LOCATION ALPON IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Palecryolls
TYPICAL PEDON: Alpon silt loam - forest (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed needles and twigs; abrupt wavy boundary. (0 to 1.5 inches thick)
A--1 to 13 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; slightly hard, very friable, nonsticky, slightly plastic; common very fine and fine roots; many very fine and fine tubular pores; 5 percent reddish brown sandstone gravel with few dark gray manganese stains; strongly acid (pH 5.5); gradual smooth boundary. (11 to 16 inches thick)
E1--13 to 23 inches; pink (7.5YR 7/3) silt loam, dark brown (7.5YR 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky, slightly plastic; common very fine and fine roots; many very fine and fine tubular pores; common partially coated silt particles; 5 percent light brown sandstone gravel; moderately acid (pH 5.9); gradual smooth boundary. (6 to 14 inches thick)
E2--23 to 35 inches; pink (7.5YR 7/3) silt loam, brown (7.5YR 4/2) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common very fine and fine roots; common very fine and fine tubular pores; few uncoated but mostly partially coated silt particles; 5 percent pink sandstone gravel; neutral (pH 6.6); gradual wavy boundary. (8 to 15 inches thick)
E3--35 to 46 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, nonsticky, nonplastic; common very fine and fine roots; common very fine and fine tubular pores; many uncoated silt particles; 3 percent sandstone gravel; slightly acid (pH 6.5); clear wavy boundary. (8 to 12 inches thick)
Bt1--46 to 58 inches; light brown (7.5YR 6/4) and light yellowish brown (10YR 6/4) clay loam, dark brown (7.5YR 4/4) and dark yellowish brown (10YR 4/4) moist; common uncoated light gray (10YR 7/2) silt grains on peds; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky, moderately plastic; common very fine and fine roots; many very fine and fine tubular pores; many medium continuous distinct clay films on surfaces of peds; 5 percent angular fine gravel; slightly acid (pH 6.4); gradual wavy boundary. (6 to 15 inches thick)
Bt2--58 to 64 inches; light brown (7.5YR 6/4) clay loam, dark brown (7.5YR 4/4) moist; light gray (10YR 7/2) interior of some peds, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky, moderately plastic; few very fine and medium roots; common very fine and fine tubular pores; many prominent reddish brown (5YR 4/4) clay films on surfaces of peds and continuous clay films in channels; common uncoated silt grains on peds; 12 percent paragravel sandstone fragments; slightly acid (pH 6.4); gradual wavy boundary. (4 to 10 inches thick)
BCt--64 to 67 inches; light gray (2.5Y 7/2) loam, light brownish gray (2.5Y 6/2) moist; weak coarse subangular blocky structure; very hard, firm, slightly sticky, slightly plastic; few very fine and coarse roots; few very fine tubular pores; common distinct clay films on surfaces of peds and in pores; common light reddish brown (5YR 6/3) moderately weathered sandstone fragments, reddish brown (5YR 5/4) moist; slightly acid (pH 6.5); abrupt wavy boundary. (2 to 8 inches thick)
Crt--67 to 70 inches; light reddish brown (2.5YR 6/4) weathered fine-grained sandstone, reddish brown (2.5YR 4/4) moist; few spots of light gray (2.5Y 7/1); common distinct clay films in cracks; slightly acid (pH 6.3); abrupt smooth boundary. (0 to 6 inches thick)
R--70 inches; pale red (2.5YR 6/2), slightly weathered, fine-grained sandstone, reddish brown (2.5YR 4/4) moist; moderately alkaline (pH 8.0).
TYPE LOCATION: Bingham County, Idaho; about 9 miles south and 2 miles west of Bone on a northeast-facing mountain having a slope of 40 percent and at an elevation of 6,800 feet; 300 feet south and 500 feet west of the center of sec. 1, T.3S., R.39E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 35 to 42 degrees F.; and the mean summer soil temperature and where there is a very thin or no 0 horizon, ranges from 50 to 59 degrees F. The soils are usually moist (udic moisture regime). Depth to the argillic horizon ranges from 36 to 50 inches. The depth to sandstone or other bedrock is more than 60 inches. The sola are 45 to 70 inches thick. The mollic epipedon is 11 to 16 inches thick. The A1 horizon has dry value of 4 to 5, moist value of 2 to 3, and chroma of 2 or 3. When mixed to 7 inches, it probably has a base saturation of 50 to 60 percent and 3 to 7 percent organic matter having a C:N ratio of 13.5 to 19. This horizon is strongly or moderately acid. The E horizon has hue of 10YR or 7.5YR, value of 6 or 7 dry and 4 or 5 moist, and chroma of 3 or 2. It is silt loam or loam and is 25 to 40 inches thick. This horizon is moderately acid to neutral and the argillic horizon is 12 to 24 inches thick. The Bt horizon has hue of 7.5YR or 10YR, value of 5 through 7 dry and 4 through 6 moist, and chroma of 2 through 5. It is clay loam or silty clay loam and averages 27 to 35 percent clay, more than 15 percent particles coarser than very fine sand, and less than 15 percent rock fragments. This horizon has weak to moderate, fine to medium subangular blocky structure. It is slightly acid to neutral. It has continuous prominent to few faint clay films. This horizon probably has between 60 and 75 percent base saturation. It is 36 to 50 inches thick.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The soils are on moderately steep and steep, northerly, mountainous slopes at elevations of 6,000 to 8,000 feet. Slopes range from 20 to 60 percent. The soils formed in loess overlying residuum weathered from sandstone or colluvium from sandstone. Mean annual precipitation is 18 to 24 inches, including 6 to 12 feet of snowfall. Summer showers are common. The frost-free period is 20 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dranyon, Greys, and Pavohroo soils. Dranyon and Greys soils have the depth to the top of the argillic horizon above 24 inches. Pavohroo soils lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well-drained; permeability is moderately slow.
USE AND VEGETATION: Used mainly for grazing and timber production. Dominant native plants are subalpine fir, Douglas-fir, lodgepole pine, aspen, and pinegrass.
DISTRIBUTION AND EXTENT: The series is of moderate extent in the high mountainous areas in southeastern Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Bingham County, Idaho, 1972.
REMARKS: The soils were classified formerly as Gray-Brown Podzolic soils.