LOCATION SCHUMACHER WA+IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Ultic Argixerolls
TYPICAL PEDON: Schumacher silt loam, cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many fine roots; neutral (pH 6.8); abrupt smooth boundary. (6 to 10 inches thick)
A--6 to 12 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; many roots; many fine pores; neutral (pH 6.8); gradual wavy boundary. (0 to 10 inches thick)
AB--12 to 19 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2); moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common roots; many fine pores; 5 percent pebble size quartzite; neutral (pH 6.8); abrupt wavy boundary. (4 to 10 inches thick)
Bt1--19 to 31 inches; dark brown (7.5YR 4/4) silty clay loam, dark brown (7.5YR 3/4) moist; strong fine and medium angular blocky structure; very hard, very firm, sticky, plastic; few roots; few medium pores; thick continuous clay films on peds; 15 percent pebble size quartzite; neutral (pH 6.8); clear wavy boundary. (6 to 10 inches thick)
Bt2--31 to 37 inches; brown (7.5YR 5/4) silty clay loam, dark brown (7.5YR 4/4) moist; strong fine and medium blocky structure; very hard, very firm, sticky, plastic; few fine roots; few medium pores; thick continuous clay films on peds; 10 percent pebble size quartzite; neutral (pH 6.6); clear wavy boundary. (8 to 10 inches thick)
Bt3--37 to 43 inches; brown (7.5YR 5/4) silty clay loam, dark brown (7.5YR 4/4); moist; moderate fine subangular blocky structure; very hard, very firm, sticky, plastic; very few fine roots; many very fine pores; thin continuous clay films on peds; 12 percent pebble size quartzite; neutral (pH 6.6).
R--43 inches; metasediments.
TYPE LOCATION: Whitman County, Washington; 1,500 feet south and 1,800 feet west of the NW corner of section 19, T.19N., R.44E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 47 to 52 degrees F. Thickness of the solum ranges from 30 to more than 40 inches. Thickness of the mollic epipedon ranges from 10 to 20 inches. These soils are usually moist but are dry in all parts between depths of 4 and 12 inches for 45 to 60 consecutive days in summer and autumn. The particle-size control section is 25 to 35 percent clay and 5 to 30 percent rock fragments.
The A horizon have value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 or 2 dry or moist. It has weak to moderate structure.
The Bt1 and Bt2 horizons have hue of 7.5YR or 10YR, value of 4 through 6 dry, 3 or 4 moist, and chroma of 3 or 4 dry or moist. They are silty clay loam, clay loam, or heavy silt loam and is cobbly, stony or gravelly in some pedons.
The Bt3 horizon has value of 5 through 7 dry, 3 through 5 moist, and chroma of 3 or 4 dry or moist. It is heavy silt loam, clay loam, or silty clay loam and is stony, cobbly, or gravelly in some pedons. Ped surfaces in the B2 horizons have thin continuous to thick continuous clay films. Some peds have graying or striping and some contain few manganese shot or coatings.
COMPETING SERIES: These are the Brownlee, Dragoon, Felton, Garcia, Georgecreek, Glenrose, Goldendale, Lompico, Meland, Morical, Meystre, Rehfield, Van Horn, and Yaxon series. Brownlee soils are dry for more than 60 consecutive days and a coarse sandy clay loam or coarse sandy loam in the lower part of the particle-size control section. Felton soils have a mean annual soil temperature of about 56 degrees F and are dry more than 60 consecutive days. Dragoon, Lompico, and Morical soils are 20 to 40 inches deep to a paralithic contact. Garcia, Meland and Rehfield soils are 20 to 40 inches deep to a lithic contact. Glenrose soils are 18 to 25 percent clay in the particle-size control section. Georgecreek, Goldendale, Meystre, and Van Horn soils are dry more than 60 consecutive days. Yaxon soils are dry for more than 60 consecutive days and lack hard rock fragments in the particle-size control section.
GEOGRAPHIC SETTING: These soils occur at elevations of 2,200 to 4,000 feet. Slopes are 0 to 65 percent. The soils formed in loess and residual material from quartzite, sandstone or intrusive igneous rock. The mean January temperature is about 27 degrees F.; the mean July temperature is about 67 degrees F.; and the mean annual temperature is about 47 degrees F. The frost free season is 120 to 140 days and the average annual precipitation is 18 to 24 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Garfield, Larkin, Naff, Palouse, Speigle, Tekoa, Tilma, and Thatuna soils. Garfield soils have an ochric epipedon. Larkin, Naff, Palouse and Thatuna soils are fine-silty. Speigle soils are loamy-skeletal and have a cambic horizon. Tekoa soils are 20 to 40 inches deep to bedrock. Tilma soils are fine.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: Native vegetation is Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass, common snowberry, arrowleaf balsamroot, prairie junegrass, and some scattered ponderosa pine. Cultivated area are used for production of small grains, peas, alfalfa and grass.
DISTRIBUTION AND EXTENT: Eastern Washington and northern Idaho. Schumacher soils are of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: North Palouse Conservation District, Whitman County, Washington, 1942.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 19 inches, an argillic horizon from 19 to 43 inches, and a lithic contact at 43 inches.