LOCATION HOBO IDEstablished Series
TAXONOMIC CLASS: Ashy over loamy, amorphic over mixed, active, frigid Alfic Udivitrands
TYPICAL PEDON: Hobo silt loam on a southwest slope of 30 percent at an elevation of 3,150 feet in a forested area. When described on September 22, 1986, the soil was moist throughout. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed needles, leaves, twigs, and moss.
Oe--1 to 1.5 inches; decomposed organic matter mixed with Mt. St. Helens volcanic ash.
A--1.5 to 3 inches; grayish brown (10YR 5/2) ashy silt loam, very dark grayish brown (10YR 3/2) moist; weak very fine and fine granular structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine and common medium roots; many very fine, fine and few medium tubular pores; slightly acid (pH 6.5); clear wavy boundary. (1 to 6 inches thick)
Bw1--3 to 8 inches; yellowish brown (10YR 5/4) ashy silt loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium subangular blocky structure parting to weak fine granular; soft, very friable, nonsticky and slightly plastic; many very fine, fine, and common medium and coarse roots; many very fine, fine and few medium tubular pores; slightly acid (pH 6.5); gradual wavy boundary. (5 to 10 inches thick)
Bw2--8 to 16 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak medium and coarse subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine and fine, common medium and coarse roots; many very fine, fine, and few medium tubular pores; neutral (pH 6.7); abrupt wavy boundary. (6 to 8 inches thick)
2E--16 to 23 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; few very fine and fine roots; common very fine and few fine tubular pores; common faint silt coatings on faces of peds; 5 percent pebbles; slightly acid (pH 6.5); gradual wavy boundary. (2 to 10 inches thick)
2Bt/E--23 to 33 inches; mixed light brown (7.5YR 6/4) and very pale brown (10YR 7/3) silt loam, dark brown (7.5YR 4/4) and brown (10YR 5/3) moist; weak coarse prismatic structure parting to moderate medium and coarse angular blocky; very hard, very firm, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and few fine tubular pores; common faint and distinct clay films on faces of peds and lining pores; 15 to 20 percent E material; 10 percent pebbles; moderately acid (pH 6.0); gradual wavy boundary. (0 to 14 inches thick)
2Bt1--33 to 46 inches; light brown (7.5YR 6/4) gravelly silty clay loam, dark brown (7.5YR 4/4) moist; moderate coarse angular blocky structure; very hard, very firm, moderately sticky and moderately plastic; few very fine roots; common very fine and few fine tubular pores; many distinct clay films on faces of peds and lining pores; common medium manganese stains; common faint silt coatings on faces of peds; 15 percent pebbles and 5 percent cobbles; strongly acid (pH 5.5); clear wavy boundary. (7 to 13 inches thick)
2Bt2--46 to 60 inches; reddish yellow (7.5YR 6/6) very gravelly clay loam, strong brown (7.5YR 4/6) moist; weak medium and coarse subangular blocky structure; very hard, very firm, moderately sticky and moderately plastic; common very fine and few fine tubular pores; common distinct clay films on faces of peds and lining pores; few fine manganese stains; common faint silt coatings on faces of peds; 25 percent pebbles and 20 percent cobbles; very strongly acid (pH 5.0).
TYPE LOCATION: Benewah County, Idaho; about 4 miles west of Emida; about 1,115 feet west and 500 feet south of the northeast corner of section 34, T. 44 N., R. 3 W.
RANGE IN CHARACTERISTICS:
Soil moisture - usually dry for 25 to 35 consecutive days, moist mid-September through July, dry August to September
Average annual soil temperature - 42 to 47 degrees F
Average summer soil temperature - 47 to 50 degrees F with an O horizon
Depth to bedrock - greater than 60 inches
Solum thickness - greater than 60 inches
Depth to perched water table - 12 to 24 inches (February to April)
Volcanic ash mantle - 14 to 20 inches
Volcanic glass content in the 0.02 to 2.0 mm fraction - 15 to 60 percent
Acid-oxalate extractable Al plus 1/2 Fe - 1.0 to 2.7 percent
Phosphate retention - 55 to 95 percent
15-bar water retention on air dried samples - 7 to 12 percent
A horizon
Hue - 10YR or 7.5YR
Value - 3 to 6 dry and 2 to 4 moist
Chroma - 2 to 4 dry or moist
Pebbles - 0 to 10 percent
Bulk density - 0.65 to 0.90 g/cc
Reaction - moderately acid to neutral
Bw horizons
Hue - 10YR or 7.5YR
Value - 5 or 6 dry and 3 or 4 moist
