LOCATION GILBOA IN

Established Series
Rev. JRB-WDH-TJE
11/2021

GILBOA SERIES

The Gilboa series consists of very deep, somewhat poorly drained soils that formed in as much as 51 cm (20 inches) of loess or other silty material and in the underlying loamy outwash and till. Gilboa soils are on ground moraines and end moraines. Slope ranges from 0 to 4 percent. Mean annual precipitation is about 940 mm (37 inches), and mean annual temperature is about 10.6 degrees C (51 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aquic Argiudolls

TYPICAL PEDON: Gilboa silt loam, on a northwest-facing, convex, 1 percent slope in a cultivated field. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 23 cm (9 inches); very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; weak fine subangular blocky structure parting to weak fine granular; friable; common very fine roots; moderately acid: abrupt smooth boundary.

A--23 to 28 cm (9 to 11 inches); very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate medium subangular blocky structure; friable; few very fine roots; moderately acid; clear wavy boundary. [Combined thickness of the A horizon is 25 to 51 cm (10 to 20 inches).]

Bt1--28 to 48 cm (11 to 19 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate fine subangular blocky structure; friable; few very fine roots; thin discontinuous dark grayish brown (10YR 4/2) clay films on faces of peds; common very dark grayish brown (10YR 3/2) fillings in old root channels; common fine distinct grayish brown (10YR 5/2) iron depletions; 1 percent gravel; moderately acid; clear wavy boundary. [0 to 25 cm (10 inches) thick]

2Bt2--48 to 74 cm (19 to 29 inches); yellowish brown (10YR 5/6) loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; few very fine roots; thin continuous dark grayish brown (10YR 4/2) clay films on faces of peds; common very dark grayish brown (10YR 3/2) fillings in old root channels; many medium prominent grayish brown (10YR 5/2) iron depletions; 7 percent gravel; moderately acid; gradual wavy boundary.

2Bt3--74 to 99 cm (29 to 39 inches); yellowish brown (10YR 5/6) loam; moderate medium subangular blocky structure; friable; few very fine roots; thin continuous dark grayish brown (10YR 4/2) clay films on faces of peds; common very dark grayish brown (10YR 3/2) masses of organic material; common fine distinct strong brown (7.5YR 5/8) masses of oxidized iron; many medium prominent grayish brown (10YR 5/2) iron depletions; 3 percent gravel; neutral; abrupt wavy boundary. [Combined thickness of the Bt horizon is 51 to 96 cm (20 to 38 inches).]

3Bt4--99 to 114 cm (39 to 45 inches); light olive brown (2.5Y 5/4) loam; weak medium subangular blocky structure; firm; few very fine roots; thin discontinuous grayish brown (2.5Y 5/2) clay films on faces of peds; few light gray (10YR 7/1) carbonate masses; many fine prominent yellowish brown (10YR 5/8) masses of oxidized iron; many medium distinct light brownish gray (2.5Y 6/2) iron depletions; 5 percent gravel; slightly effervescent; moderately alkaline; gradual wavy boundary. [15 to 30 cm (6 to 12 inches) thick]

3C--114 to 152 cm (45 to 60 inches); light olive brown (2.5Y 5/4) loam; massive; firm; thin discontinuous grayish brown (2.5Y 5/2) clay films on faces of vertical cracks; common light gray (10YR 7/1) carbonate masses; few prominent yellowish red (5YR 5/6) and common fine distinct yellowish brown (10YR 5/6) masses of oxidized iron; common fine distinct grayish brown (2.5Y 5/2) iron depletions; 2 percent gravel; strongly effervescent; moderately alkaline.

TYPE LOCATION: Benton County, Indiana; about 5 miles south of Fowler; 700 feet east and 850 feet north of the southwest corner of sec. 4, T. 24 N., R. 8 W.

