LOCATION ZILLAH WAEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Fluvaquentic Endoaquolls
TYPICAL PEDON: Zillah silt loam, range. (Colors are for dry soil unless otherwise stated.)
A1--0 to 2 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to weak fine and medium granular; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; neutral (pH 6.8); abrupt smooth boundary. (0 to 7 inches thick)
A2--2 to 19 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist massive; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; common fine tubular pores; many medium distinct brown (7.5YR 4/4) moist redox concentrations; neutral (pH 6.8); gradual wavy boundary. (8 to 18 inches thick)
C1--19 to 31 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist massive; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; common fine tubular pores; many medium distinct reddish brown (5YR 4/4) moist redox concentrations; neutral (pH 6.8). (8 to 16 inches thick)
C2--31 to 51 inches; gray (10YR 6/1) silt loam,; dark gray (10YR 4/1) moist; very dark grayish brown (10YR 3/2) moist and rubbed; massive; soft, very friable, nonsticky and nonplastic; common fine roots; common fine tubular pores; several 1/2 to 2 inch thick lenses of loamy sand; many medium distinct brown (7.5YR 4/4) moist redox concentrations; neutral (pH 6.8); abrupt wavy boundary. (16 to 30 inches thick)
2C3--51 to 60 inches; gray (10YR 6/1) loamy sand; dark gray (10YR 4/1) moist; very dark grayish brown (10YR 3/2) moist and rubbed; massive; loose; few fine roots; many coarse prominent dusky red (2.5YR 3/2) and dark brown (7.5YR 3/4) moist redox concentrations; neutral (pH 6.7).
TYPE LOCATION: Yakima County, Washington; 1,500 feet west of Winnier Road and 4,000 feet north of Highway 22; SE1/4 SW1/4 NE1/4 section 20, T.9N., R.22E., WM.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 48 to 55 degrees F. These soils are saturated with water within 12 inches of the surface for more than 90 days (cumulative) during the year if not artificially drained. The mollic epipedon is 12 to 24 inches thick. Depth to the 2C horizon exceeds 40 inches.
The A horizon, and AB horizon when present, has value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 or 2 dry or moist. Texture is silt loam or sandy loam. Distinct or prominent redox features are in the lower part. Reaction is slightly acid to slightly alkaline.
Some pedons have a Bg horizon with value of 4 or 5 dry, 2 or 3 moist and chroma of 2 or 3 dry or moist. Texture is silt loam or very fine sandy loam. It has distinct or prominent redox features.
The C horizon has hue of 10YR, 2.5Y or is neutral, value of 5 or 6 dry and chroma of 1 to 3 dry or moist.Texture is silt loam, sandy loam or very fine sandy loam and has thin lenses of loamy sand in the lower part. It has distinct or prominent redox features. Reaction is neutral to moderately alkaline.
The 2C horizon has the same color range as the C horizon. Texture is loamy sand, gravelly loamy sand, very gravelly loamy sand or extremely gravelly coarse sand.
COMPETING SERIES: This is the Fontanelle series and the Esquatzel, Kittitas, Onyx, and Pasco series in other families. Fontanelle soils have a buried A horizon between 24 and 60 inches. Esquatzel soils lack an aquic moisture regime and mottles. Kittitas soils are fine, silty. Onyx soils lack an aquic moisture regime and mottles and have a dry value of 5 or less throughout. Pasco soils have a mollic epipedon more than 24 inches thick and are calcareous in all parts of the calcareous class control section.
GEOGRAPHIC SETTING: Zillah soils occur on flood plains in stream valleys. Elevations are 600 to 1,800 feet. Slopes are 0 to 5 percent. The soils formed in recent alluvium. The mean annual precipitation is 6 to 12 inches. The mean annual temperature of 47 to 51 degrees F.. The frost-free season of 130 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Esquqtzel and Onyx soils and the Weirman soils. Weirman soils are sandy-skeletal.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow runoff or ponded; moderate permeability. Zillah soils are subject to frequent or occasional flooding for long periods from January to March unless protected. This soil has an irrigation induced water table with its uppermost limit occurring at some time between April and November.
USE AND VEGETATION: These soils are used for pasture, hay, and wildlife habitat. Some areas have ben drained and are used for irrigated crops. Native vegetation is willows, cottonwood, sedges, and annuals.
DISTRIBUTION AND EXTENT: South central Washington.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yakima Indian Reservation, Irrigated Portion, Washington, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon the zone from 0 to 19 inches (A1 and A2 horizons)
Particle-size control section the zone from 10 to 40 inches
Aquic feature the zone beginning at 2 inches having chroma of 2 or less and redox concentations.