Chroma - 3 to 6 dry or moist
Texture - silt loam or loam
Pebbles - 0 to 10 percent
Cobbles - 0 to 5 percent
Bulk density - 0.65 to 1.00 g/cc
Reaction - moderately acid to neutral
2E horizon
Hue - 10YR, 7.5YR or 5YR
Value - 6 to 8 dry and 3 to 6 moist
Chroma - 3 to 6 moist, 2 to 6 dry
Texture - L, GR-L, CB-L, SIL, GR-SIL, CB-SIL
Pebbles - 0 to 20 percent
Cobbles - 0 to 10 percent
Reaction - moderately acid to neutral
2Bt/E horizon
Hue - 10YR, 7.5YR or 5YR
Value - 6 through 8 dry and 4 through 6 moist
Chroma - 3 through 6 dry or moist
Texture - L, GR-L, CB-L, SIL, GR-SIL, CB-SIL, SICL, GR-SICL, CB-SICL
Pebbles - 0 to 20 percent
Cobbles - 0 to 10 percent
Clay content - 18 to 30 percent
Reaction - strongly acid to slightly acid
Base saturation - 35 to 75 percent
2Bt horizon
Hue - 10YR, 7.5YR or 5YR
Value - 4 to 8 dry and 3 to 6 moist
Chroma - 3 through 6 dry or moist
Texture - SIL, L, SCL, SICL, CL, GR-SIL, GR-L, GR-SCL, GR-CL, GR-SICL, CB-SCL, CB-SICL, CB-SIL, CB-CL, or CB-L in the upper part, and GR-CL, GR-SCL, GR-L, GR-SIL, GR-SICL, GRV-SIL, GRV-CL, GRV-SCL, GRV-SICL, GRV-SL, GRV-L, or CBV-SIL, CBV-L, CBV-SCL, CB-SICL, CBV-SICL, CBV-CL in the lower part.
Rock fragments - 5 to 25 percent in the upper part and 30 to 60 percent in the lower part
Clay content - 18 to 34 percent
Reaction - very strongly acid to moderately acid
Base saturation - 35 to 75 percent
2BC horizon - present in some pedons
Hue - 10YR, 7.5YR or 5YR
Value - 7 or 8 dry and 5 or 6 moist
Chroma - 3 to 8 dry or moist
Texture - GR-L, GRV-SIL, GRV-SL
Pebbles - 15 to 35 percent
Cobbles - 5 to 15 percent
Soft fragments of decomposed rock - 15 to 35 percent
Reaction - moderately acid or slightly acid
COMPETING SERIES: These are the Bargamin (T), Berray (T), Odonnell(T) and Revling series. Bargamin soils have more than 34 percent clay in the lower part of the argillic horiozn. Berray soils have horizons containing lamellae. Revling soils do not have E horizons. Odonnell soils have less than 10 percent rock fragments in the lower part of the argillic horizon.
GEOGRAPHIC SETTING: Hobo soils are on all aspects of dissected terraces and foothills. Slopes range from 5 to 35 percent. These soils formed in colluvium and old alluvium derived dominantly from shale, quartzite, or mica schist, with a thick mantle of volcanic ash. Elevations range from 1,600 to 4,000 feet. The average annual air temperature ranges from 42 to 46 degrees F, and average annual precipitation is 30 to 50 inches. The frost-free period is from 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the tentative Bouldercreek(T), Honeyjones(T), and Hugus(T) soils and the Helmer soils. Bouldercreek and Honeyjones soils are on steeper, convex, north-facing mountainsides and are ashy over loamy-skeletal. Hugus soils are on steeper, north-facing, convex, dissected terrace slopes and foothills, and are loamy-skeletal. Helmer soils are on concave terraces and have a fragipan.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium to very rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used for timber production, livestock grazing, recreation, wildlife habitat, hay and pasture, and homesites. Potential natural vegetation is mainly western hemlock, western redcedar, western white pine, grand fir, Douglas-fir, western larch, and lodgepole pine, with an understory of queencup beadlily, American trailplant, Columbia brome, violet, starry false-Solomon's-seal, sweetscented bedstraw, goldthread, Oregon fairybells, oneleaf foamflower, piper anemone, northern twinflower, and western rattlesnake plantain.
DISTRIBUTION AND EXTENT: Northern Idaho. This soil is moderately extensive.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Shoshone County, Idaho, 1993.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the mineral surface to 3 inches (A horizon).
Cambic horizon - the zone from 3 to 16 inches (Bw1 and Bw2 horizons)
Albic horizon (not present in all pedons) - the zone from 16 to 23 inches (2E horizon).
Glossic horizon - the zone from 23 to 33 inches (2Bt/E horizon).
Argillic horizon - the zone from 23 to 60 inches (2Bt/E, 2Bt1, 2Bt2 horizons).
Volcanic ash mantle - the zone from the mineral surface to 16 inches (A, Bw1, and Bw2 horizons).
Particle-size control section - the zone from the mineral surface to 40 inches (A, Bw1, Bw2, 2E, 2Bt/E and part of the 2Bt1 horizons).
ADDITIONAL DATA: Soil Survey Sample Number: S89ID-079-004. NSSL Sample Number: 89P748.