RANGE IN CHARACTERISTICS:
Thickness of the solum: 102 to 152 cm (40 to 60 inches)
Particle-size control section: averages 25 to 30 percent clay

Ap or A horizon:
Hue: 10YR
Value: 2 or 3
Chroma: 1 or 2
Texture: silt loam
Reaction: moderately acid to neutral

Bt horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 2 to 6
Rock fragment content: 0 to 5 percent
Reaction: moderately acid to neutral

2Bt horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 2 to 6
Texture: loam or clay loam
Rock fragment content: 3 to 14 percent
Reaction: moderately acid to neutral

3Bt horizon:
Hue: 10YR or 2.5Y
Value: 5 or 6
Chroma: 2 to 4
Texture: loam
Rock fragment content: 0 to 10 percent
Calcium carbonate equivalent: 0 to 25 percent
Reaction: neutral or slightly alkaline

3C horizon:
Hue: 10YR or 2.5Y
Value: 5 or 6
Chroma: 1 to 6
Texture: loam or fine sandy loam
Clay content: 15 to 22 percent
Rock fragment content: 0 to 10 percent
Calcium carbonate equivalent: 15 to 40 percent
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: These are the Andres, Aztalan, Darroch, Francesville, Houstenader, La Hogue, Lahoguess, Le Sueur, Marcellon, Newhaven, Odell, and Protivin series. Andres, Aztalan, and Protivin soils have more than 22 percent clay in the lower part of the series control section. Darroch soils have strata of sandy material in the lower part of the series control section. Francesville and Odell have a densic contact within the series control section. Houstenader soils have more than 14 percent rock fragments in the lower part of the argillic horizon. La Hogue soils do not have carbonates within a depth of 152 cm (60 inches). Lahoguess soils are sand or loamy sand in the lower part of the series control section. Le Sueur soils do not have a 2Bt horizon in loamy outwash and are in drier and cooler climates. Marcellon soils are less than 102 cm (40 inches) to the base of the sola. Newhaven soils are deeper than 152 cm (60 inches) to the base of the sola.

GEOGRAPHIC SETTING: Gilboa soils are on ground moraines and end moraines. Slope ranges from 0 to 4 percent. The soils formed in as much as 51 cm (20 inches) of loess or other silty material and in the underlying loamy outwash and till. Mean annual precipitation ranges from 864 to 1016 mm (34 to 40 inches). Mean annual temperature ranges from 10.0 to 11.1 degrees C (50 to 52 degrees F). Frost-free period is 150 to 185 days. Elevation is 143 to 277 meters (470 to 910 feet) above mean sea level.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Darroch and Odell soils and the Barce, Chalmers, Corwin, Drummer, Milford, and Selma soils. The Darroch soils are underlain by stratified sediments. The Odell soils and the moderately well drained Corwin soils are formed in till. The moderately well drained Barce soils are on slightly higher positions. The poorly drained Chalmers, Drummer, Milford, and Selma soils are in depressions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. The potential for surface runoff is very low or low. Saturated hydraulic conductivity is moderately high in the solum and low in the substratum. Permeability is moderate in the loess or other silty material and in the loamy outwash, moderately slow in the lower part of the solum in till, and slow or very slow in till substratum.

USE AND VEGETATION: Most areas of the soil are cropped to corn, soybeans, small grain, and legume hay. A few areas are used for pasture. Native vegetation is tall prairie grasses, chiefly big bluestem.

DISTRIBUTION AND EXTENT: MLRAs 110, 111C, and 111D in west-central and northwestern Indiana. The type location is in MLRA 111D. The series is of moderate extent.

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

SERIES ESTABLISHED: Benton County, Indiana, 1985.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: from the surface to a depth of 28 cm (Ap, A horizons).
Argillic horizon: from a depth of 28 to 114 cm (Bt, 2Bt, 3Bt horizons).
Aquic conditions: iron depletions in all horizons below a depth of 28 cm.

ADDITIONAL DATA: Lab data is available for this pedon (S83IN-007-010) at the National Soil Survey Laboratory, Lincoln, NE.

National Cooperative Soil Survey
U.S.A.