LOCATION HOFF IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Lithic Ultic Argixerolls
TYPICAL PEDON: Hoff gravelly ashy loam -- on a 28 percent convex west-facing slope at 5,280 feet elevation in open forestland. When described on October 12, 1994, the soil was moist to 7 inches and dry below. (Colors are for air-dry soil unless otherwise noted.)
A--0 to 6 inches; dark brown (7.5YR 3/3) gravelly ashy loam, very dark brown (7.5YR 2.5/2) moist; moderate fine granular structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine, medium and coarse roots; many very fine, fine and medium irregular pores; 25 percent gravel; neutral (pH 6.9); clear wavy boundary. (3 to 7 inches thick)
AB--6 to 11 inches; brown (7.5YR 4/3) very gravelly ashy loam, very dark brown (7.5YR 2.5/3) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and moderately plastic; many very fine, fine, medium and coarse roots; many very fine, fine and medium irregular pores; 40 percent gravel and 10 percent cobbles; slightly acid (pH 6.1); clear wavy boundary. (0 to 6 inches thick)
Bt--11 to 19 inches; brown (7.5YR 4/3) extremely cobbly ashy clay loam, dark brown (7.5YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine and fine, common medium and coarse roots; common very fine, fine and medium tubular and irregular pores; common faint clay films on faces of peds and in pores; 35 percent gravel and 40 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (3 to 10 inches thick)
R--19 inches; fractured basalt.
TYPE LOCATION: Boise County, Idaho; about 5 miles northwest of Banks; 2,400 feet north and 1,600 feet east of the southwest corner of section 15, T.9 N., R.2 E.; USGS Dry Buck Valley Quadrangle; Latitude - 44 degrees, 06 minutes, 57 seconds N. and Longitude - 116 degrees, 12 minutes, 34 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 10 to 20 inches
Depth to bedrock - 10 to 20 inches
Base saturation - 50 to 75 percent
Volcanic glass content - 5 to 20 percent
Acid oxalate extract A1+1/2 Fe - 0.4 to 1.2 percent
Moisture control section - dry 60 to 75 consecutive days following the summer solstice
Mean annual soil temperature - 41 to 47 degrees F.
A horizon
Hue - 7.5YR or 10YR
Value - 3 or 4 dry; 2, 2.5 or 3 moist
Chroma - 2 or 3 dry or moist
Rock fragments - 15 to 35 percent gravel, 0 to 10 percent cobbles and 15 to 35 percent total
Reaction - slightly acid or neutral
Bt horizon
Hue - 7.5YR or 10YR
Value - 4 or 5 dry; 2.5, 3 or 4 moist
Chroma - 2 through 4 dry or moist
Texture - ASHY-L or ASHY-CL
Clay content - 20 to 30 percent
Rock fragments - 25 to 60 percent gravel, 0 to 50 percent cobbles and 35 to 80 percent total
Reaction - moderately acid through neutral
COMPETING SERIES: There are no other soils recognized in this family. Gaib soils are closely related, but do not have ashy textures.
GEOGRAPHIC SETTING: Hoff soils are on summits and slopes of hills and mountains at elevations of 3,800 to 7,050 feet. Slopes range from 8 to 65 percent. These soils formed in colluvium and residuum weathered from basalt and volcanic ash. The average annual precipitation is 24 to 36 inches. The average annual temperature is 39 to 45 degrees F. The frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cleymor, Highvalley, Longs and Shilling soils. Cleymor soils are clayey, very deep and occur on concave geomorphic positions. Highvalley, Longs and Shilling soils are greater than 40 inches deep and occur on less convex geomorphic positions.
DRAINAGE AND PERMEABILITY: Well drained; rapid to very rapid runoff; moderately slow permeability.
USE AND VEGETATION: Hoff soils are used mainly for woodland grazing and wildlife habitat. The dominant natural vegetation is mountain big sagebrush, bluebunch wheatgrass, white spirea, and scattered ponderosa pine.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 43b. Hoff soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and other features recognized in this pedon:
Mollic epipedon - zone from the soil surface to 19 inches (A, AB and Bt horizons)
Argillic horizon - zone from 11 to 19 inches (Bt horizon)
Lithic contact - at 19 inches (R)
Particle-size control section - zone from 11 to 19 inches
Soil moisture regime - xeric