LOCATION BLACKOTTER IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Aeric Calciaquolls
TYPICAL PEDON: Blackotter loam, nonirrigated hayland; on a 0.5 percent slope at 6,070 feet with grass hay, rushes and sedges. When described on August 21, 1991, the soil was moist from 40 to 61 inches and a water table was at 61 inches. (Colors are for dry soil unless otherwise noted.)
A1--0 to 2 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate medium platy structure parting to moderate fine and medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; few very fine irregular and few very fine and fine tubular pores; strongly effervescent (4 percent calcium carbonate equivalent); disseminated lime; moderately alkaline (pH 8.2); abrupt smooth boundary. (2 to 4 inches thick)
A2--2 to 8 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, medium and coarse roots; few very fine and fine tubular pores; strongly effervescent (2 percent calcium carbonate equivalent); disseminated lime; 2 percent gravel; strongly alkaline (pH 8.9); abrupt smooth boundary. (4 to 7 inches thick)
Bw--8 to 11 inches; brown (10YR 5/3) loam, dark grayish brown (10YR 4/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and few fine tubular pores; strongly effervescent (5 percent calcium carbonate equivalent); disseminated lime; 2 percent gravel; strongly alkaline (pH 8.8); abrupt wavy boundary. (0 to 3 inches thick)
Bk1--11 to 20 inches; very pale brown (10YR 8/2) clay loam, pale brown (10YR 6/3) moist, few fine distinct very dark grayish brown (10YR 3/2) and few medium faint dark grayish brown (10YR 4/2) moist redox depletions; moderate medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and few fine tubular pores; violently effervescent (38 percent calcium carbonate equivalent); disseminated lime and lime segregated as common fine and medium irregularly shaped soft masses and soft seams; strongly alkaline (pH 8.6); clear wavy boundary.
Bk2--20 to 37 inches; very pale brown (10YR 7/3) very fine sandy loam, brown (10YR 5/3) moist, common fine distinct dark brown (10YR 3/3) and yellowish brown (10YR 5/6) moist redox concentrations; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine and few fine tubular pores; violently effervescent (22 percent calcium carbonate equivalent); disseminated lime and lime segregated as few fine irregularly shaped soft masses; moderately alkaline (pH 8.4); clear irregular boundary. (combined thickness of the Bk horizons 24 to 26 inches)
2C1--37 to 50 inches; multicolored very gravelly coarse sand; single grain; loose; common very fine and few fine roots; common very fine and few fine irregular pores; strongly effervescent (12 percent calcium carbonate equivalent); disseminated lime; 30 percent gravel greater than 5mm, 10 percent gravel less than 5mm, 10 percent cobbles; strongly alkaline (pH 8.5); gradual irregular boundary. (13 to 14 inches thick)
2C2--50 to 61 inches; multicolored extremely gravelly sand; single grain; loose; few very fine and few fine roots; common very fine and few fine irregular pores; strongly effervescent (14 percent calcium carbonate equivalent); disseminated lime; 30 percent gravel greater than 5mm, 10 percent gravel less than 5mm, 30 percent cobbles; strongly alkaline (pH 8.5).
TYPE LOCATION: Bear Lake County, Idaho; about 11 miles south of Geneva; about 200 feet west and 500 feet north of the southeast corner of section 23, T.14S., R.46E. Latitude - 42 degrees, 11 minutes, 4 seconds north. Longitude - 111 degrees, 2 minutes, 51 seconds west.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 8 to 11 inches
Depth to redox features - 10 to 18 inches
Depth to seasonal high water table - 10 to 18 inches December through May
Depth to lithologic discontinuity - 34 to 37 inches
Average annual soil temperature - 42 to 45 degrees F.
Clay content - averages: upper part - 14 to 18 percent, lower part - 0 to 5 percent
An O horizon is present in some pedons
A horizons
Hue - 10YR to 5Y
Value - 4 or 5 dry
Chroma - 0 to 2 moist
Reaction - moderately or strongly alkaline
Bw horizon
Hue - 10YR through 5Y
Value - 4 to 6 dry; 4 or 5 moist
Chroma - 1 to 3 dry or moist
Reaction - moderately or strongly alkaline
Bk horizons
Value - 6 to 8 dry, 3 to 6 moist
Chroma - 2 or 3 dry or moist
Effervescence - strong or violent
Calcium carbonate equivalent - 15 to 40 percent
Reaction - moderately or strongly alkaline
2C horizons
Texture - GRV-COS, GRX-COS, GRX-LS, GRV-LS, GRX-S or CBX-S
Rock fragment content - 35 to 80 percent
Effervescence - slight or strong
Calcium carbonate equivalent - 5 to 15 percent
Reaction - slightly to strongly alkaline
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Blackotter soils are on floodplains and low terraces. Slopes range from 0 to 2 percent. Elevations range from 5,800 to 6,500 feet. These soils formed in silty alluvium over coarse textured alluvium. The average annual precipitation ranges from 12 to 18 inches, the average annual air temperature is 39 to 43 degrees F and the frost free season is 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bear Lake and Lago (T) soils. Bear Lake and Lago soils have a fine-silty particle size-control section. They are on smooth to concave slopes on the inside curves of the Bear River and on wider valley bottoms than Blackotter soils.
DRAINAGE AND PERMEABILITY: Poorly drained; slow runoff; moderate permeability in the upper part and very rapid in the lower part; rare flooding for brief periods April through June.
USE AND VEGETATION: Blackotter soils are used for nonirrigated hayland and pasture. The native vegetation is Nebraska sedge, sedges, cinquefoil, slender wheatgrass and tufted hairgrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Bear Lake County, Idaho, 2008. The name is coined from a nearby irrigation canal.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to 8 inches (the A1 and A2 horizons)
Calcic horizon - the zone from 11 to 37 inches (the Bk1 and Bk2 horizons)
Aeric subgroup - based on chroma of 2 directly below the A horizon.
Particle-size control section - the zone from 10 to 40 inches (part of the Bw, the Bk1, Bk2 and part of the 2C1 horizons)
ADDITIONAL DATA: This soil was sampled for analysis (partial characterization) at the NSSL, Lincoln, NE. Laboratory sample number is RP92-ID-27 (Soil Survey sample number - S91ID007004)