LOCATION SIBOLD OREstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aquultic Argixerolls
TYPICAL PEDON: Sibold fine sandy loam - pasture, on a 1 percent slope at an elevation of 590 feet. (Colors are for moist soil unless otherwise stated.)
A1--0 to 6 inches; dark brown (10YR 3/3) fine sandy loam, brown (10YR 5/3) dry; moderate fine and medium subangular blocky structure parting to moderate very fine and fine granular; slightly hard, friable, slightly sticky and non plastic; many very fine and fine roots; many very fine and fine discontinuous tubular pores; many fine distinct strong brown (7.5YR 5/8) masses of iron accumulation; strongly acid (pH 5.5); clear smooth boundary.
A2--6 to 12 inches; dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; moderate medium and coarse subangular blocky structure parting to fine and medium subangular blocky; hard, firm, slightly sticky and slightly plastic; many fine and very fine roots; many very fine and fine and few medium continuous tubular pores; many fine and medium distinct strong brown (7.5YR 5/8) masses of iron accumulation; strongly acid (pH 5.5); gradual smooth boundary. (Combined thickness of the A horizon is 10 to 16 inches)
Bw--12 to 19 inches; dark yellowish brown (10YR 4/4) loam, light yellowish brown (10YR 6/4) dry; weak medium prismatic structure parting to moderate fine and medium subangular blocky; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine and few medium continuous tubular pores; many fine and medium distinct strong brown (7.5YR 5/8) masses of iron accumulation and many fine and medium distinct light brownish gray (10YR 6/2) iron depletions, few fine and medium very dark gray (10YR 3/1) manganese stains; strongly acid (pH 5.5); gradual smooth boundary. (0 to 10 inches thick)
Bt1--19 to 40 inches; dark yellowish brown (10YR 4/4) loam, light yellowish brown (10YR 6/4) dry; weak coarse prismatic structure parting to moderate medium and coarse subangular blocky; hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine, fine, and medium continuous tubular pores; many distinct and few prominent dark brown (7.5YR 4/4) clay films on faces of peds, lining pores, and bridging sand grains; many fine and medium distinct strong brown (7.5YR 5/8) masses of iron accumulation and many fine and medium distinct light brownish gray (10YR 6/2) iron depletions, few fine and medium very dark gray (10YR 3/1) manganese stains, strongly acid (pH 5.5); clear smooth boundary.
Bt2--40 to 49 inches; yellowish brown (10YR 5/6) loam, light yellowish brown (10YR 6/4) dry; moderate fine and medium subangular structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine and few medium continuous tubular pores; common distinct and few prominent dark brown (7.5YR 4/4) clay films on faces of peds, lining pores, and bridging sand grains; many fine and medium distinct strong brown (7.5YR 5/8) masses of iron accumulation and many fine and medium distinct light brownish gray (10YR 6/2) iron depletions, few fine and medium very dark gray (10YR 3/1) manganese stains; strongly acid (pH 5.5); gradual smooth boundary. (Combined thickness of the Bt horizon is 25 to 40 inches)
2Bt3--49 to 63 inches; brownish yellow (10YR 6/6) silty clay, yellow (10YR 7/6) dry; weak coarse and very coarse subangular blocky structure; very hard, very firm, very sticky and very plastic; few very fine roots; many fine, medium, and coarse continuous and tubular pores; common prominent dark yellowish brown (10YR 4/6) clay films lining pores, and common faint yellowish brown (10YR 4/6) clay films on faces of peds; many medium and coarse distinct strong brown (7.5YR 5/8) masses of iron accumulation and many medium distinct light brownish gray (10YR 6/2) iron depletions, common fine very dark gray (10YR 3/1) manganese stains; strongly acid (pH 5.5).
