LOCATION ANNUM WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Ultic Argixerolls
TYPICAL PEDON: Annum silt loam - on a 12 percent northwest-facing slope at 2,720 feet elevation under native range vegetation. (Colors are for dry soil unless otherwise stated.)
A1--0 to 8 inches; dark grayish brown (10YR 4/2) silt loam black (10YR 2/1) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine and fine roots; neutral (pH 6.8); gradual smooth boundary (5 to 10 inches thick)
A2--8 to 12 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak moderate and coarse subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine and fine roots; neutral (pH 6.8); clear smooth boundary. (4 to 12 inches thick)
BA--12 to 18 inches; brown (10YR 5/3) heavy silt loam, dark brown (10YR 4/3) moist; weak fine and medium subangular blocky structure, slightly hard, friable, sticky, plastic; few very fine roots; very few thin clay film lining pores; neutral (pH 7.0); abrupt smooth boundary. (0 to 9 inches thick)
Bt1--18 to 24 inches; yellowish brown (10YR 5/4) heavy silt loam, brown (10YR 4/3) moist; weak fine subangular blocky structure parting to very fine subangular blocky; hard, friable, sticky, plastic; few very fine roots; few thin clay films on ped faces; neutral (pH 7.0); clear smooth boundary. (0 to 12 inches thick)
2Bt2--24 to 46 inches; strong brown (7.5YR 5/6) clay loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; hard, firm, sticky, plastic; few very fine roots; common thin clay films lining pores and on ped faces; mildly alkaline (pH 7.4); clear smooth boundary. (8 to 24 inches thick)
2Bk--46 to 53 inches; light yellowish brown (10YR 6/4) gravelly sandy loam, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; few very fine roots; 20 percent fine granitic pebbles; moderately alkaline (pH 8.0); violently effervescent; few soft masses and filaments of lime; clear smooth boundary. (0 to 9 inches thick)
2Cr--53 inches; highly weathered granodiorite which breaks to gravelly loamy coarse sand.
TYPE LOCATION: Colville Indian Reservation; Ferry County, Washington; about 7 miles northeast of the town of Coulee Dam; 1,850 feet east, 300 feet south of the northwest corner of sec. 30, T. 29 N., R. 32 E., W.M.
RANGE IN CHARACTERISTICS: Mean annual soil temperature at 20 inches depth ranges from 49 to 52 degrees F. These soils are dry in the moisture control section for 90 to 105 days following the summer solstice. Depth to a paralithic contact ranges from 40 to 60 inches. The control section averages 0 to 10 percent coarse fragments and 18 to 35 percent clay. The mollic epipedon is 10 to 20 inches thick.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 through 3 dry or moist. It has weak or moderate structure. It is 0 to 5 percent pebbles.
The Bt horizon has value of 5 or 6 dry, and chroma of 3 or 4 dry or moist. It is silt loam or loam with 0 to 5 percent pebbles.
The 2Bt horizon has hue of 7.5YR or 10YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 through 6 moist or dry. Texture is loam, clay loam, or sandy clay loam. Structure is moderate or strong subangular blocky. Organic carbon is less than 1 percent. It is 0 to 10 percent pebbles. It is neutral or mildly alkaline.
The 2Bk horizon has value of 6 or 7 dry, 4 to 6 moist, and chroma of 3 or 4 dry or moist. It is gravelly loam or loam or sandy loam and is gravelly in some pedons. Reaction is mildly alkaline or moderately alkaline. Some pedons lack a 2Bk horizon and have a 2BC horizon.
COMPETING SERIES: These are the Brownlee, Chirpchatter, Dragoon, Felton, Garcia (T), Georgecreek (T), Glenrose, Goldendale (T), Lompico, Meland, Meystre, Rehfield, Schumacher, Shilly, Updegraff, and Van Horn series. Brownlee, Meystre, Schumacher, and Van Horn soils are dry for less than 80 days in the moisture control section. Chirpchatter soils are dry for more than 105 consecutive days. Dragoon and Lompico soils are 20 to 40 inches deep to a paralithic contact. Garcia, Meland, Rehfield, and Shilly soils are 20 to 40 inches deep to a lithic contact. Felton soils have a mean annual soil temperature of 56 degrees F. Georgecreek, Goldendale, and Glenrose soils are dry for 75 to 90 consecutive days in the moisture control section. Sanhedrin soils have a mean annual soil temperature of 52 to 54 degrees F, and 15 to 35 percent rock fragments in the particle-size control section. Updegraff soils are 5 to 30 percent rock fragments in the particle-size control section and are dry for more than 105 consecutive days.
GEOGRAPHIC SETTING: Annum soils are on broad summits, shoulders, and toeslopes of hills at elevations of 2,400 to 3,200 feet. Slopes are 8 to 25 percent. These soils formed in residuum from granitic rocks with a mantle of loess. Annum soils are in a climate with warm, dry summers and cold, moist winters. The mean January temperature is about 25 degrees F, mean July temperature is about 71 degrees F, mean annual air temperature is about 48 degrees F. The average annual precipitation ranges from 12 to 15 inches. The frost-free season ranges from 110 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Broadax, Ginnis, Morical, and Tyee soils. Broadax soils are fine-silty. Ginnis and Morical soils are 20 to 40 inches deep to a paralithic contact. Tyee soils are 10 to 20 inches deep to a paralithic contact.
DRAINAGE AND PERMEABILITY: Well drained, medium to very rapid runoff, moderate permeability.
USE AND VEGETATION: Small grain in a summer fallow system, range and hay. Vegetation is bluebunch wheatgrass, Idaho fescue, arrowleaf balsamroot, Wyeth eriogonium, three-tip sagebrush, and silky lupine.
DISTRIBUTION AND EXTENT: Northcentral Washington. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Colville Indian Reservation, Ferry County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 12 inches and an argillic horizon from 18 to 46 inches.