LOCATION TOUCHET WAEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Touchet silt loam - cultivated. (Colors are for dry soil unless otherwise stated).
Ap--0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, slightly stocky and slightly plastic; many roots, fine pores numerous within peds; mildly alkaline (pH 7.5); abrupt smooth boundary. (6 to 10 inches thick)
A1--8 to 19 inches; grayish brown (10 YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium platy; slightly hard, friable; slightly sticky and slightly plastic; many roots; abundant fine pores; mildly alkaline (pH 7.5); clear wavy boundary. (5 to 12 inches thick)
A2--19 to 39 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) when moist; weak thin platy; slightly hard, friable, slightly sticky and plastic; many roots; numerous medium pores; mildly alkaline (pH 7.4); gradual wavy boundary. (10 to 20 inches thick)
A3--39 to 47 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) with dark reddish brown (5YR 3/4) mottles moist; massive; slightly hard, friable; many roots; numerous fine pores; neutral (pH 7.2); clear wavy boundary.
A4--47 to 60 inches; gray (10YR 5/1) silt loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, friable; few roots; neutral (pH 7.2); abrupt boundary.
TYPE LOCATION: South of Whitman Station near Walla Walla River in Walla Walla County, Washington in the NE1/4SE1/4, sec. 36, T. 7 N., R. 34 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 52 to 55 degrees F. These soils are usually moist, but are dry in the moisture control section for 75 to 90 consecutive days. The particle-size control section is 10 to 18 percent clay. Mottles are in the lower part of the particle-size control section.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 moist and dry. Reaction is neutral or mildly alkaline.
Some pedons have a 2C horizon below 40 inches that is very gravelly sand, very cobbly sand, or very gravelly sandy loam
COMPETING SERIES: These are the Covello, Hermiston, Mondovi, Onyx, Pedigo, and Powder series. Covello soils are moderately alkaline or strongly alkaline in the A horizon and are somewhat poorly drained. Hermiston, Mondovi, and Onyx soils lack mottles in the particle-size control section. Pedigo soils are calcareous and strongly alkaline throughout the A horizon. Powder soils are usually dry and are calcareous in the lower part of the A horizon.
GEOGRAPHIC SETTING: Touchet soils are on flood plains at elevations of 500 to 1,000 feet. They formed in recent alluvium mostly from loess. Slopes are 0 to 3 percent. These soils are in a climate with hot, dry summers and cool, moist winters. Average annual precipitation is 10 to 14 inches. The average January temperature is about 32 degrees F, the average July temperature is about 73 degrees F, and the mean annual temperature is about 52 degrees F. The average frost-free season is 150 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ahtanum, Umapine, Walla Walla, and Yakima soils and the competing Onyx soils. Ahtanum and Umapine soils are saline-alkali affected. Walla Walla soils have a mollic epipedon less than 20 inches thick, lack mottles, and have a regular decrease of organic carbon with depth. Yakima soils are coarse-loamy over sandy or sandy-skeletal.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderate permeability. These soils are subject to occasional very brief flooding in February through April and have an apparent high water table as high as 3 to 5 feet at times from January through April.
USE AND VEGETATION: Most of these soils have been cleared and are used for cropland. Wheat, barley, alfalfa hay and pasture are common crops. Native vegetation was Idaho fescue, basin wildrye, bluebunch wheatgrass, big sagebrush, and willow and black cottonwood on stream banks.
DISTRIBUTION AND EXTENT: Southeastern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Walla Walla County, Washington, 1960.
REMARKS: pH values are unavailable as of date of this draft. Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 60 inches with mottles in the lower part and an assumed irregular decrease in organic carbon with depth.