LOCATION BOSANKO CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Aridic Haploxererts
TYPICAL PEDON: Bosanko clay - annual grass pasture (Colors are for dry soil unless otherwise noted).
Ap--0 to 5 inches; gray (10YR 5/1) clay, very dark gray (10YR 3/1) moist; moderate and fine granular structure; very hard, firm, sticky, plastic; many very fine and fine roots; many very fine and fine tubular and interstitial pores; slightly acid (pH 6.3); abrupt smooth boundary. (4 to 6 inches thick)
Bss1--5 to 18 inches; gray (10YR 5/1) clay, very dark gray (10YR 3/1) moist; strong medium and coarse angular blocky structure; extremely hard, very firm, very sticky, very plastic; many very fine, common fine roots; common very fine and fine tubular pores; many slickensides; neutral (pH 6.7); clear smooth boundary. (12 to 16 inches thick)
Bss2--18 to 23 inches; gray (10YR 6/1) clay, very dark gray (10YR 3/10 moist; moderate medium angular blocky structure; very hard, firm, very sticky, very plastic; common very fine roots; common very fine, few fine tubular pores; many slickensides; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 6 inches thick)
Bk--23 to 30 inches; brown (10YR 5/3) heavy sandy clay loam, dark brown (10YR 4/3) moist; weak medium angular blocky structure; hard, friable, sticky, plastic; few very fine roots; common very fine tubular pores; slightly effervescent, disseminated lime, violently effervescent white (10YR 8/1) rounded soft masses, moderately alkaline (pH 8.2); clear irregular boundary. (5 to 11 inches thick)
Cr--30 to 48 inches; pale brown (10YR 6/30 decomposed acid igneous rock.
TYPE LOCATION: San Diego County, California; about 1 1/2 miles north of Ramona; approximately 3,700 feet north, 140 feet west of intersection of Haverford and Lilac Roads; SW 1/4, NE 1/4, sec. 3, T. 13 S., R. 1 E.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact of weathered igneous and sedimentary rock is 40 inches. The mean annual soil temperature at a depth of 20 inches is about 65 degrees F. Soil between the depths of about 4 and 12 inches usually is moist in some or all parts from about December 1 until sometime in May and usually is dry all the rest of the year. During the period soil cracks 3/8 to 1 inches wide extend from the surface to a depth of 20 to 40 inches. Usually the cracks remain closed from initial wetting until about April or May. Rock fragments make up about 1 to 5 percent of the upper horizons and up to about 15 percent of the lower horizons. Most fragments are 2mm up to about 3/4 inches in diameter. In some pedons the immediate surface has a layer of cobblestones and large stones. A few to many slickensides are present from the bottom of the Ap horizon or from about a depth of 5 inches down to 20 inches or to the top of the C horizon. The A horizon is gray or dark gray in 10YR hue. In some pedons the lower part is grayish brown or dark grayish brown. This horizon is clay loam or clay and has on the average 30 to 45 percent cay. It is mildly alkaline to medium acid in the upper part and neutral to moderately alkaline in the lower part. The C horizon is brown, grayish brown, pale olive or olive brown. It is clay loam, sandy clay loam, clay or sandy clay and is mildly or moderately alkaline. Segregated lime in this horizon ranges from a very small amount of white powder to many distinct soft rounded masses and blotches. In some pedons the transition from A to C horizons consists of an AC or an ACca horizon.
COMPETING SERIES: These are the Alo, Auld, Centerville, Cibo, Climara, Cropley, and Diablo series. Alo, Auld, Centerville, and Cibo soils have chroma of 2 or more throughout the soil profile. Also, Auld soils are reddish in 5YR hue. Centerville soils have hue of 7.5YR or 5YR. Cibo soils have a lithic contact at a depth of 24 to 40 inches. Climara soils have a lithic contact and a low Ca/Mg ratio of about 2. Cropley soils lack a paralithic contact. Diablo soils have a paralithic contact at a depth of 40 to 80 inches.
GEOGRAPHIC SETTING: The Bosanko soils are gently sloping to moderately steep and are in the uplands at elevations of about 300 to 2,500 feet. The soils formed in residuum weathered from igneous rocks of granitic nature. The climate is dry subhumid mesothermal with long warm dry summers and short moist winters. The average annual precipitation is 12 to 18 inches. The average January temperature is 45 degrees F; the average July temperature is 70 degrees F, and the average annual temperature is 60 to 64 degrees F. The freeze-free season is 260 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Alo soils and the Fontana, Bonsall, Fallbrook, Ramona, and Vista soils. Fontana soils have chroma greater than 1.5 and lack slickensides. Bonsall soils have argillic horizons with an abrupt upper boundary. Fallbrook and Ramona soils have sandy loam to loam A horizons and reddish argillic horizons. Vista soils have sandy loam surface horizons and lack slickensides.
DRAINAGE AND PERMEABILITY: Well-drained; slow to rapid runoff depending on slope slow permeability after cracks swell shut.
USE AND VEGETATION: Used mostly for growing grain, grain-hay or pasture. Naturalized vegetation is mainly annual grasses and forbs.
DISTRIBUTION AND EXTENT: Foothills and interior valleys of the coastal part of southern California. The series is inextensive in MLRA 20d.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED; San Diego County, California, 1973.
REMARKS:
Last revised by the state on 7/74.
Series reclassified on September, 1994. Competing series not reviewed at that time.
ADDITIONAL DATA: Two pedons sampled in Orange County: NSSL pedons S71CA-059-013 and -014. They are in MLRA 19. A NSSL partial pedon S31CA-073-009 (type location); S64CA-073-008 and S64CA-073-009 (range in characteristics)