LOCATION SIFTON WA+OREstablished Series
TAXONOMIC CLASS: Medial over sandy or sandy-skeletal, mixed,
mesic Typic Melanoxerands
TYPICAL PEDON: Sifton gravelly loam pasture. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 5 inches; black (l0YR 2/l) gravelly loam, dark grayish brown (l0YR 4/2) dry; weak fine granular structure; soft, very friable, slightly sticky, nonplastic; weakly smeary; many fine roots; 20 percent pebbles; NaF pH l0.5; very strongly acid (pH 5.0); abrupt smooth boundary. (4 to 6 inches thick)
All--5 to l0 inches; black (l0YR 2/l) gravelly loam, dark grayish brown (l0YR 4/2) dry; weak fine subangular blocky structure; soft, friable, slightly sticky, nonplastic; weakly smeary, many fine roots; many very fine pores; 20 percent pebbles; NaF pH ll.0; strongly acid (pH 5.4) clear smooth boundary. (4 to 6 inches thick)
Al2--l0 to l6 inches; very dark brown (l0YR 2/2) gravelly loam, dark grayish brown (l0YR 4/2) dry; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; weakly smeary; common fine roots; 25 percent pebbles, NaF pH ll.5; common very fine pores; medium acid (pH 6.0); clear wavy boundary. (4 to 7 inches thick)
2Cl--l6 to 24 inches; dark brown (l0YR 3/3) very gravelly loamy coarse sand; brown (l0YR 4/3) dry; massive; soft, very friable, nonsticky, nonplastic; few fine roots; 50 percent pebbles; NaF pH l0.0; many very fine interstitial pores; slightly acid (pH 6.2); clear wavy boundary. (7 to l0 inches thick)
2C2--24 to 60 inches; very dark grayish brown (l0YR 3/2) extremely gravelly coarse sand, dark grayish brown (l0YR 4/2) dry; single grained; loose; few very fine roots; 55 percent pebbles, NaF pH F 9.0; slightly acid (pH 6.5).
TYPE LOCATION: Clark County, Washington; 450 feet south NE 86th St. and 300 feet west of 94th Avenue, in NW, SW, or sec. 4, T. 2 N., R. 2 E. very
RANGE IN CHARACTERISTICS: Thickness of solum and depth to contrasting materials range from l4 to 28 inches. The umbric epipedon is l4 to 24 inches thick. These soils are usually moist but are dry in all parts between depths of 8 and 24 inches for 60 to 75 consecutive days following summer solstice. Mean annual soil temperature ranges from 48 to 55 degrees F. The control section contains l5 to 35 percent coarse fragments in the upper part and 50 to 75 percent coarse fragments in the lower part. The soils have l0YR or 7.5YR hue.
The Al horizon has value of 2 moist and 2 or 3 dry, and chroma of l or 2. Below l0 inches it is gravelly silt loam or gravelly loam. This horizon has weak granular or subangular blocky structure. It is very strongly acid to medium acid.
The 2C horizon has value of 3 or 4 moist and 4 through 6 dry, and chroma of 2 through 4. It is very gravelly loamy coarse sand, very gravelly coarse sand, very gravelly sand, extremely gravelly sand or extremely gravelly coarse sand. This horizon is very strongly acid to slightly acid. Some pedons, with solums approaching 28 inches thick, contain a B horizon. The B horizon has value of 3 or 4 moist and 4 or 5 dry, and chroma of 3 or 4. It is loam or sandy loam and is gravelly.
COMPETING SERIES: These are the similar Carstairs and Spanaway series. These soils are sandy-skeletal.
GEOGRAPHIC SETTING: These soils are on terraces at elevations of 30 to 400 feet with slopes of 0 to 8 percent. They formed in gravelly alluvium containing volcanic ash in the upper part. These soils occur in a humid marine climate with relatively cool dry summers and mild moist winters. The average annual precipitation is 40 to 70 inches. Average January temperature is 37 degrees F.; average July temperature is 64 degrees F.; mean annual temperature is 50 degrees F.; and average growing season is l70 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lauren and Winston soils. Lauren and Winston soils lack umbric epipedons.
DRAINAGE AND PERMEABILITY: Well drained; very slow runoff; very rapid permeability.
USE AND VEGETATION: Used mainly for cropland and pasture. Hay and small grains are common crops where not irrigated. Where irrigated, caneberries, tree fruits, and alfalfa are grown. Native vegetation is grasses and scattered Douglas-fir. Scotchbroom is an invader in cleared areas left idle.
DISTRIBUTION AND EXTENT: Southwestern Washington and northwestern Oregon. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Reconnaissance Soil Survey of Southwest Washington, l9ll. Remarks: In the upper part of the particle-size control section these soils have a NaF pH of more than 9.4 and are assumed to have a ratio of l5 bar water content to clay of more than l.0. The organic carbon is greater than 2 percent. The bulk density of the fine earth fraction is assumed to be between 0.85 and l.0.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy.
In the upper part of the particle-size control section these soils have a NaF pH of more than 9.4 and are assumed to have a ratio of 15 bar water content to clay of more than 1.0. The organic carbon is greater than 2 percent. The bulk density of the fine earth fraction is assumed to be between 0.85 and 1.0.