LOCATION INKOM IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, frigid Cumulic Endoaquolls
TYPICAL PEDON: Inkom silt loam - on a nearly level alluvial terrace in a pasture at 4,520 feet elevation. (Colors are for dry soil unless otherwise noted.)
Ag1--0 to 3 inches; grayish brown (2.5Y 5/2) silt loam, very dark grayish brown (2.5Y 3/2) moist; weak thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; strongly effervescent; slightly alkaline (pH 7.8); abrupt smooth boundary. (2 to 5 inches thick)
Ag2--3 to 7 inches; grayish brown (2.5Y 5/2) silt loam, very dark grayish brown (2.5Y 3/2) moist; moderate thick and medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular and few fine tubular pores; common fine prominent dark yellowish brown (10YR 3/4) masses of iron accumulation; strongly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (3 to 6 inches thick)
Bg1--7 to 13 inches; gray (5Y 5/1) silt loam, very dark gray (5Y 3/1) moist; weak coarse and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; common fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (5 to 8 inches thick)
Bg2--13 to 27 inches; grayish brown (2.5Y 5/2) silt loam, very dark grayish brown (2.5Y 3/2) moist; weak coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine and few medium tubular pores; strongly effervescent; moderately alkaline (pH 8.3); clear wavy boundary. (10 to 27 inches thick)
Bg3--27 to 43 inches; gray (5Y 5/1) silt loam, dark gray (5Y 4/1) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; strongly effervescent; moderately alkaline (pH 7.9); gradual smooth boundary. (11 to 18 inches thick)
Bg4--43 to 60 inches; light gray (5Y 6/1) silt loam, dark gray (5Y 4/1) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; strongly effervescent; slightly alkaline (pH 7.8).
TYPE LOCATION: Bannock County, Idaho; about 1 mile south and 1 mile east of the town of Inkom; about 2,150 feet south and 1,350 feet east of the northwest corner of section 27, T. 7 S., R. 36 E.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 24 to 31 inches
Particle-size control section - 18 to 27 percent clay
Average annual soil temperature - 43 to 46 degrees F.
Depth to seasonal high water table - 0 to 1.5 feet during February through June
Buried A and/or B horizons are in some pedons
A horizon
Hue - 10YR, 2.5Y, or N
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 0 through 2 dry or moist
Reaction - mildly or moderately alkaline
Redoximorphic features
Hue - 10YR or 2.5Y
Value - 3 through 6 moist
Chroma - 3 through 8 moist
B horizon
Hue - 10YR, 2.5Y, 5Y, or N
Value - 4 through 8 dry, 2 through 6 moist
Chroma - 0 through 2 dry or moist
Reaction - slightly or moderately alkaline
COMPETING SERIES: There are the Bigstone and Halleck series. Bigstone soils are saturated in the moisture control section for more than 20 days following the summer solstice. Halleck soils have mollic epipedons 31 to 60 inches thick, a Cg horizon and 5GY colors in the lower layers.
GEOGRAPHIC SETTING: Inkom soils are on stream terraces and flood plains. Slopes range from 0 to 1 percent. They formed in silty alluvium derived from mixed sources. The average annual precipitation ranges from 12 to 16 inches, and the average annual temperature ranges from 42 to 45 degrees F. The frost-free season is about 80 to 100 days. Elevation ranges from 4,500 to 5,600 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arbone, Bear Lake, Downata (T), Hondoho, Joevar (T), Rexburg and Ririe soils. Bear Lake soils are very poorly drained. Joevar, Rexburg, and Ririe soils are well drained and are coarse-silty. Arbone soils are well drained and are coarse-loamy. Hondoho soils are well drained and are loamy-skeletal. Bear Lake and Downata soils are on slightly lower positions on flood plains and stream terraces. Joevar soils are on slightly higher, better drained positions on stream terraces. Rexburg and Ririe soils are on loess covered fan terraces above Inkom soils. Arbone and Hondoho soils are on fan terraces and terrace escarpments adjacent to the Inkom soils.
DRAINAGE AND PERMEABILITY: Poorly drained; runoff is very slow or ponded; permeability is moderate.
USE AND VEGETATION: The drainage has been altered on most areas of these soils. Inkom soils are now used mainly for cropland, hay, and pasture. Potential natural vegetation is mainly slender wheatgrass, streambank wheatgrass, and sedges.
DISTRIBUTION AND EXTENT: Southeastern, Idaho. This series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Bannock County, Idaho, 1983.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon (cumulic feature) - The zone from the surface to 27 inches (Ag1, Ag2, Bg1 and Bg2 horizons)
Cambic horizon - The zone from 27 to 43 inches (Bg3 horizon)
Particle-size control section - The zone from 10 to 40 inches (part of the Bg1 horizon the Bg2 horizon and part of the Bg3 horizon)