LOCATION ROCKFIELD               IN

Established Series
Rev. RJB-BC-TJE
11/2021

ROCKFIELD SERIES

The Rockfield series consists of very deep, moderately well drained soils that are deep to dense till. The Rockfield soils formed in silty material and in the underlying loamy outwash and till. They are on terraces and till plains. Slope ranges from 0 to 6 percent. Mean annual precipitation is about 940 mm (37 inches), and mean annual air temperature is about 11 degrees C (51 degrees F).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Hapludalfs

TYPICAL PEDON: Rockfield silt loam, on a west-facing, convex 1 percent slope in a cultivated field at an elevation of 195 meters (640 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 25 cm (0 to 10 inches); brown (10YR 4/3) silt loam, very pale brown (10YR 7/3) dry; moderate medium granular structure; friable; common very fine and fine roots; slightly acid; abrupt smooth boundary. [18 to 25 cm (7 to 10 inches) thick]

BE--25 to 33 cm (10 to 13 inches); yellowish brown (10YR 5/4) silt loam; moderate fine subangular blocky structure; friable; common very fine and fine roots; thin continuous brown (10YR 4/3) organic coatings on faces of peds; slightly acid; clear smooth boundary. [0 to 8 cm (0 to 3 inches) thick]

Bt1--33 to 79 cm (13 to 31 inches); yellowish brown (10YR 5/6) silty clay loam; moderate fine subangular blocky structure; friable; few fine and very fine roots; thin continuous yellowish brown (10YR 5/4) clay films on faces of peds; very strongly acid; gradual wavy boundary. [36 to 81 cm (14 to 32 inches) thick]

2Bt2--79 to 91 cm (31 to 36 inches); yellowish brown (10YR 5/6) loam; moderate medium subangular blocky structure; friable; few very fine roots; thin continuous dark yellowish brown (10YR 4/6) clay films on faces of peds; 2 percent rock fragments; strongly acid; clear wavy boundary.

2Bt3--91 to 114 cm (36 to 45 inches); yellowish brown (10YR 5/4) loam; moderate medium subangular blocky structure; friable; thin continuous dark yellowish brown (10YR 4/6) clay films on faces of peds; common fine faint light yellowish brown (10YR 6/4) masses of iron accumulation; 3 percent rock fragments; moderately acid; clear wavy boundary.

2Bt4--114 to 127 cm (45 to 50 inches); yellowish brown (10YR 5/4) loam; moderate medium subangular blocky structure; friable; thin continuous dark yellowish brown (10YR 4/4) clay films on faces of peds; common fine distinct yellowish brown (10YR 5/6) masses of iron accumulation; few fine distinct light brownish gray (10YR 6/2) iron depletions; 2 percent rock fragments; neutral; clear wavy boundary. [Combined thickness of the 2Bt horizon is 38 to 76 cm (15 to 30 inches).]

3Bt5--127 to 142 cm (50 to 56 inches); light yellowish brown (10YR 6/4) loam; weak medium subangular blocky structure; firm; thin discontinuous dark yellowish brown (10YR 4/4) clay films on faces of peds; few fine distinct light brownish gray (10YR 6/2) iron depletions; 7 percent rock fragments; slightly effervescent; slightly alkaline; clear wavy boundary. [13 to 25 cm (5 to 10 inches) thick]

3Cd--142 to 152 cm (56 to 60 inches); light olive brown (2.5Y 5/4) loam; massive; firm; 5 percent rock fragments; strongly effervescent; moderately alkaline.

TYPE LOCATION: Warren County, Indiana; about 0.25 mile north of Green Hill; 800 feet east and 50 feet north of the southwest corner of sec. 21, T. 23 N., R. 6 W.; USGS Otterbein, Ind. topographic quadrangle; lat. 40 degrees 25 minutes 2.5 seconds N. and long. 87 degrees 6 minutes 33 seconds W., NAD 27; UTM Zone 16, 490738 easting and 4474090 northing, NAD 83.

