LOCATION SNOW WA+OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Snow silt loam- cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 8 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many roots; neutral (pH 7.0); abrupt smooth boundary.
A1--8 to 12 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; common very fine and fine tubular pores; neutral (pH 7.0); abrupt smooth boundary.
A2--12 to 21 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; massive or weak medium prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; common very fine tubular pores; neutral (pH 7.2); clear wavy boundary. (Combined thickness of the A horizon is 18 to 40 inches)
Bw--21 to 36 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; few fine and common very fine tubular pores; neutral (pH 7.2); clear smooth boundary. (10 to 20 inches thick)
C1--36 to 44 inches; brown (10YR 5/3) silt loam, brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common roots; few fine and common very fine tubular pores; neutral (pH 7.2); clear wavy boundary. (6 to 12 inches thick)
C2--44 to 60 inches; pale brown (10YR 6/3) silt loam, dark yellowish brown (10YR 4/4) moist; weak medium prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; few roots; many fine and medium tubular pores; discontinuous gray coatings on peds; neutral (pH 6.8).
TYPE LOCATION: Spokane County, Washington; 40 feet north of Latah Waverly Road; SW1/4 SW1/4 NW1/4 section 3, T.21N., R.44E., WM.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry in all parts between depths of 4 and 12 inches for 60 to 80 consecutive days in the summer and fall. The mollic epipedon ranges from 30 to 48 inches thick and may include part of the Bw horizon. Average annual soil temperature ranges from 48 to 52 degrees F.
The Ap and A horizons have value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 dry or moist. Soil reaction is neutral or slightly alkaline.
The Bw horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 or 3 dry or moist. It is 18 to 22 percent clay. Soil reaction is neutral to moderately alkaline.
The C horizon has hue of 10YR or 2.5Y, value of 3 or 4 moist, 5 or 6 dry and chroma of 2 to 4 moist and dry. It is silt loam or loam and 18 to 27 percent clay. It has 0 to 10 percent gravel. Soil reaction is neutral to moderately alkaline.
COMPETING SERIES: These are the Caldwell, Harana, Jett, Keigley, Loupence, Red Rock, and Rustico series. Caldwell soils have distinct redox concentrations and are somewhat poorly drained. Harana soils are moderately alkaline, calcareous, and average 27 to 35 percent clay within the particle-size control section and are well drained. Jett soils are calcareous in all or part of the A horizon and within the upper part of the particle-size control section. Keigley soils are calcareous and have 15 to 30 percent calcium carbonate equivalent throughout. Loupence soils have an aridic soil moisture regime. Red Rock soils have calcareous C horizons above depth of 40 inches. Rustico soils have redox concentrations between 50 and 60 inches, are calcareous throughout, and have an aridic soil moisture regime bordering xeric.
GEOGRAPHIC SETTING: Snow soils are on gently sloping to moderately steep terraces and terrace side slopes at elevations of 1,800 to 3,400 feet. These soils formed in loess and alluvium from loess. Slopes are 0 to 30 percent. The summers are hot and dry and winters are cool and moist. The average annual precipitation is typically 18 to 23 inches but ranges to 13 inches in northeastern Oregon. The average annual temperature is 45 to 50 degrees F.; the average January temperature is 28 degrees F.; the average July temperature is 68 degrees F. Frost-free season is 100 to 125 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Athena, Garfield, Latah, Palouse, and Thatuna soils. Athena soils are on uplands and have a regular decrease of organic matter with increasing depth. Garfield soils are on uplands and Latah soils are on bottomlands and both soils have fine textured control sections. Palouse soils are on uplands and have base saturation of less than 75 percent in all parts of the upper 30 inches. Thatuna soils are on uplands and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: Used for production of small grains, lentils, peas, alfalfa, and of grasses for hay and pasture. Native vegetation is Idaho fescue, bluebunch wheatgrass, prairie junegrass, big bluegrass.
DISTRIBUTION AND EXTENT: Eastern Washington and Oregon, and western Idaho; MLRA 9. This soil is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: South Palouse River Project, Whitman County, Washington and Latah County, Idaho, 1939.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to 21 inches (the Ap, A1, and A2 horizons).
Cambic horizon - from 21 to 36 inches