LOCATION SCISM IDEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Xereptic Haplodurids
TYPICAL PEDON: Scism silt loam -- on a nearly level upland area at 2,700 feet elevation in cropland. (Colors are for air dry soil unless otherwise noted.)
Ap--0 to 8 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; common fine roots; many very fine pores; few fine gravel and duripan fragments; slightly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (2 to 11 inches thick)
Bk1--8 to 13 inches; light gray (10YR 7/2) silt loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many very fine to medium roots; many very fine and fine pores; about 5 percent weakly cemented rounded nodules or (cicada) krotovinas; 1 to 2 cm in diameter and 1.5 to 3 cm in length; strongly effervescent; moderately alkaline (pH 8.2); gradual smooth boundary. (5 to 15 inches thick)
Bk2--13 to 21 inches; light gray (10YR 7/2) silt loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, slightly sticky slightly plastic; many very fine to medium roots; common very fine tubular pores; 40 percent nodules similar to those described above; strongly effervescent, few fine veins of calcium carbonates; strongly alkaline (pH 8.5); abrupt smooth boundary. (7 to 17 inches thick)
Bkqm--21 to 30 inches; light gray (10YR 7/2) weakly cemented duripan with silt loam soil material between plates, grayish brown (10YR 5/2) moist; massive; hard, very firm; common very fine and fine roots matted at surface; violently effervescent; strongly alkaline (pH 8.7); gradual smooth boundary. (4 to 20 inches thick)
Bkq--30 to 42 inches; light gray (10YR 7/2) light silt loam, dark grayish brown (10YR 4/2) moist; massive; hard, very firm, nonsticky and slightly plastic; few very fine and fine roots; common very fine tubular pores; violently effervescent, few veins and common splotches of calcium carbonates; strongly alkaline (pH 8.5); abrupt smooth boundary. (0 to 10 inches thick)
2C--42 to 62 inches; pale brown (10YR 6/3) light loam, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, few very fine roots and pores; few fine pieces of duripan; strongly effervescent, few splotches of calcium carbonates 1 to 5 cm in diameter; moderately alkaline (pH 8.3).
TYPE LOCATION: Canyon County, Idaho; about 8 miles south and 5 miles west of Nampa; 700 feet south and 70 feet west of NE corner of section 10, T.1 N., R.3 W.; USGS Givens Hot Springs Quadrangle; (Latitude - 116 degrees, 40 minutes, 21 seconds N. and Longitude - 43 degrees, 26 minutes, 34 seconds W.).
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 47 to 56 degrees F.
Depth to duripan - 20 to 40 inches
Depth to bedrock - greater than 60 inches
Particle-size control section - 12 to 18 percent clay
Moisture control section - moist less than 90 consecutive days when the soil temperature is greater than 47 degrees F.
A horizon
Hue - 2.5Y or 10YR
Value - 5 through 7 dry, 3 through 5 moist
Chroma - 2 through 4 dry or moist
Reaction (pH) - slightly or moderately alkaline
Calcium carbonate equivalent - 0 to 10 percent
Bk horizon
Hue - 2.5Y or 10YR
Value - 6 through 8 dry, 4 through 6 moist
Chroma - 2 through 5 dry or moist
Texture - SIL or VFSL
Clay content - 12 to 18 percent
Nodules or krotovinas - 10 to 50 percent
Reaction (pH) - moderately alkaline or strongly alkaline
Calcium carbonate equivalent - 15 to 40 percent
2C horizon
Texture - SIL, L, or SL
COMPETING SERIES: There are no other series in this classification. A closely related soils is the Portneuf series. Portneuf soils lack duripans.
GEOGRAPHIC SETTING: Scism soils are on lava plains, shield volcanoes, calderas, terraces, draws, and tablelands at elevations of 2,000 to 5,000 feet. Slopes range from 0 to 20 percent, but most commonly are less than 8 percent. These soils formed in loess and weathered volcanic ash over loamy alluvium from lacustrine deposits, volcanic ash and basalt. Average annual precipitation is 8 to 11 inches, including up to 25 inches of snow. Average annual temperature is 45 to 54 degrees F. Frost-free period is 100 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Minidoka, Vickery, and Purdam soils. Purdam soils have an argillic horizon. Minidoka and Vickery soils have an indurated duripan. Minidoka, Vickery, and Purdam soils are on landscape positions similar to Scism soils.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Scism soils are used mainly for irrigated cropland and in some areas rangeland and wildlife habitat. The principal crops are alfalfa, corn, sugar beets, small grains, potatoes, and onions. Dominant natural vegetation is Wyoming big sagebrush, Sandberg bluegrass, Thurber needlegrass, and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southwestern Idaho; MLRA 11. This series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Canyon County, Idaho, 1973.
REMARKS: Diagnostic horizons and other features recognized in this pedon:
Ochric epipedon - the zone from the surface to 8 inches (Ap horizon)
Haplic duripan - the zone from 21 to 30 inches (Bkqm horizon)
Calcic horizon - the zone from 8 to 42 inches (Bk1, Bk2, Bkqm and Bkq horizons)
Particle-size control section - the zone from 10 to 21 inches
Soil moisture regime - aridic bordering xeric
Geographic setting - terms used throughout MLRA 11 to identify the setting of this soil are quite varied although all equate to the same landscape. There will be further investigation from an MLRA project level as to the accepted terms for use.
Classificaiton of this pedon reflects a revision as of 4/00 from coarse-silty, mixed, mesic Haploxerollic Durorthids to coarse-silty, mixed, superactive, mesic Xereptic Haplodurids based on revisions to Soil Taxonomy.
Bedrock substratum phases of the Scism series will no longer meet the series concent and will be new soils. (see Ada County Area, Idaho soil survey).
More investigation is needed on this series to determine the presence of sodium and/or salts.