LOCATION IMMIANT IDEstablished Series
The Immiant series consists of moderately deep to bedrock, well drained
soils on foothills. They formed in material weathered from volcanic
rocks. Permeability is moderately slow. Slopes are 0 to 70 percent.
The average annual precipitation is about 13 inches and the average
annual air temperature is about 47 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Argixerolls
TYPICAL PEDON: Immiant gravelly loam - rangeland; on a 16 percent
northwest-facing slope at 4,900 feet elevation. When described on
September 12, 1980, the soil was moist throughout. (Colors are for dry
soil unless otherwise noted.)
A--0 to 10 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR
3/3) moist; weak coarse subangular blocky structure parting to very
fine subangular blocky; slightly hard, very friable, slightly sticky
and slightly plastic; many medium, fine and very fine roots; many fine
and very fine tubular pores; 20 percent pebbles and stones; neutral (pH
6.9); gradual smooth boundary. (7 to 17 inches thick)
Bt1--10 to 20 inches; yellowish brown (10YR 5/4) gravelly clay
loam, dark yellowish brown (10YR 4/4) moist; weak coarse subangular
blocky structure parting to fine subangular blocky; hard, friable,
sticky and plastic; common medium, fine, and very fine roots; many fine
and very fine tubular pores; many moderately thick clay films on ped
faces; 20 percent pebbles; neutral (pH 6.8); clear irregular boundary.
(6 to 12 inches thick)
Bt2--20 to 28 inches; dark yellowish brown (10YR 4/4) cobbly clay
loam, dark brown (7.5YR 4/4) moist; weak fine subangular blocky
structure parting to very fine subangular blocky; hard, friable, sticky
and plastic; many medium, fine and very fine roots; many fine and very
fine tubular pores; many moderately thick clay films on ped faces; 30
percent latite pebbles, cobbles, and boulders; neutral (pH 7.0); abrupt
irregular boundary. (6 to 14 inches thick)
R--28 inches; weathered latite.
TYPE LOCATION: Elmore County, Idaho; approximately 10 miles northeast
of Mountain Home, about 2,400 feet north and 2,380 feet east of the
southwest corner of section 7, T.2S., R.8E.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 47 to 50 degrees F
Depth to bedrock - 20 to 40 inches
Mollic epipedon thickness - 7 to 17 inches
Reaction in the profile - neutral to mildly alkaline
A horizon
Hue- 10YR or 7.5YR
Value- 4 or 5 dry, 2 or 3 moist
Chroma- 2 or 3
Bt horizons
Hue- 10YR or 7.5YR
Value- 4 through 6 dry
Chroma- 3 or 4
Texture - L, CL, GR-L, GR-CL, CB-L, CB-CL
Clay content - 25 to 35 percent
Rock fragments - 10 to 35 percent
Other features - a Cr horizon 2 to 4 inches thick occurs in some
pedons.
COMPETING SERIES: These are the Colma, Dragoon, Duzel, Facey,
Farrot(T), Foehlin, Glenrose, Ladd, Lobitos, Los Gatos, Mehlhorn,
Morical, Taneum, Tieton, Tweedy, and Yaxon series. Dragoon, Morical,
and Tweedy soils have a paralithic contact at 20 to 40 inches. Colma,
Facey, Foehlin, Glenrose, Ladd, Taneum, Tieton, and Yaxon soils are
greater than 40 inches deep to bedrock. Duzel soils have a average
annual soil temperature of 53 to 59 degrees F and a Bt with a
subhorizon containing more than 35 percent rock fragments. Farrot
soils contain more than 35 percent sands in the fine earth fraction.
Lobitos soils have a average annual soil temperature of 56 to 59
degrees F. Los Gatos soils have a average annual soil temperature of
54 to 59 degrees F. Mehlhorn soils have a Bt with a subhorizon
containing more than 35 percent rock fragments and a reaction that is
slightly acid.
GEOGRAPHIC SETTING: Immiant soils are on foothills at elevations of
4,000 to 5,500 feet. These soils formed in alluvium and colluvium
derived dominantly from rhyo-dacitic rocks. Slopes are 0 to 70
percent. Summers are warm and dry, and winters are cool and moist.
Average annual precipitation is 12 to 15 inches, including 1 to 3 feet
of snow. Average annual temperature is 45 to 48 degrees F and the
frost-free season is 85 to 105 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brownlee, Ruckles, and
Badge soils. Brownlee soils are deep. Ruckles soils are shallow and
clayey-skeletal. Badge soils are deep and loamy-skeletal. Brownlee
soils occupy toeslopes or northerly aspects. Ruckles soils occupy less
sloping wide ridgetops. Badge soils occupy landscape positions similar
to the Immiant series.
DRAINAGE AND PERMEABILITY: Well drained. Slow to very rapid runoff;
moderately slow permeability.
USE AND VEGETATION: Rangeland and wildlife habitat. The potential
vegetation in the natural plant community is mainly mountain big
sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southwest Idaho. These soils are
inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Elmore County Area, Idaho, 1986.
REMARKS:Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 10 inches (A horizon)
Argillic horizon - the zone from 10 to 28 inches (Bt1 and Bt2 horizons)
Lithic contact - approximately 28 inches
National Cooperative Soil Survey