LOCATION REARDAN WAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Calcic Argixerolls
TYPICAL PEDON: Reardan silt loam, cultivated. (Colors are for moist soils unless otherwise noted.)
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak fine and medium granular structure; slightly hard, friable, slightly sticky, slightly plastic; many roots; neutral (pH 6.6); clear smooth boundary. (7 to 10 inches thick)
A--9 to 16 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium and thick platy structure; slightly hard, friable, slightly sticky, slightly plastic; many roots; common very fine and fine pores; neutral (pH 6.8); clear wavy boundary. (5 to 10 inches thick)
B/E--16 to 20 inches; pale brown (10YR 6/3) heavy silt loam, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure parting to weak fine and medium subangular blocks; hard, friable, sticky, plastic; common roots; many very fine pores; light gray (10YR 7/1) bleached silt grains on faces of prisms; neutral (pH 7.0); clear wavy boundary. (2 to 5 inches thick)
Bt--20 to 33 inches; pale brown (10YR 6/3) light silty clay, dark yellowish brown (10YR 4/4) moist; moderate coarse prismatic structure parting to strong medium angular blocks; very hard, extremely firm, very sticky, very plastic; few roots confined to cleavage planes; many very fine pores; thin continuous clay films on faces of peds and in pores with common clean mineral grains on surfaces; neutral (pH 7.3); gradual wavy boundary. (10 to 14 inches thick)
Btk--33 to 60 inches; very pale brown (10YR 7/4) silt loam, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic structure; hard, friable, sticky, plastic; few roots; many very fine pores; few thin patchy clay films; slightly effervescent, most pores coated with lime; moderately alkaline (pH 8.3).
TYPE LOCATION: Spokane County, Washington; 3,200 feet north and 50 feet west of junction of Coulee Hite and Sunset Highway roads in SE1/4 SE1/4 NE1/4 section 20, T.25N., R.40E.
RANGE IN CHARACTERISTICS: Solum thickness and depth to bedrock are 40 to more than 60 inches. Depth to lime is 24 to 35 inches. The mollic epipedon is 10 to 20 inches thick. These soils are usually moist, but are dry in all parts between depths of 4 and 12 inches for 60 to 90 consecutive days during summer and autumn. The mean annual soil temperature is 47 to 52 degrees F.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 to 3. It is loam, silt loam, or silty clay loam.
The Bt horizon has hue of 10YR, 7.5YR or 5YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 or 4. It is heavy silty clay loam, light silty clay, or light clay and has 35 or 45 percent clay. This horizon is neutral or mildly alkaline.
The Btk horizon is similar to the Bt horizon in color and texture and is mildly to moderately alkaline.
COMPETING SERIES: These are the Broadax, Flowell, Gemson and Oxford series in other families. Broadax soils have 18 to 35 percent clay. Flowell, Gemson and Oxford soils have montmorillonitic mineralogy.
GEOGRAPHIC SETTING: These soils are on nearly level to strongly sloping uplands at elevations of 1,500 to 2,800 feet. The soils formed in residuum from basalt with a loess mantle. These soils occur in a climate with warm, dry summers and cool, moist winters. The average January temperature is 25 degrees F.; the average July temperature is 66 degrees F.; and the mean annual temperature is 47 degrees F. The annual precipitation is 15 to 18 inches. The average frost free season is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dearyton, Dragoon and Green Bluff soils. All of these soils lack lime within the control section.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; slow permeability.
USE AND VEGETATION: Mostly used for cropland and some is used for woodland and grazing. Small grains and alfalfa, clover and grass hay are common crops. Native vegetation is ponderosa pine, Idaho fescue, bluebunch wheatgrasses, balsamroot, and common snowberry.
DISTRIBUTION AND EXTENT: Eastern Washington. Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Spokane County, Washington, 1964.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 16 inches, and an argillic horizon from 16 to 60 inches. The layer from 16 to 20 inches (B/E) has bleached coatings on faces of peds and the layer from 33 to 60 inches (Btk) has secondary lime in pores.