LOCATION SOUTHWEST IN

Established Series
Rev. RAB-FF-TRZ
11/2021

SOUTHWEST SERIES

The Southwest series consists of very deep, poorly drained soils formed in recent alluvium over glaciofluvial deposits or glaciolacustrine deposits in depressions on till plains, moraines, and outwash plains. Slope ranges from 0 to 1 percent. Mean annual precipitation is about 914 mm (36 inches), and mean annual temperature is about 10.0 degrees C (50 degrees F).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, mesic Typic Fluvaquents

TYPICAL PEDON: Southwest silt loam, on a concave, 1 percent slope in a cultivated field at an elevation of 250 meters (820 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 25 cm (10 inches); dark grayish brown (10YR 4/2) silt loam; weak fine granular structure; friable; common very fine and fine roots throughout; slightly acid; clear wavy boundary. [10 to 46 cm (4 to 18 inches) thick]

Bg1--25 to 46 cm (10 to 18 inches); dark grayish brown (10YR 4/2) silty clay loam; weak medium subangular blocky structure; friable; common very fine and fine roots throughout; many fine and medium interstitial and tubular pores with moderate continuity; common medium faint brown (10YR 4/3) masses of oxidized iron in the matrix; slightly acid; clear wavy boundary.

Bg2--46 to 58 cm (18 to 23 inches); dark grayish brown (10YR 4/2) silty clay loam; weak medium subangular blocky structure; friable; common very fine and fine roots throughout; common fine and medium interstitial and tubular pores with moderate continuity; common medium faint brown (10YR 4/3) masses of oxidized iron in the matrix; slightly acid; clear wavy boundary. [Combined thickness of the Bg horizon is 15 to 56 cm (6 to 22 inches).]

2Ab--58 to 86 cm (23 to 34 inches); black (10YR 2/1) silty clay loam; moderate fine subangular blocky structure; firm; common very fine and fine roots throughout; neutral; clear wavy boundary. [15 to 30 cm (6 to 12 inches) thick]

2Bgb--86 to 114 cm (34 to 45 inches); gray (10YR 5/1) silty clay loam; moderate medium subangular blocky structure; firm; many medium distinct brown (10YR 5/3) and common fine prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; neutral; clear wavy boundary. [28 to 76 cm (11 to 30 inches) thick]

3Ab1--114 to 140 cm (45 to 55 inches); very dark grayish brown (10YR 3/2) silty clay loam; weak coarse subangular blocky structure; firm; common medium prominent dark yellowish brown (10YR 4/6) masses of oxidized iron in the matrix; neutral; gradual wavy boundary.

3Ab2--140 to 190 cm (55 to 75 inches); very dark grayish brown (10YR 3/2) silty clay loam; weak thick platy structure; friable; common medium prominent dark yellowish brown (10YR 4/6) masses of oxidized iron in the matrix; neutral; gradual wavy boundary. [Combined thickness of the 3Ab horizon is 0 to 76 cm (30 inches).]

3Cg--190 to 203 cm (75 to 80 inches); dark gray (5Y 4/1) silt loam; massive; friable; slightly effervescent; slightly alkaline.

TYPE LOCATION: Elkhart County, Indiana; about 3 miles north and 2 miles east of Wakarusa; 129 feet west and 1,167 feet south of the northeast corner of sec. 8, T. 36 N., R. 5 E.; USGS Foraker, IN topographic quadrangle; lat. 41 degrees 35 minutes 28 seconds N. and long. 85 degrees 57 minutes 53 seconds W., NAD 27; UTM Zone 16, 586286 easting and 4604903 northing, NAD 83.

RANGE IN CHARACTERISTICS:
Depth to carbonates: 102 to more than 203 cm (40 to more than 80 inches)
Thickness of the overwash and depth to a buried soil: 25 to 102 cm (10 to 40 inches)
Rock fragment content: 0 to 5 percent gravel below the overwash

Ap horizon:
Hue: 10YR
Value: 4
Chroma: 2 or 3
Texture: silt loam
Reaction: slightly acid or neutral

A horizon: (where present)
Hue: 10YR
Value: 3
Chroma: 2 or 3
Texture: silt loam
Reaction: slightly acid or neutral
Thickness: less than 7 inches

Bg horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 1 or 2
Texture: silt loam or silty clay loam
Reaction: slightly acid or neutral

2Ab, 2Bgb, or 3Ab horizon:
Hue: 10YR or 2.5Y
Value: 2 to 6
Chroma: 1 or 2
Texture: silty clay loam, silt loam, clay loam, or loam
Reaction: slightly acid to slightly alkaline

3Cg or 3C horizon: (where present)
Hue: 10YR to 5Y
Value: 4 or 5
Chroma: 1 to 4
Texture: loam, silt loam, or clay loam
Calcium carbonate equivalent: 5 to 25 percent
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: These are the Birds and Killbuck series. Birds soils do no have a buried soil (Ab) within a depth of 102 cm (40 inches). Killbuck soils are on flood plains and are subject to flooding.

GEOGRAPHIC SETTING: Southwest soils are in depressions on moraines, till plains, and outwash plains of Wisconsinan age. Slope ranges from 0 to 1 percent. Southwest soils formed in 25 to 102 cm (10 to 40 inches) of recent alluvium overlying glaciofluvial deposits or glaciolacustrine deposits. Mean annual precipitation ranges from 787 to 1067 mm (30 to 42 inches). Mean annual temperature ranges from 10.0 to 12.8 degrees C (50 to 55 degrees F). Frost-free period is 130 to 180 days. Elevation is 177 to 466 meters (580 to 1,530 feet) above mean sea level.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brookston, Crosier, Miami, Morley, Riddles, and Williamstown soils. All of these soils are formed in till. The poorly drained Brookston soils are in depressions on till plains. The somewhat poorly drained Crosier soils are on swells on till plains. The moderately well drained Miami, Morley, and Williamstown soils, and the well drained Riddles soils are on backslopes on swells and knolls surrounding depressions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. Depth to the top of a seasonal high water table ranges from 15 cm (0.5 foot) above the surface to 30 cm (1 foot) below the surface for some time in normal years. Potential for surface runoff is negligible to low. Saturated hydraulic conductivity is moderately high. Permeability is moderate in the recent alluvium and moderately slow in the buried soil.

USE AND VEGETATION: Soils are mostly used to grow corn, soybeans, oats, and wheat. A small part is in permanent pasture or woodlots. Native vegetation is deciduous forest and some swamp grasses and sedges.

DISTRIBUTION AND EXTENT: MLRAs 111A, 111B, 111C, and 111D in northern and central Indiana. The series is of small extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: AMHERST, MASSACHUSETTS

SERIES ESTABLISHED: Delaware County, Indiana, 1996.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from the surface to a depth of 25 cm (10 inches) (Ap).
Cambic horizon: from a depth of 25 to 58 cm (10 to 23 inches) (Bg1, Bg2).
Aquic conditions: redoximorphic features present in all horizon below a depth of 25 cm (10 inches) (Bg, 2Ab, 2Bgb, 3Ab, and 3Cg horizons).

Drained (IN0612) and undrained (IN0613) phases are recognized.

NASIS Data Mapunit ID 155046 represents the typical pedon in northern Indiana.

ADDITIONAL DATA: Lab characterization data is available for the typical pedon (S94IN-039-024) from the National Soil Survey Laboratory, Lincoln, NE. Transect data for the typical pedon (T94IN-039-141 is on file in the MLRA project office in Plymouth, Indiana. Transect shows 70 percent Southwest soils, 20 percent Brookston soils, and 10 percent Crosier soils.

National Cooperative Soil Survey
U.S.A.