LOCATION WINNIBULLI CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aquultic Argixerolls
TYPICAL PEDON: Winnibulli loam - on a northeast facing slope of 2 percent under a cover of ponderosa pine and Oregon white oak at an elevation of 3,320 feet. (Colors are for dry soil unless stated otherwise. When described on September 3, 1981, the soil was moist below 87 inches.)
Oi--2 to 0 inches; recent and slightly decomposed pine and oak litter.
A1--0 to 2 inches; dark brown (10YR 4/3) loam, dark brown (7.5YR 3/2) moist; strong fine platy structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; moderately acid (pH 6.0); abrupt smooth boundary.
A2--2 to 5 inches; dark brown (10YR 4/3) loam, dark reddish brown (5YR 3/3) moist; weak medium subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; few fine roots; common very fine tubular and few medium vesicular pores; moderately acid (pH 6.0); abrupt smooth boundary. (Combined thickness of the A horizon is 4 to 7 inches)
BAt--5 to 11 inches; dark brown (7.5YR 4/4) loam, dark reddish brown (5YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and many medium roots; few fine and common very fine tubular pores; few thin clay films on peds and common thin clay films in pores; moderately acid (pH 6.0); clear smooth boundary.
Bt1--11 to 24 inches; reddish brown (5YR 4/4) clay loam, dark reddish brown (5YR 3/4) moist; few fine distinct black (N 2/0) redox concentrations, black (N 2/0) moist; moderate medium subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; many fine and medium and common coarse roots; many fine and common medium tubular pores; common thin clay films on peds and common moderately thick clay films in pores; slightly acid (pH 6.5); clear smooth boundary.
Bt2--24 to 38 inches; brown (7.5YR 5/4) clay loam, dark brown (7.5YR 4/4) moist; few fine distinct red (2.5YR 5/6) masses of iron accumulation, dark red (2.5YR 3/6) moist; moderate medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; many medium and common coarse roots; many very fine and common medium tubular pores; common thin clay films on peds and common moderately thick clay films in pores; slightly acid (pH 6.5); gradual wavy boundary.
Bt3--38 to 45 inches; light yellowish brown (10YR 6/4) clay loam, dark yellowish brown (10YR 4/4) moist; few fine distinct black (N 2/0) and strong brown (7.5YR 5/6) redox concentrations, black (N 2/0) and dark brown (7.5YR 4/4) moist; strong medium subangular blocky structure; hard, firm, slightly sticky and plastic; few fine and medium roots; many very fine and common fine tubular pores; few moderately thick and many thin clay films on peds and moderately thick clay films in pores; slightly acid (pH 6.5); clear smooth boundary.
Bt4--45 to 55 inches; light gray (10YR 7/2) clay loam, brown (10YR 5/3) moist; few fine distinct black (N 2/0) and many medium distinct strong brown (7.5YR 5/6) redox concentrations, few fine black (N 2/0) and many medium dark brown (7.5YR 4/4) moist; moderate fine subangular blocky structure; very hard, very firm, sticky and plastic; few fine and coarse and many medium roots; common very fine tubular pores; common thin clay films on peds and few moderately thick clay films in pores; slightly acid (pH 6.5); abrupt smooth boundary. (Combined thickness of the Bt horizon is 8 to 45 inches)
Btg1--55 to 63 inches; light gray (10YR 7/2) sandy clay loam, brown (10YR 5/3) moist; few fine distinct black (N 2/0) and many medium distinct strong brown (7.5YR 5/6) mottles, few fine black (N 2/0) and many medium dark brown (7.5YR 4/4) moist; moderate coarse angular blocky structure; extremely hard, firm, slightly sticky and slightly plastic; weakly cemented; common very fine tubular pores; common thick clay films on peds and common thin clay films in pores; discontinuous manganese and silica laminar capping 1/4 to 1/8 inch thick; slightly acid (pH 6.5) gradual smooth boundary. (5 to 12 inches thick)
Btg2--63 to 72 inches; pink (7.5YR 7/4) sandy clay loam, dark brown (7.5YR 4/2) many medium prominent black (N 2/0) mottles, black (N 2/0) moist; weak fine subangular blocky structure; very hard, firm, slightly sticky and slightly plastic; common very fine tubular pores; common thin clay films on peds and in pores and common thick clay films in bridges between mineral grains; slightly acid (pH 6.5); abrupt smooth boundary. (9 to 19 inches thick)
Bq--72 to 87 inches; very dark gray(5YR 3/1) sandy loam, reddish black (5YR 2.5/1) moist; massive; hard, firm, nonsticky and nonplastic; weakly cemented; discontinuous manganese and silica laminar capping 1/8 to 1/16 inch thick; neutral (pH 6.8); clear smooth boundary.
