LOCATION DOSA CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Xeric Epiaquerts
TYPICAL PEDON: Dosa silty clay loam on a southeast facing 1 percent slope under a cover of rushes, and sedges at an elevation of 4090 feet. (Colors are for dry soil unless, otherwise stated. When described July 26, 1989, the soil was slightly moist throughout.)
A- 0 to 4 inches; gray (10YR 6/1) silty clay loam, dark gray (10YR 4/1) moist; weak very fine subangular blocky structure; soft, very friable, slightly sticky and plastic; many very fine roots; few very fine interstitial pores; cracks 1/2 inch wide; slightly acid (pH 6.1); abrupt smooth boundary. (2 to 6 inches thick)
Bss1- 4 to 17 inches; light brownish gray (10YR 6/2) clay, dark grayish brown (10YR 4/2) moist, common fine distinct strong brown (7.5YR 5/6), dark grayish brown (10YR 3/6) moist masses of iron accumulation; strong coarse prismatic structure; extremely hard, extremely firm, sticky and plastic; few very fine and common fine roots; few very fine tubular pores; cracks 1/2 inch wide; common intersecting slickensides slightly acid (pH 6.1); abrupt smooth boundary.
Bss2- 17 to 28 inches; light brownish gray (10YR 6/2) clay, dark grayish brown (10YR 4/2) moist, many medium distinct dark yellowish brown (10YR 4/6) and dark red (2.5YR 3/6), dark yellowish brown (10YR 3/6) moist masses of iron accumulation; strong coarse prismatic structure; extremely hard, extremely firm, sticky and plastic; few fine and common very fine roots; few very fine tubular pores; craks 1/2 inch wide; common intersecting slickensides 10 percent gravel; mildly alkaline (pH 7.5); clear smooth boundary. (Combined thickness of the Bss horizons is 18 to 36 inches)
2Cr1- 28 to 37 inches; weathered diatomaceous earth; white 10YR 8/2), light gray (10YR 7/2) moist; few very fine and fine roots; moderately alkaline (pH 8.0); abrupt wavy boundary. (8 to 12 inches thick)
2Cr2--37 to 41 inches; diatomaceous earth with a few fractures filled with clay; mildly alkaline (pH 8.0); abrupt wavy boundary. (4 to 8 inches thick)
2Cr3- 41 to 72 inches; diatomaceous earth with clay in fractures; moderately alkaline (pH 8.0).
TYPE LOCATION: Shasta County, California; about 2.7 miles southeast of Pondosa, approximately 1200 feet South and 1800 feet West of the northeast corner of Section 6, T.38N., R.3E. Pondosa NW (Pondosa) Quadrangle (7.5 minute series).
RANGE IN CHARACTERISTICS: Depth to paralithic contact is 20 to 40 inches. The mean annual soil temperature is 47 to 52 degrees F. The soil temperature exceeds 41 degrees F. from early March to late December and exceeds 47 degrees F. from mid April to mid November. The soil moisture control section (6 to 19 inches) is dry in all parts from mid August to late September (40 to 50 days) and is moist in all parts from early December to early July. The particle-size control section (10 to 28 inches) ranges from 45 to 55 percent clay. Cracks 1/2 to 3/4 inches wide extend to a depth of 28 to 30 inches when the soil is dry from about July 15 to about September 30 (60 to 80 days).
The A horizon color is 10YR 6/1, 6/2, or 7/2. Moist color is 10YR 4/1, or 4/2. Organic matter ranges from 2 to 3 percent. Clay content ranges from 35 to 40 percent.
The Bss horizon color is 10YR 6/1, 6/2, or 7/1. Moist color is 10YR 4/1, or 4/2. Organic matter ranges from 1 to 2 percent. Texture is clay or silty clay. Clay content ranges from 45 to 55 percent. Rock fragments, mostly fine gravel range from 0 to 10 percent. Reaction is slightly acid in the upper part and neutral to mildly alkaline in the lower part.
COMPETING SERIES: These are the Lasvar (TCA), Piline (NV), and Pitvar (T CA) series. Lasvar soils are 20 to 40 inches deep to a duripan. Piline soils are very deep and Pitvar soils are 40 to 60 inches deep to a duripan.
GEOGRAPHIC SETTING: Dosa soils are on terraces. Slopes are 0 to 2 percent. These soils formed in alluvium and material weathered from lake sediments. Elevation is 3200 to 5500 feet. The climate is subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 35 to 50 inches. Snowfall is 30 to 50 inches. The mean annual temperatures is 45 to 50 degrees F. The mean January temperature is about 32 degrees F. The mean July temperature is about 65 degrees F. Frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jimmerson and Wyntoon soils. Jimmerson soils are on lava plateaus and hills, are very deep, argillic horizon, have weakly expressed andic properties in the upper 24 inches, and are medial over loamy. Wyntoon soils are on hills and terraces, are very deep, argillic horizon and have moderate andic properties in the upper 25 inches and are medial over loamy.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; ponded to very slow runoff; slow permeability. Ponding occurs at depths of 6 inches above the surface from December through April. A perched water table occurs at depths of 0 to 30 inches from December through July.
USE AND VEGETATION: This soil is used for livestock grazing. The vegetation is rushes, sedges, bluegrass, bentgrass, tufted hairgrass and perennial forbs.
DISTRIBUTION AND EXTENT: Northeastern California. The soils are not extensive. MLRA is 22.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Shasta County, Intermountain Big Valley Soil Survey Area, California 1994. Source of name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:Ochric epipedon - the zone from the surface to 4 inches (A)
Paralithic contact - the boundary at 28 inches. (Cr)