottles, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; few very fine tubular and interstitial pores; slightly effervescent with disseminated lime; moderately alkaline (pH 8.2); clear wavy boundary. (4 to 7 inches thick)
Btn1--14 to 20 inches; light brownish gray (10YR 6/2) and gray (10YR 6/1) clay, very dark grayish brown (10YR 3/2) and dark grayish brown (10YR 4/2) moist; moderate coarse prismatic structure parting to moderate medium and coarse subangular blocky; very hard, firm, very sticky and very plastic; common very fine and fine roots; common very fine tubular and few fine interstitial pores; common thin clay films on ped faces and lining pores; light gray (10YR 7/1) uncoated sand grains as coatings less than 2mm thick on tops and sides of some peds in the upper part of this horizon; slightly effervescent with disseminated lime; strongly alkaline (pH 8.6); clear wavy boundary. (5 to 6 inches thick)
Btn2--20 to 28 inches; pale brown (10YR 6/3) and light brownish gray (10YR 6/2) clay, brown (10YR 4/3) and dark brown (10YR 3/3) moist; moderate coarse prismatic structure parting to moderate medium and coarse subangular blocky; very hard, firm, very sticky and very plastic; few very fine and fine roots; common very fine tubular and few fine tubular and interstitial pores; many thin clay films on ped faces and lining pores; slightly effervescent with disseminated lime; strongly alkaline (pH 9.0); gradual wavy boundary. (4 to 8 inches thick)
Btn3--28 to 33 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; moderate medium angular blocky structure; hard, friable, very sticky and plastic; few very fine and fine roots; common very fine tubular and few fine tubular and interstitial pores; common thin clay films on ped faces and lining pores; slightly effervescent with disseminated lime; strongly alkaline (pH 8.8); clear wavy boundary. (4 to 5 inches thick)
Bk--33 to 38 inches; light grayish brown (10YR 6/2) clay loam, dark grayish brown (10YR 4/2) moist; few fine distinct light yellowish brown (10YR 6/4) mottles, dark yellowish brown (10YR 4/4) moist; moderate medium angular blocky structure; very hard, firm, sticky and plastic; very few very fine and fine roots; common very fine tubular and few fine tubular and interstitial pores; strongly effervescent with common fine filaments and soft masses of lime; moderately alkaline (pH 8.2); abrupt irregular boundary. (0 to 5 inches thick)
Bqkm--38 to 60 inches; light brownish gray (2.5Y 6/2) strongly cemented duripan, dark grayish brown (2.5Y 4/2) moist; common fine distinct light yellowish brown (2.5Y 6/4) and light olive brown (2.5Y 5/6) mottles, olive brown (2.5Y 4/4) moist; moderate medium platy structure in upper 1 to 2 inches, massive below indurated in upper part, strongly cemented below; no roots observed.
TYPE LOCATION: San Joaquin County, California; approximately 5.5 miles south of Manteca, 475 feet south and 150 feet east of the northwest corner of Sec.5, T.3S., R.7E., MDBM., Ripon quadrangle.
RANGE IN CHARACTERISTICS: Depth to duripan is 20 to 40 inches. The mean annual soil temperature is 62 to 63 degrees F. The soil between the depth of 5 to 20 inches is not dry at any time unless artificially drained. The weighted average clay content of the texture control section from a depth of 10 inches to the duripan is 35 to 60 percent.
The A horizon is 10YR 5/2, 5/1 or 4/1. Moist color is 10YR 3/2 or 3/1. Distinct or prominent mottles are present in the lower part of the A horizon. Clay content is 27 to 35 percent. Organic matter is 1 to 2 percent.
The Btn horizon is 2.5Y 6/2; 10YR 6/1, 6/2, 6/3 or 5/3. Moist color is 2.5Y 4/2; 10YR 4/1, 4/2, 4/3, 3/2 or 3/3. The upper part has columnar or prismatic structure with 45 to 60 percent clay, and the exchangeable sodium percentage is 15 to 25 percent. The lower part has 30 to 40 percent clay.
When a Bk horizon is present, it has similar colors as the Bt horizon. Clay content is 30 to 40 percent and textures are clay loam or silty clay loam. Reaction is moderately or strongly alkaline.
The Bkqm horizon is at depths of 20 to 40 inches. It is indurated in the upper part and cementation decreases with increasing depth. It is 10YR 6/1, 6/2, 6/3 or 2.5Y 6/2. Moist color is 10YR 4/1, 4/2, 4/3; 2.5Y 4/2; 5Y 5/1, 5/2; 5GY 5/2 or 6/2. Distinct or prominent mottles are present.
COMPETING SERIES: There are no other soils in this family.
GEOGRAPHIC SETTING: Trahern soils are on nearly level low terraces. Slopes are 0 to 2 percent. The soils formed in alluvium from mixed rock sources. Elevation is 20 to 40 feet. The climate is subhumid mesothermal with hot dry summers and cool moist winters. Mean annual precipitation is 11 to 12 inches mean January temperature is 45 degrees F; mean July temperature is 77 degrees F; mean annual temperature is 60 or 61 degrees F. Frost-free season averages from 250-280 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Manteca, Tinnin and Veritas soils. Manteca and Veritas soils have coarse-loamy control sections. Tinnin soils have sandy control sections.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; very slow permeability.
USE AND VEGETATION: These soils are used for irrigated cropland and pasture. Alfalfa, barley and corn are the principal crops. Natural vegetation is annual grasses, forbs and scattered valley oaks.
DISTRIBUTION AND EXTENT: Trahern soils occur in the northeastern San Joaquin Valley. The soils are not extensive in MLRA-17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: San Joaquin County, California 1989.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 14 inches (Ap,A)
Natric horizon - 14 to 28 inches (Btn1,Btn2) E.S.P. is more than 15 in some part.
Duripan - the zone from 38 to 60 inches (Bkqm)