LOCATION AMMON ID+OREstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Calcidic Haploxerolls
TYPICAL PEDON: Ammon silt loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A11--0 to 2 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak thin platy structure, parting to weak very fine granular; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine interstitial pores; moderately calcareous; mildly alkaline (pH 7.4); clear smooth boundary. (0 to 4 inches thick)
A12--2 to 10 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak very fine and medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and fine tubular pores; moderately calcareous; mildly alkaline (pH 7.4); gradual smooth boundary. (6 to 12 inches thick)
C1--10 to 19 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine tubular pores; many hard cicada krotovinas with weak lime coatings on outside; moderately calcareous; moderately alkaline (pH 8.0); gradual smooth boundary. (10 to 25 inches thick)
C2--19 to 34 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine tubular pores; many hard cicada krotovinas with weak lime coatings on outside; moderately calcareous; moderately alkaline (pH 8.0); gradual smooth boundary. (0 to 20 inches thick)
C3--34 to 53 inches; light gray (10YR 7/2) light silt loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine tubular pores; common hard cicada krotovinas with weak lime coatings on outside; moderately calcareous; moderately alkaline (pH 8.4); gradual smooth boundary. (10 to 25 inches thick)
C4--53 to 60 inches; light gray (10YR 7/2) light silt loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; few very fine and fine tubular pores; few hard cicada krotovinas with weak lime coatings on outside; moderately calcareous; moderately alkaline (pH 8.2). (0 to several feet thick)
TYPE LOCATION: Bingham County, Idaho; on edge of deep wash in a very gently sloping fan about 2 miles north of Goshen; 2,640 feet south and 525 feet west of the nE corner sec. 13, T. 1 S., R. 37 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 41 degrees to 47 degrees F., and the mean summer soil temperature at a depth of 20 inches ranges from 59 degrees to 65 degrees F. The soils are usually dry, and are dry between depths of 4 and 12 inches for about 70 to 80 days in late summer. The 10- to 40-inch control section is dominantly silt loam and averages 8 to 18 percent clay and less than 15 percent particles coarser than very fine sand. The organic matter decreases regularly with increasing depth to a level of 0.5 percent or less within a depth of 50 inches. The mollic epipedon is 7 to 15 inches thick.
The Ap or A1 horizon when mixed to 7 inches has chroma of 2 or 3. It has weak or moderate platy or weak granular structure, and 1.2 to 2.5 percent organic matter. This horizon ranges from noncalcareous to moderately calcareous.
The C horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry and 3 through 5 moist, and chroma of 2 or 3. It is massive or has weak granular, very weak subangular blocky, or very weak prismatic structure. This horizon contains 0 to 20 percent hard nodules of soil material or cicada krotovinas. It is moderately or slightly calcareous and contains less than 15 percent calcium carbonate, and has some soft powdery secondary lime above a depth of 43 inches.
COMPETING SERIES: This is the Newdale series. Newdale soils have a calcic horizon with the upper boundary at a depth of 10 to 18 inches.
GEOGRAPHIC SETTING: Ammon soils are in level or gently sloping alluvial fans and foot slopes adjacent to the loessal uplands. Elevations range from 4,200 to 5,800 feet. Slopes range from 0 to 8 percent. The soils formed in deep alluvium from loessal materials. the climate is semiarid with dry summer. Mean annual precipitation is 8 to 12 inches, including 2 to 5 feet of snowfall. Average freeze-free period is 94 to 126 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Newdale soils and the Pocatello and Wheeler soils. Pocatello and Wheeler soils have a mean annual soil temperature warmer than 47 degrees F.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.
USE AND VEGETATION: Mostly cultivated under irrigation for hay, pasture, potatoes, sugar beets, and small grains. The principal native plants are big sagebrush, rabbitbrush, bluebunch wheatgrass and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: The series is inextensive in the Upper Snake River Valley and adjacent areas in eastern Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Bingham County (Blackfoot-Aberdeen Area), Idaho, 1938.