TYPE LOCATION: Shasta County, California; about 1.5 miles southeast of Dana on McArthur Road, about 800 feet west and 400 feet south of the northeast corner of section 31, T.38N., R.4E., Pondosa SE (Dana) Quadrangle (7.5 minute series).
RANGE IN CHARACTERISTICS: Depth to weakly cemented horizon is 40 to greater than 60 inches. The mean annual soil temperature is 47 to 49 degrees F. The soil temperature exceeds 41 degrees F from about March 15 to about December 31 (285 days) and exceeds 47 degrees F from about May 15 to about November 30 (195 days). The soil moisture control section (6 to 17 inches) is moist throughout from about December 1 to about April 30 and is dry throughout from about July 1 until about October 31 (125 days). Distinct or prominent mottles are present from 12 to 60 inches. Some pedons are underlain by extremely gravelly sandy loam. Organic matter ranges from .6 to 5 percent to a depth of 10 to 15 inches. Base saturation (ammonium acetate) ranges from 55 to 68 percent to a depth of 33 inches and greater than 75 percent below. A water table is within 40 inches for 150 days.
The A horizon color is 10YR 4/2, 4/3, 5/3; 7.5YR 5/4. Moist color is 10YR 2/2 or 7.5YR 3/2, 5YR 3/3. Gravel ranges from 0 to 5 percent. Reaction is moderately acid to neutral.
The Bt horizon color is 10YR 4/3, 6/4, 7/2; 7.5YR 4/4, 5/4, 6/4, 7/2; or 5YR 4/4, 5/4. Moist color is 10YR 4/4, 5/3; 7.5YR 3/2, 3/4, 4/2, 4/4, 5/4; or 5YR 3/2, 3/3, 3/4, 4/4. It is clay loam or sandy clay loam with a clay content between 27 to 35 percent. Gravel ranges from 0 to 25 percent. Reaction is slightly acid to neutral.
COMPETING SERIES: These are no competing soils.
GEOGRAPHIC SETTING: Winnibulli soils are on alluvial fans and fan terraces. Slopes are 0 to 5 percent. The soils formed in alluvium from extrusive igneous rock. Elevation is 3,200 to 4,500 feet. Climate is subhumid with warm dry summers and cold moist winters. The mean annual precipitation is 25 to 35 inches. Snowfall is 24 to 48 inches. Mean annual temperature is 45 to 48 degrees F. Frost-free season is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dudgen (T), Graven (T) and Jimmerson (T) soils. Dudgen soils are 10 to 20 inches deep to duripan on intermounds. Graven (T) soils are 20 to 40 inches deep to duripan on intermounds. Jimmerson soils have a solum thickness greater than 60 inches on hills.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained, slow runoff, moderately slow permeability in the upper 55 inches and slow in the underlying material. A fluctuating water table occurs at depths of 18 to 48 inches from December 1 through April 30 and is below 60 inches June through November. Occasional flooding occurs from January to April.
USE AND VEGETATION: These soils are used for timber production and grazing. Present vegetation is Ponderosa pine, Oregon white oak, California Black Oak, and perennial grasses.
DISTRIBUTION AND EXTENT: Northeastern California. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Shasta County, Intermountain Soil Survey, California 1994. Source of name is from Winnibulli Mountain.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to a depth of about 11 inches (A1, A2, BAt horizons).
Argillic horizon - the zone from 11 to 72 inches (BAt, Bt1, Bt2, Bt3, Bt4, Btg1 and Btg2 ). The particle-size control section is from 11 to 31 inches.
ADDITIONAL DATA: A nearby pedon was sampled by U.C. Davis in 1973. Pedon number is 73-45-180X, unpublished.