TYPE LOCATION: Douglas County, Oregon, 1 1/2 miles southwest of the town of Lookingglass, about 2100 feet west and 500 feet south of the northeast corner of section 3, T. 28 S., R. 7 W. (Latitude 43 degrees, 10 minutes, 48 seconds N, Longitude 123 degrees, 31 minutes, 14 seconds W.)
RANGE IN CHARACTERISTICS: The soil is dry in all parts of the moisture control section for 50 to 90 consecutive days following the summer solstice. The mean annual soil temperature is 52 to 56 degrees F. Depth to bedrock is more than 60 inches. The particle size control section has 25 to 35 percent clay. Depth to high chroma iron accumulations is 20 to 30 inches, and depth to depletions having chroma of 2 or less is 12 to 30 inches. Depth to the clayey discontinuity (2Bt) is 40 to over 60 inches.
The A horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 3 moist and 2 or 4 dry. It has 0 to 10 percent gravel.
The Bt horizon has value of 4 or 5 moist, 5 or 6 dry, and chroma of 3 to 6 moist and dry. It is loam or clay loam, with 25 to 35 percent clay. It has 0 to 10 percent gravel and 0 to 5 percent cobbles.
The 2Bt horizon, when present, has hue of 10YR or 2.5Y, value of 5 to 7 moist, 6 or 7 dry, and chroma of 5 to 7 moist and dry. It is silty clay or clay, with 40 to 55 percent clay. It is strongly or very strongly acid.
COMPETING SERIES: This is the Winnibulli (T) series. Winnibulli soils are dry in the moisture control section for greater than 125 days, have a weakly cemented horizon from 40 to greater than 60 inches, and the mean annual soil temperature is 47 to 49 degrees F.
GEOGRAPHIC SETTING: Sibold soils are on high flood plains. The soils formed in mixed alluvium. Slopes are 0 to 5 percent. Elevations are 100 to 2000 feet. The climate is characterized by warm, wet winters and hot, dry summers. The mean annual temperature is 50 to 55 degrees F. The mean annual precipitation is 30 to 60 inches. The frost-free period is 160 to 235 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chapman, Chehalis, Coburg, Conser, Evans, Malabon, Newberg, Redbell, Roseburg, and Waldo soils. Chapman and Chehalis lack argillic development and are on flood plains. Coburg and Malabon soils are fine and are on flood plains and terraces. Conser soils are fine and are on terraces. Evans and Newberg soils are coarse-loamy and are on flood plains. Redbell soils are fine and on terraces. Roseburg soils are well drained and on terraces. Waldo soils are poorly drained and fine textured and are on flood plains.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; Permeability is moderately slow over very slow. Flooding is rare. There is a perched water table at 0.5 to 1.5 feet from November to May.
USE AND VEGETATION: These soils are used for hay and pasture, cropland, wildlife habitat, and water supply. In areas not cultivated, native vegetation is Oregon white oak, Oregon ash, rose, common snowberry, Saskatoon serviceberry, sedge, and blue wildrye.
DISTRIBUTION AND EXTENT: Southwestern Oregon, MLRA 5. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Douglas County, Oregon, 1994.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to 12 inches. (A1 and A2 horizons)
Argillic horizons - from 19 to 63 inches. (Bt1, Bt2, and 2Bt3 horizons)
Base saturation is assumed to be 50 to 75 percent in some part of the upper 30 inches of the solum.
Redox depletions with chroma of 2 or less below 12 inches. (Bw, Bt1, Bt2, 2Bt horizons)
Particle size control section - from 19 to 39 inches.
The superactive cation exchange activity class was added to the classification in 10/2005. The competing series section was not updated at that time. Last revision 3/1995.
ADDITIONAL DATA: Laboratory data is available for the Roseburg series, a soil that is geographically associated with Sibold. Reference samples S59 Oreg-10-6-1 through 8 (Riv.Lab.Nos. 59447 - 59454), and S59 Oreg-10-7-1 through 7 (Riv.Lab.Nos. 59455 - 59461) from Douglas County, Oregon, Riverside, CA, 1959.