RANGE IN CHARACTERISTICS:
Thickness of the silty material: 61 to 102 cm (24 to 40 inches)
Thickness of the solum: 127 to 152 cm (50 to 60 inches)
Depth to the 3Bt horizon: 114 to 140 cm (45 to 55 inches)
Depth to carbonates: 114 to 152 cm (45 to 60 inches)
Depth to densic contact: 127 to 152 cm (50 to 60 inches)
Depth to chroma 2 or less (iron depletions): 76 to 122 cm (30 to 48 inches)
Particle-size control section: averages 27 to 32 percent clay

Ap horizon:
Hue: 10YR
Value: 4
Chroma: 2 or 3; eroded pedons range to chroma 4
Texture: silt loam
Reaction: very strongly acid to neutral depending on liming history

Bt horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 4 to 6
Texture: silt loam or silty clay loam
Clay content: 20 to 32 percent
Reaction: very strongly acid to moderately acid

2Bt horizon:
Hue: 10YR or 7.5YR
Value: 4 or 5
Chroma: 4 to 6
Texture: clay loam, sandy clay loam, or loam
Clay content: 20 to 32 percent
Rock fragment content: 0 to 10 percent
Reaction: the upper part is strongly acid to slightly acid and the lower part is moderately acid to neutral

3Bt horizon:
Hue: 10YR or 2.5Y
Value: 5 or 6
Chroma: 4 to 6
Texture: loam
Clay content: 18 to 27 percent
Rock fragment content: 3 to 5 percent
Calcium carbonate equivalent: 0 to 25 percent
Reaction: neutral to moderately alkaline

3Cd horizon:
Hue: 10YR or 2.5Y
Value: 5
Chroma: 3 or 4
Texture:
Clay content: 12 to 20 percent
Rock fragment content: 3 to 5 percent
Moist bulk density: 1.70 to 2.00 g/cc
Calcium carbonate equivalent: 15 to 40 percent
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: These are the Baraboo, Birkbeck, Cadiz, Campton, Elco, Eleroy, Homen, Inton, Iona, Libre, Mayville, Minnith, Morningsun, Redbud, Rocheport, Somonauk, Uniontown, Winfield, and Zurich series. Baraboo, Eleroy, and Rocheport soils have a lithic or paralithic contact within a depth of 152 cm (60 inches). Birkbeck, Iona, Uniontown, and Winfield soils are deeper than 102 cm (40 inches) to horizons containing more than 20 percent sand. Cadiz, Campton, Morningsun, and Somonauk soils do not have a densic contact in the lower part of the series control section. Elco, Homen, Libre, and Minnith soils do no have carbonates within 152 cm (60 inches). Inton soils are less than 76 cm (30 inches) to redox depletions with chroma of 2 or less. Mayville and Zurich soils have carbonates within a depth of 114 cm (45 inches). Redbud soils have more than 20 percent clay in the lower part of the series control section.

GEOGRAPHIC SETTING: Rockfield soils are on terraces and till plains. Slope ranges from 0 to 6 percent. The soils formed in 61 to 102 cm (24 to 40 inches) of silty material and in the underlying loamy outwash and till. Mean annual precipitation ranges from 889 to 940 mm (35 to 37 inches). Mean annual air temperature ranges from 10 to 11 degrees C (50 to 52 degrees F).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cyclone, Fincastle, Miami, Rainsville, Starks, and Williamstown soils. The poorly drained Cyclone soils have a darker colored surface layer and are in depressions. The somewhat poorly drained Fincastle and Starks soils have redoximorphic features in the upper part of the subsoil and are on slightly lower lying landscape positions. Miami soils have thinner layers of silty material over till and typically are on more sloping areas in the landscape. Rainsville soils are on similar landscape positions and have more sand in the upper part of the solum. Williamstown soils have sola less than 102 cm (40 inches) thick and are on similar landscape positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. The depth to the top of an intermittent perched high water table is 46 to 91 cm (1.5 to 3.0 feet) between December and April in normal years. The potential for surface runoff is negligible to medium. Saturated hydraulic conductivity is moderately high in the solum and low or moderately low in the dense till substratum. Permeability is moderate in the silty and loamy sediments, moderately slow in the lower part of the solum formed in till, and slow or very slow in the dense till substratum.

USE AND VEGETATION: Most areas are cropped to corn, soybeans, small grain, and legume hay. A few areas are used for pasture. Native vegetation is mixed hardwoods of oak, hickory, and maple.

DISTRIBUTION AND EXTENT: West-central Indiana; MLRA 111D. The series is of moderate extent.

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

SERIES ESTABLISHED: Warren County, Indiana, 1987.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from the surface to a depth of 33 cm (Ap, BE horizons).
Argillic horizon: from a depth of 33 to 142 cm (Bt, 2Bt, 3Bt horizons).
Densic contact: at 142 cm (top of 3Cd horizon).

ADDITIONAL DATA: Characterization data is available for the typical pedon (85IN171-002) from the National Soil Survey Laboratory, Lincoln, NE.

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National Cooperative Soil Survey
U.S.A.