LOCATION RUDO IDInactive Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Rudo loam - forested on a 60 percent southwest aspect at 2,050 feet elevation. (Colors are for dry soil unless otherwise noted.)
A1--0 to 6 inches; brown (10YR 5/3) loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine and medium roots; many very fine and fine irregular, and common fine tubular pores; 5 percent gravel; slightly acid (pH 6.2); clear wavy boundary.
A2--6 to 14 inches; brown (10YR 5/3) loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots; many very fine and fine irregular, and common very fine and fine tubular pores; 5 percent gravel and 5 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (Combined thickness of the A horizons is 10 to 16 inches)
BA--14 to 25 inches; yellowish brown (10YR 5/4) clay loam, dark brown (10YR 3/3) moist; weak fine prismatic structure parting to moderate fine subangular blocky; hard, friable, slightly sticky and plastic; common very fine and fine roots; many very fine and fine irregular pores; common distinct clay films in pores and on faces of peds; 10 percent gravel; clay banding throughout horizon; neutral (pH 6.8); clear wavy boundary. (7 to 11 inches thick)
Bt1--25 to 32 inches; yellowish brown (10YR 5/4) clay loam, dark brown (10YR 3/3) moist; moderate fine and medium prismatic structure; hard, firm, sticky and plastic; common very fine and fine roots; many very fine and fine and common medium irregular pores and common very fine tubular pores; many distinct clay films in pores and on faces of peds; 10 percent gravel; neutral (pH 6.6); clear wavy boundary.
Bt2--32 to 41 inches; yellowish brown (10YR 5/4) gravelly clay loam, dark yellowish brown (10YR 3/4) moist; moderate fine and medium prismatic structure; hard, firm, sticky and plastic; common very fine and few fine roots; many very fine and fine irregular, and common very fine tubular pores; many prominent and distinct clay films in pores and on faces of peds; common light yellowish brown (10YR 6/4) skeletans on faces of peds; 20 percent gravel; neutral (pH 6.6); clear wavy boundary.
Bt3--41 to 56 inches; yellowish brown (10YR 5/4) very cobbly clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; common very fine and few fine roots; common very fine and fine irregular pores; many distinct and common prominent clay films in pores and on faces of peds; 20 percent gravel and 20 percent cobbles; neutral (pH 6.6); clear smooth boundary. (Combined thickness of the Bt horizons is 31 to 44 inches)
Cr--56 inches; weathered granitic schist with few very fine and fine roots in cracks.
TYPE LOCATION: Clearwater County, Idaho; about 0.75 miles northwest of Ahsahka, Idaho; about 200 feet south and 2,350 feet east of the northwest corner of section 33, T. 37 N., R 1 E. Latitude - 46 degrees, 30 minutes, 52 seconds North; Longitude - 116 degrees, 20 minutes, 14 seconds West.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 20 to 41 inches
Depth to paralithic contact - 40 to 60 inches
Rock fragment content in the particle-size control section - 5 to 40 percent; averages less then 35 percent
Clay content in the particle-size control section - averages 29 to 34 percent
Average annual soil temperature - 47 to 51 degrees F.
Base saturation - less than 75 percent in the 10 to 30 inch zone
A horizons:
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Bt horizons:
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Textures - CL, GR-CL or CBV-CL
Average clay content - 28 to 37 percent
Reaction - slightly acid or neutral
COMPETING SERIES: These are the Aptos, Buckeye(T), Campfour, Elmore, Hyprairie(T), Kiakus(T), Lauby(T), Nisene, Paragon, Roseburg(T), Swalecreek(T), and Yaxing(T) series. Aptos and Paragon soils are moderately deep to paralithic contact. Buckeye and Kiakus soils are moderately deep. Campfour soils have hues of 7.5YR, 5YR and 2.5YR. Elmore soils are deep to a lithic contact. Hyprairie soils do not have mollic colors in any part of the argillic. Lauby soils have a buried Bt horizon. Nisene soils have an average annual soil temperature of 56 to 58 degrees F. Roseburg soils have an average annual soil temperature of 52 to 56 degrees F. Swalecreek and Yaxing soils are very deep.
GEOGRAPHIC SETTING: Rudo soils are on canyon sides slopes at elevations of 1,000 to 2,200 feet. This soil formed in loess mixed with colluvium and alluvium weathered from granitic schist. The slope range is 30 to 65 percent. The average annual temperature is 45 to 50 degrees F. The average annual precipitation is 20 to 24 inches and the frost free season is 110 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ahsahka(T), Johnson and Keuterville series. Ahsahka soils are on canyon side slopes and are not pachic. Johnson soils are on canyon side slopes and have frigid soil temperature regimes. Keuterville soils are on canyon side slopes and are skeletal.
DRAINAGE AND PERMEABILITY: Well drained; very rapid runoff; moderately slow permeability.
USE AND VEGETATION: Used mainly for livestock grazing, wildlife habitat and marginal timber production. Potential native vegetation is ponderosa pine with an understory of bluebunch wheatgrass, Idaho fescue, arrowleaf balsamroot, lupine, baldhip rose and common snowberry.
DISTRIBUTION AND EXTENT: North central Idaho. Rudo soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Clearwater County, Idaho. The name is from a railroad siding.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 32 inches (A1, A2, BA and Bt1 horizons)
Argillic horizon - The zone from 25 to 56 inches (Bt1, Bt2 and Bt3 horizons)
Particle size control section - The zone from 25 to 45 inches (Bt1, Bt2 and part of the Bt3 horizons)