LOCATION STELLA WAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Palexeralfs
TYPICAL PEDON: Stella silt loam-under a coniferous forest on a 5 percent southwest facing convex slope at an elevation of 600 feet. The soil was moist when described. (Colors are for moist soil unless otherwise stated.)
Oi & Oa--1 to 0 inch; needles, leaves, and twigs in various stages of decomposition; abrupt smooth boundary. (0.5 to 1 inch thick)
A--0 to 11 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine granular subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many coarse, medium, and fine roots; many fine interstitial pores; common fine shot-like aggregates; strongly acid (pH 5.4); gradual wavy boundary. (9 to 14)
E1--11 to 20 inches; dark yellowish brown (10YR 3/4) silt loam, yellowish brown (10YR 5/4) dry; weak, fine, subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many coarse, medium, and fine roots; common fine tubular pores; common, fine, shot-like aggregates; very strongly acid (pH 4.8); gradual wavy boundary.
E2--20 to 25 inches; dark yellowish brown (10YR 4/4) silt loam, light yellowish brown (10YR 6/4) dry; moderate to weak, fine, subangular blocky structure; slightly hard, friable, sticky and plastic; few coarse and medium and common fine roots; common fine tubular pores; medium, distinct, yellowish red (5YR 5/6) and grayish brown (10YR 5/2) mottles, reddish yellow (7.5YR 7/6) and light gray (2.5Y 7/2) dry; few, fine, shot-like aggregates; strongly acid (pH 5.2); clear wavy boundary. (7 to 22 inches combined thickness of E horizon)
2Bt/E1--25 to 37 inches, dark brown (10YR 4/3) silty clay loam, light yellowish brown (10YR 6/4) dry; (B part) grayish brown (2.5Y 5/2) silt loam coatings on prism faces, about 1/16 to 3/4 inch thick, light gray (2.5Y 7/2) dry; (E part) moderate, medium prismatic and subangular blocky structure; very hard, very firm, sticky and plastic; few fine roots to a depth of 37 inches, mostly in the E part; many fine and common medium tubular pores; continuous faint clay films on peds and in pores; common black manganese concretions and stains; strongly acid (pH 5.2); irregular wavy boundary.
2Bt/E2--37 to 48 inches; dark brown (7.5YR 3/4) silty clay loam, strong brown (7.5YR 5/6) dry (B part); grayish brown (2.5Y 5/2) light silty clay loam coatings on prism faces, 1/16 to 3/4 inch thick, light gray (2.5Y 7/2) dry (E part); moderate, medium and coarse, prismatic and moderate medium angular blocky structure; very hard, very firm, sticky and plastic; many fine and common medium tubular pores; continuous faint clay films on faces of peds and in pores; many black manganese concretions and stains; strongly acid (pH 5.2); irregular wavy boundary. (17 to 30 inches combined thickness of 2B/E horizon)
2Bt--48 to 60 inches; dark brown (7.5YR 4/4) silty clay, brown (7.5YR 5/4) dry; moderately, medium and coarse subangular blocky structure; very hard, very firm, sticky and plastic; common fine and medium tubular pores; continuous prominent clay films on faces of peds and in pores; many black manganese concretions and stains; strongly acid (pH 5.4).
TYPE LOCATION: Cowlitz County, Washington. Approximately 8 miles northwest of Longview. About 75 feet north of Stella Road at a point about 0.9 miles northwest of the Stella-Wohl Road intersection. About 700 feet south and 2,600 feet east of the northwest corner of section 9, T. 8 N., R. 3 W.
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in the moisture control section for 45 to 60 consecutive days following summer solstice. The average annual soil temperature is 50 to 54 degrees F. Depth to the 2B/E horizon is 22 to 36 inches. Reaction is strongly acid through very strongly acid.
The A horizon has hue of 7.5YR or 10YR, value of 2 to 3, and chroma of 2 to 4 moist.
The E horizon has hue of 7.5YR or 10YR and value and chroma of 3 or 4 moist.
The Bt part of the 2Bt/E horizon ranges in hue from 5YR to 10YR.
The E part of the 2Bt/E2 horizon ranges in hue from 2.5Y to 5Y. Texture is silt loam or silty clay loam.
The 2Bt horizon has hue of 7.5YR or 5YR, value of 4 or 5 moist, 5 or 6 dry, and chroma of 4 to 6 moist and dry. Manganese stains or concretions are throughout the horizon.
COMPETING SERIES: These are the Galvin and Rose Valley series. Galvin soils do not have coatings of albic material in the argillic horizon. Rose Valley soils have chroma of 2 or less in the matrix of the lower part of the argillic horizon and are somewhat poorly drained.
GEOGRAPHIC SETTING: Stella soils are on broad ridgetops and hillsides at elevations of 300 to 700 feet. They developed in loess over old alluvium mostly from basic igneous rocks. The climate is characterized by warm, dry summers and cool, wet winters. The average annual precipitation is 45 to 55 inches. The mean January temperature is about 38 degrees F and in July it is 64 degrees F. The mean annual temperature is about 51 degrees F. The average growing season at 28 degrees F is 220 to 240 days. The frost free season 32 degrees F is 165 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Germany. Olequa, and Olympic soils and the competing Rose Valley soils. Germany and Olympic soils are well drained and are in a clayey family. Olequa soils are well drained and have a base saturation (by sum) of less than 35 percent 1.25 meters below the top of the argillic horizon.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow runoff; very slow permeability. A perched water table is as high as 2 to 3 feet at times from November through April.
USE AND VEGETATION: Used mostly for growing timber, some is used for cropland. Hay and pasture are the common crops. Some areas are used for rural homesites. Native vegetation is Douglas-fir, red alder, western hemlock, grand fir, bigleaf maple, and western redcedar with an understory of salmonberry, western brackenfern, western swordfern, salal, Oregongrape, trailing blackberry, and red huckleberry.
DISTRIBUTION AND EXTENT: Southwest Washington. Stella series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cowlitz County, Washington, 1989.
REMARKS: Diagnostic horizons and features recognized in this pedon are an umbric epipedon from the mineral surface to 11 inches, a zone of clay removal from 11 to 25 inches, and an argillic horizon from 25 to 60 inches. The upper part of the argillic horizon from 25 to 48 inches is coated with albic material on faces of peds. Base saturation (by sum) is assumed to be less than 75 percent in all parts of the argillic horizon and to be above 35 percent 1.25 meters below the top of the argillic horizon,based on laboratory data on the similar Rose Valley series, Number S84WA-015-009. This soil would be in an aqultic subgroup if such were provided in Soil Taxonomy.