LOCATION ISMAY MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, frigid Aridic Ustifluvents
TYPICAL PEDON: Ismay silty clay loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 8 inches; light yellowish brown (2.5Y 6/4) silty clay loam, olive brown (2.5Y 4/4) moist; moderate fine and medium granular structure; hard, firm, sticky and plastic; common medium and fine roots and many very fine roots; common very fine pores; few fine masses of salt and gypsum; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 8 inches thick)
C1--8 to 17 inches; light yellowish brown (2.5Y 6/4) silty clay loam that has very thin strata of fine sandy loam and silt loam, olive brown (2.5Y 4/4) moist; massive; hard, firm, sticky and plastic; common medium, fine, and very fine roots; common fine and very fine pores; few fine masses of salt and gypsum; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (6 to 12 inches thick)
C2--17 to 25 inches; light yellowish brown (2.5Y 6/4) silt loam that has very thin strata of fine sandy loam, loam, and silty clay loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common medium, fine, and very fine roots; many very fine pores, few fine pores; few fine masses of salt and gypsum; strongly effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (8 to 20 inches thick)
C3--25 to 50 inches; light yellowish brown (2.5Y 6/4) loam that has very thin strata of fine sandy loam, silt loam, and clay loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few medium roots, common fine and very fine roots; common very fine pores, few fine pores; few fine masses of salt and gypsum; strongly effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (14 to 30 inches thick)
C4--50 to 60 inches; light yellowish brown (2.5Y 6/4) loam that has very thin strata of fine sandy loam, silt loam, and clay loam, olive brown (2.5Y 4/4) moist; common fine distinct yellowish brown (10YR 5/6) redox concentrations and few fine faint dark grayish brown (10YR 4/2) redox concentrations; massive; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; few very fine pores; few fine masses of salt and gypsum; strongly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Prairie County, Montana; 900 feet north and 1,700 feet east of the SW corner of sec. 28, T. 12., R. 55 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches, dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees F or higher.
Depth to seasonal high water table - 42 to 60 inches for a short period during May or June.
A horizon - Hue: 2.5Y or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3, or 4
Clay content: 27 to 40 percent
Calcium carbonate equivalent: 5 to 10 percent
EC: 2 to 8 mmhos/cm
SAR: 5 to 20
Reaction: pH 7.4 to 9.0
C1 horizon - Chroma: 2, 3, or 4
Texture: silty clay loam, loam, clay loam, or silt loam with or without thin strata of fine sandy loam, silty clay loam, loam, clay loam, or silt loam
Clay content: 18 to 35 percent, 15 to 40 percent sand with less than 15 percent fine sand or coarser
Calcium carbonate equivalent: 5 to 10 percent
EC: 8 to 16 mmhos/cm
SAR: 13 to 20
Reaction: pH 7.9 to 9.0
C2 horizon - Chroma: 2, 3, or 4
Texture: silt loam, loam, or silty clay loam with thin strata of very fine sandy loam, loam, silt loam, clay loam, or silty clay loam
Clay content: 18 to 35 percent, 15 to 40 percent sand with less than 15 percent fine sand or coarser
Calcium carbonate equivalent: 5 to 10 percent
EC: 4 to 16 mmhos/cm
SAR: 13 to 30
Reaction: pH 7.9 to 9.0
C3 horizon - Chroma: 2, 3, or 4
Texture: loam, silt loam, or clay loam with thin strata very fine sandy loam, loam, silt loam, or clay loam
Clay content: 18 to 35 percent, 15 to 40 percent sand with less than 15 percent fine sand or coarser
Calcium carbonate equivalent: 5 to 10 percent
EC: 4 to 16 mmhos/cm
SAR: 10 to 35
Reaction: pH 7.9 to 9.0
C4 horizon - Chroma: 2, 3, or 4
Texture: loam or clay loam with thin strata of very fine sandy loam, loam, silt loam, clay loam, or silty clay loam
Clay content: 18 to 35 percent, 15 to 40 percent sand with less than 15 percent fine sand or coarser
Calcium carbonate equivalent: 5 to 10 percent
EC: 4 to 16 mmhos/cm
SAR: 5 to 35
Reaction: pH 7.9 to 9.0
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - stream terraces; flood plains.
Elevation - 2,200 to 3,000 feet.
Slope- 0 to 2 percent.
Parent material - stratified alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 100 to 135 days.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderately slow permeability.
USE AND VEGETATION: Ismay soils are used as rangeland. The potential native vegetation is alkali sacaton, Nuttall alkaligrass, western wheatgrass, and alkali bluegrass.
DISTRIBUTION AND EXTENT: Ismay soils are of small extent in southeastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Prairie County, Montana, 1986.
REMARKS: Soil interpretation records: MT1006. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 8 inches (A horizon); an irregular decrease in organic carbon content with increasing depth; a fine-silty particle-size control section (C1, C2, C3 horizons). Ismay soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.