LOCATION CENTRALIA WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Xeric Palehumults
TYPICAL PEDON: Centralia loam - forest, on a 20 percent convex southeast-facing shoulder slope at an elevation of 560 feet. (The soil was moist when described. Colors are for dry soil unless otherwise stated).
Oi--1.5 to 0.5 inch; loose, partially decomposed organic litter, including leaves, needles, twigs, bark, roots, and moss; abrupt smooth boundary. (1 to 3 inches thick where undisturbed)
Oe--0.5 inch to 0; decomposed organic material; abrupt smooth boundary. (1 to 3 inches thick where undisturbed)
Ac1--0 to 8 inches; very dark grayish brown (10YR 3/2) loam, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure parting to very fine and fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many fine, medium, and coarse roots; many very fine irregular pores; 5 percent shot-like aggregated (2-5 mm in diameter); strongly acid (pH 5.4); clear wavy boundary. (4 to 10 inches thick)
Ac2--8 to 17 inches; dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; weak medium subangular blocky structure parting to very fine and fine subangular blocky; hard, friable, slightly sticky and slightly plastic; many fine, medium, and coarse roots; many very fine, fine, and medium tubular pores; 5 percent shot-like aggregates (2-5 mm in diameter); moderately acid (pH 5.6); clear wavy boundary. (6 to 10 inches thick)
Bt1--17 to 26 inches; brown (10YR 4/3) clay loam; yellowish brown (10YR 5/4) dry; moderate fine and medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; many fine and medium tubular pores; common distinct clay films on faces of peds and lining pores; a few shot-like aggregates (2-5 mm in diameter); moderately acid (pH 5.6); clear wavy boundary. (6 to 10 inches thick)
Bt2--26 to 38 inches; dark yellowish brown (l0YR 4/4) clay loam, yellowish brown (l0YR 5/4) dry; moderate fine and medium subangular blocky structure; hard, firm, slightly sticky and plastic; common very fine and fine, few medium and coarse roots; many very fine and fine tubular pores; many distinct clay films on faces of peds and lining pores; strongly acid (pH 5.4) clear wavy boundary. (8 to 20 inches thick)
Bt3--38 to 49 inches; grayish brown (10YR 5/2) clay loam, light brownish gray (10YR 6/2) dry; few medium prominent dark yellowish brown (10YR 4/6) mottles, yellowish brown (10YR 5/6) dry; moderate coarse subangular blocky structure; hard, firm, sticky and plastic; few fine, medium, and coarse roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and lining pores; strongly acid (pH 5.0); clear wavy boundary. (0 to 12 inches thick)
BCt--49 to 60 inches; grayish brown (10YR 5/2) clay loam, light brownish gray (10YR 6/2) dry; common medium prominent yellowish red (5YR 5/8) mottles, reddish yellow (5YR 6/8) dry; massive; hard, firm, slightly sticky and plastic; few fine, medium and coarse roots; many mica chips and a few pebble-size soft sandstone fragments; strongly acid (pH 5.0).
TYPE LOCATION: Lewis County, Washington; about 9 miles east of Centralia, 100 feet north of road, 900 feet north and 500 feet west of the southeast corner of sec. 26, T. 15 N., R. 1 W.
RANGE IN CHARACTERISTICS: Average annual soil temperature at a depth of 20 inches ranges from 49 to 53 F. The umbric epipedon is 10 to 20 inches thick. These soils are usually moist but they are dry in all parts between the depths of 4 to 12 inches for 45 to 60 consecutive days following the summer solstice. The particle-size control section is 27 to 35 percent clay, and more than 15 percent coarser than very fine sand. The argillic horizon is more than 22 inches thick. Hue is 10YR or 7.5YR.
The Ac horizon has value of 2 or 3 moist, and 4 or 5 dry and chroma of 2 or 3 moist and dry. It is loam or silt loam. It is slightly acid to very strongly acid. Shot-like aggregates (2-5 mm in diameter) range from 5 to 20 percent.
The upper part of the Bt horizon has value of 4 or 5 moist, 5 or 6 dry and chroma of 3 or 4 moist, and 4 through 6 dry. It is silty clay loam or clay loam. This horizon is moderately acid to very strongly acid.
The lower part of the Bt horizon has value of 4 or 5 moist, 5 or 6 dry and chroma of 2 through 4 moist or dry. It is silty clay loam, clay loam, or loam. Mica chips and sand grains are visible in most pedons. Mottles have hue of 10YR or 7.5YR, value of 4 or 5 moist and dry, and chroma of 4 through 6 moist and dry. This horizon is strongly acid or very strongly acid. Some pedons are not mottled.
The BC horizon has value of 4 or 5 moist, 5 or 7 dry, and chroma of 2 to 8 moist and dry. It is clay loam, silty clay loam, or loam. Mica chips and sand grains are visible in most pedons. It has 0 to 35 percent soft pebble-size sandstone fragments. This horizon is strongly acid or very strongly acid. Mottles have a hue of 10YR through 5YR, value of 4 through 6 moist and dry, and chroma of 4 through 8 moist and dry. Some pedons are not mottled.
COMPETING SERIES: This is the Buckpeak series. Buckpeak soils average 35 to 60 percent soft sandstone fragments in the argillic horizon.
GEOGRAPHIC SETTING: Centralia soils are on uplands and foothills at elevations of 200 to 1,600 feet. Slope is 0 to 65 percent. These soils formed in residuum and colluvium weathered from micaceous marine sandstone. The climate is marine and characterized by cool, dry summers and mild, wet winters. The average annual precipitation is 40 to 70 inches. The average January temperature is 38 degrees F, the average July temperature is 65 degrees F, and the average annual temperature is 47 to 53 degrees F. The growing season (28 degrees F) is 175 to 240 days. The frost-free season is 150 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS These are the Baumgard, Galvin, Lacamas, Melbourne, Olequa, Olympic, Prather, Salkum, and Vader soils and the competing Buckpeak soils. Baumgard soils lack an argillic horizon. Galvin soils are fine-silty and mottled in the argillic horizon. Lacamas, Melbourne, Olympic, Prather, and Salkum soils have a fine textured argillic horizon. In addition, Lacamas soils have an aquic moisture regime. Melbourne and Prather have base saturation (by sum) more than 35 percent at 125 cm below the top of the argillic horizon. Vader soils have a cambic horizon and are coarse-loamy.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, wildlife habitat, and watershed. Some areas are used for cropland or as homesites. Overstory vegetation is Douglas-fir, western hemlock, western redcedar, red alder,bigleaf maple, and bitter cherry. Ground vegetation is salal, Oregon-grape, western swordfern, western brackenfern, trailing blackberry, red huckleberry, Pacific trillium, and vine maple.
DISTRIBUTION AND EXTENT: Southwestern Washington. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lewis County, Washington, 1976.
REMARKS: Characterization data are available on this soil, number S84WA-015-005. Diagnostic horizons and features recognized in this pedon are a umbric epipedon from the mineral surface to 17 inches and an argillic horizon from 17 to 49 inches. Base saturation (by sum) is less than 35 percent 125 cm below the top of the argillic horizon. This series was previously classified as fine-loamy, mixed, mesic Xeric Haplohumults. Classification change based on National Soil Taxonomy Handbook, Issue No. 12, re-establishing Palehumults.