LOCATION ANTWERP            MT
Established Series
Rev. JAL
11/98

ANTWERP SERIES


The Antwerp series consists of very deep, well drained soils that formed in alluvium. These soils are on alluvial fans, stream terraces and sedimentary plains. Slopes are 0 to 4 percent. Mean annual precipitation is about 10 inches, and mean annual temperature is about 42 degrees F.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, frigid Aridic Ustorthents

TYPICAL PEDON: Antwerp silty clay loam, grassland (colors are for dry soil unless otherwise noted).

A--0 to 1 inch; light gray (2.5Y 7/2) silty clay loam, grayish brown (2.5Y 5/2) moist; weak fine platy structure; slightly hard, friable, slightly sticky and plastic; common fine and very fine roots; common very fine tubular pores; strongly alkaline (pH 8.6); abrupt smooth boundary. (1/2 inch to 3 inches thick)

Bw--1 inch to 6 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak medium angular blocky structure; hard, friable, sticky and plastic; common fine and very fine roots; common very fine irregular pores; strongly effervescent; very strongly alkaline (pH 9.2); abrupt smooth boundary. (0 to 7 inches thick)

Bz1--6 to 15 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak medium angular blocky structure; hard, friable, sticky and plastic; few very fine roots; few very fine irregular pores; many fine masses of salt; strongly effervescent; strongly alkaline (pH 9.0); clear smooth boundary. (8 to 22 inches thick)

Bz2--15 to 24 inches; light olive brown (2.5Y 5/4) silty clay loam, olive brown (2.5Y 4/4) moist; weak fine granular structure; slightly hard, friable, slightly sticky and plastic; few very fine roots; few very fine irregular pores; common medium masses of salt; strongly effervescent; moderately alkaline (pH 8.4); gradual irregular boundary. (8 to 26 inches thick)

BC--24 to 60 inches; grayish brown (2.5Y 5/2) silt loam, dark grayish brown (2.5Y 4/2) moist; massive; soft, friable, slightly sticky and slightly plastic; strongly effervescent; moderately alkaline (pH 8.4); gradual irregular boundary.

TYPE LOCATION: Rosebud County, Montana; 600 feet north and 30 feet west of the SE corner of sec. 28, T. 9 N., R. 40 E.

RANGE IN CHARACTERISTICS:

Soil temperature - 41 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 or higher.

A horizon - Hue: 2.5Y or 10YR

Value: 6 or 7 dry; 4 or 5 moist

Chroma: 2 or 3

Texture: silty clay loam, silt loam, or loam

Clay content: 20 to 33 percent

Electrical conductivity: less than 2 mmhos/cm

Reaction: pH 7.9 to 9.0

Bw horizon - Hue: 2.5Y or 10YR

Value: 5 or 6 dry; 4 or 5 moist

Chroma: 2 or 3

Texture: silty clay loam or silt loam

Clay content: 27 to 35 percent

Calcium carbonate equivalent: 5 to 10 percent

Electrical conductivity: 2 to 8 mmhos/cm

SAR: 10 to 30

Reaction: pH 7.9 to 9.6

Bz horizons - Hue: 2.5Y or 10YR

Value: 5 or 6 dry; 4 or 5 moist

Chroma: 2, 3, or 4

Texture: silty clay loam or silt loam

Clay content: 20 to 35 percent

Calcium carbonate equivalent: 5 to 10 percent

Electrical conductivity: 8 to 16 mmhos/cm

SAR: 15 to 40

Reaction: pH 7.9 to 9.0

BC horizon - Hue: 2.5Y or 5Y

Value: 5 or 6 dry; 4 or 5 moist

Chroma: 2, 3, or 4

Texture: silt loam or silty clay loam

Clay content: 20 to 35 percent

Calcium carbonate equivalent: 5 to 10 percent

Electrical conductivity: 8 to 24 mmhos/cm

SAR: 15 to 30

Reaction: pH 7.9 to 9.0

COMPETING SERIES:

Lambeth (MT) - has horizons of gypsum accumulations; has relict mottles at depths of 12 inches.

GEOGRAPHIC SETTING:

Landform - alluvial fans, stream terraces and sedimentary plains.

Elevation - 1,900 to 3,500 feet.

Slope- 0 to 4 percent.

Climate - long cold winters; moist springs; warm summers.

Parent material - alluvium.

Mean annual precipitation - 10 to 14 inches.

Mean annual temperature - 39 to 45 degrees F.

Frost free period - 100 to 135 days.

DRAINAGE AND PERMEABILITY: Well drained; slow permeability.

USE AND VEGETATION: Antwerp soils are used mainly for rangeland. Potential native vegetation is mainly western wheatgrass, alkali sacaton, and Nuttall saltbush.

DISTRIBUTION AND EXTENT: Antwerp soils are of moderate extent in southeastern Montana.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED: Rosebud County, Montana, 1979. The origin of the name is from a Milwaukee Road (Chicago, Milwaukee, St. Paul, and Pacific Railroad Co.) siding.

REMARKS: Soil interpretations record: MT0547. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (mixed) (A, Bw, part of Bz1 horizons); horizons of salt accumulation from 6 to 15 inches (Bz1, Bz2 horizons); a particle-size control section from 10 to 40 inches (Bz1, Bz2, BC horizons). Antwerp soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.


National Cooperative Soil Survey
U.S.A.