LOCATION SELMAC OREstablished Series
TAXONOMIC CLASS: Fine-loamy over clayey, mixed over smectitic, superactive, mesic Ultic Haploxeralfs
TYPICAL PEDON: Selmac loam, forested. (Colors are for moist soil unless otherwise noted.)
A--0 to 6 inches; dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; moderate medium granular and moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine vesicular and tubular pores; 15 percent gravel; strongly acid (pH 5.4); clear smooth boundary. (5 to 8 inches thick)
BA--6 to 10 inches; dark yellowish brown (10YR 3/4) clay loam, yellowish brown (10YR 5/4) dry; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; common fine to coarse roots; many very fine tubular pores; 10 percent gravel; strongly acid (pH 5.4); clear wavy boundary. (0 to 4 inches thick)
Bt--10 to 18 inches; reddish brown (5YR 4/4) gravelly clay loam, brown (7.5YR 5/4) dry; moderate fine subangular blocky structure; hard, friable, sticky and plastic; common fine and medium roots; common fine tubular pores; few distinct and common faint dark reddish brown (5YR 3/4) clay films on faces of peds; 20 percent gravel and 5 percent cobbles; strongly acid (pH 5.3); abrupt wavy boundary. (4 to 8 inches thick)
2C1--18 to 28 inches; olive brown (2.5Y 4/4) clay, light brownish gray (2.5Y 6/2) dry; massive; extremely hard, extremely firm, very sticky and very plastic; few coarse roots; few very fine tubular pores; common fine distinct dark brown (7.5YR 4/4) masses of iron accumulation in fractures; few small black concretions; common fine to coarse slickensides; moderately acid (pH 5.6); gradual smooth boundary. (8 to 12 inches thick)
2C2--28 to 47 inches; olive gray (5Y 5/2) clay, light olive gray (5Y 6/2) dry; massive; extremely hard, extremely firm, very sticky and very plastic; few coarse roots; few fine tubular pores; common fine to coarse slickensides with few intersecting; moderately acid (pH 5.8); clear smooth boundary. (15 to 20 inches thick)
2C3--47 to 60 inches; olive brown (2.5Y 4/4) and olive gray (5Y 4/2) clay, light olive gray (5Y 6/2) dry; massive; extremely hard, extremely firm, very sticky and very plastic; few small black stains; moderately acid (pH 5.9).
TYPE LOCATION: Josephine County, Oregon; 80 feet north and 50 feet west of the junction of Lind Road and Riverbanks Road and about 7 miles west of Grants Pass and about 80 feet north and 1,915 feet east of the southwest corner of sec. 13, T. 36 S., R. 7 W.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry between depths of 4 and 12 inches for 80 to 110 consecutive days during the summer. The mean annual soil temperature is 52 to 57 degrees F. The thickness of the solum above the nonconforming 2C clay horizon is 12 to 36 inches. Depth to bedrock is 60 inches or more. The solum is strongly acid or moderately acid.
The A horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 through 4 moist and 3 or 4 dry. It has 22 to 27 percent clay and 5 to 15 percent gravel. It has 1 to 3 percent organic matter.
The Bt horizon has hue of 10YR, 7.5YR or 5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and dry. It is clay loam or gravelly clay loam with 27 to 35 percent clay. It has 10 to 20 percent gravel and 0 to 10 percent cobbles. A stone line is at the base of the solum in some pedons.
The 2C horizon has hue of 2.5Y or 5Y, value of 4 or 5 moist, 6 or 7 dry, and chroma of 2 through 4 moist and dry. It is clay or silty clay with 55 to 70 percent clay. The increase in clay from the Bt horizon is more than 25 percent. It is moderately acid or slightly acid.
COMPETING SERIES: These are the Langellain and Sutherlin series. Langellain soils are 20 to 40 inches to a paralithic contact. Sutherlin soils are dry for less than 80 consecutive days.
GEOGRAPHIC SETTING: The Selmac soils are in drainage basins and have slopes of 2 to 20 percent. Elevations are 800 to 2,500 feet. The soils formed in stratified loamy and clayey mixed alluvium. The climate is characterized by hot, dry summers and cool, moist winters. The mean annual precipitation is typically 25 to 60 inches but ranges to 90 inches in Curry County, Oregon. The mean annual temperature is 50 to 56 degrees F, the mean January temperature is 39 degrees F, and the mean July temperature is 70 degrees F. The frost-free period is 140 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abegg, Josephine, Manita, Pollard and Ruch soils. All of these soils lack contrasting textures in the control section. Abegg soils are loamy-skeletal. Josephine and Ruch soils are fine-loamy and the Manita and Pollard soils have a clayey argillic horizon.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; very slow permeability. A water table is at a depth of 1.5 to 3.0 feet from the soil surface from December to May.
USE AND VEGETATION: These soils are used for pasture, hay and timber production. Native vegetation is Douglas fir, ponderosa pine, California black oak, Pacific madrone, poison oak, Idaho fescue and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southwestern Oregon; MLRA 5. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Josephine County, Oregon, 1979.
REMARKS: Formerly classified as fine-loamy over clayey, mixed, mesic Ultic Haploxeralfs, competing series not updated at the time of reclassification.
Diagnostic horizons and features recognized in this pedon:
Ochric epipdon
Argillic horizon - from 10 to 18 inches (Bt horizon)
Particle-size control section - from 10 to 40 inches (Bt, 2C1, and upper 2C2 horizons) with an absolute difference of 25 percent or more between clay percentages between the Bt and 2C1 horizons.