LOCATION MART WAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Mart silt loam, pasture. (Colors are for moist soil unless otherwise noted.)
A1--0 to 4 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots, many fine irregular and tubular pores; strongly acid (pH 5.3); abrupt smooth boundary.
A2--4 to 11 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate medium subangular blocky structure parting to moderate fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine and many fine roots; many fine irregular and tubular pores; strongly acid (pH 5.5); clear smooth boundary. (Combined thickness of the A horizon is 8 to 14 inches)
BAt--11 to 20 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few patchy faint very dark grayish brown (10YR 3/2) clay films on faces of peds; many very fine and common fine roots; few fine irregular and tubular pores; moderately acid (pH 5.8); clear smooth boundary. (8 to 11 inches thick)
Bt1--20 to 26 inches; dark brown (10YR 3/3) silty clay loam, brown (10YR 5/3) dry; strong medium subangular blocky structure; hard, firm, sticky and plastic; many discontinuous distinct dark brown (10YR 3/3) clay films on faces of peds; many very fine and common fine roots; few fine irregular and tubular pores; moderately acid (pH 5.8); clear smooth boundary.
Bt2--26 to 40 inches; dark yellowish brown (10YR 4/4) silty clay lay, brown (10YR 5/3) dry; moderate medium prismatic structure parting to strong medium subangular blocky; hard, firm, sticky and plastic; brown to dark brown (7.5YR 4/4) clay films on faces of peds; few very fine and few fine roots; few fine irregular and tubular pores; 10 percent pebbles from saprolite; moderately acid (pH 5.8); clear smooth boundary. (Combined thickness of the Bt horizon is 17 to 24 inches)
BCt1--40 to 58 inches; dark yellowish brown (10YR 4/4) silty clay loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure; hard, firm, sticky and plastic; many discontinuous distinct brown to dark brown (7.5YR 4/4) clay films on faces of peds; moderately acid (pH 5.8); abrupt smooth boundary. (15 to 22 inches thick)
BCt2--58 to 72 inches; very dark grayish brown (10YR 3/1) dark grayish brown (10YR 4/2) and brown to dark brown (7.5YR 4/4); silt loam; yellowish brown (10YR 5/4) dry; moderate coarse subangular blocky structure; hard, firm, sticky and plastic; many discontinuous distinct brown to dark brown (7.5YR 4/4) clay films on faces of peds; moderately acid (pH 6.0).
TYPE LOCATION: Cowlitz County, Washington; Cowlitz County, Washington; about 5 miles north of Woodland, 1,900 feet west, 200 feet north of the southeast corner section 26, T. 6 N., R. 1 W.
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in the moisture control section for 45 to 60 consecutive days following the summer solstice. Average annual soil temperature ranges from 48 to 52 degrees F. The mollic epipedon is 20 to 30 inches thick and includes part of the argillic horizon. Soil reaction is moderately acid or strongly acid.
The A horizon has value of 2 to 4 when moist and 3 to 5 when dry, and chroma of 2 through 4 when moist or dry. It is silt loam or silty clay loam.
The Bt horizon has hue of 10YR or 7.5YR, value of 3 or 4 when moist and 4 or 5 when dry, and chroma of 2 or 3 when moist or dry. It is silty clay loam or light silty clay.
COMPETING SERIES: These are the Coburg, Darby, Dixonville, Malabon, Redbell, and Silverton series. Coburg and Malabon soils are slightly acid or neutral in the argillic horizon and have a mean annual soil temperature of 52 to 55 degrees F. Darby soils have a mollic epipedon 30 to 60 inches thick and a mean annual soil temperature of 52 to 57 degrees F. Dixonville soils are 20 to 40 inches deep to a paralithic contact. Redbell soils have mottles with a chroma of 2 or less within 30 inches of the soil surface and are dry for 60 to 80 consecutive days. Silverton soils are 20 to 40 inches deep to a lithic contact.
GEOGRAPHIC SETTING: Mart soils are on nearly level to very steep dissected convex mountain slopes, hillslopes and ridgetops at elevations of 500 to 1,800 feet. They developed in material weathered from andesite or volcanic breccia. The climate is characterized by warm, dry summers and cool, wet winters. The average January temperature is about 38 degrees F, the average July temperature is 64 degrees F. The average annual temperature is about 50 degrees F. The average growing season (28 degrees F.) is 220 to 240 days. The average annual precipitation is 40 to 75 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gee, Hazeldell, Kalama, Olympic, and Rosevalley soils. Gee and Rose Valley soils have E horizons that tongue into the B horizons. Hazeldell soils have less than 35 percent clay in the particle-size control section. Kalama soils are gravelly or very gravelly. Olympic soils have a base saturation of less than 35 percent at a depth of 1.25 meters below the upper boundary of the argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: Used for timber, small grains, pasture, and hay production. The principal native plants are Douglas-fir, red alder, grand fir, western redcedar, bigleaf maple, willow, bitter cherry, creambush oceanspray, cascara buckthorn, western hazel, salal, salmonberry, western brackenfern, and vine maple.
DISTRIBUTION AND EXTENT: Southwestern Washington. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cowlitz County, Washington, 1971.
REMARKS: Characterization data are available on this pedon--NSSL numbers 845088-5094. Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 26 inches and an argillic horizon from 20 to 58 inches.