LOCATION REDBUD IL
Established Series
Rev. WMM-RAL
07/2011
REDBUD SERIES
The Redbud series consists of very deep, moderately well drained soils on loess-covered lacustrine terraces. Redbud soils formed in loess and the underlying lacustrine deposits. Slope ranges from 2 to 18 percent. Mean annual precipitation is about 965 mm (38 inches), and mean annual temperature is about 13 degrees C (55 degrees F).
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Hapludalfs
TYPICAL PEDON: Redbud silt loam, in a cultivated field on a lacustrine terrace tread at an elevation of about 128 meters (420 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 22 cm (0 to 9 inches); brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; moderate fine granular structure; friable; common very fine and fine roots throughout; neutral; abrupt smooth boundary. [15 to 25 cm (6 to 10 inches) thick]
E--22 to 41 cm (9 to 16 inches); dark yellowish brown (10YR 4/4) silt loam, pale brown (10YR 6/3) dry; moderate medium platy structure; friable; common very fine roots throughout; few distinct dark brown (10YR 3/3) organic coatings lining root channels; few fine irregular black (N 2.5/) iron-manganese masses; slightly acid; abrupt smooth boundary. [0 to 25 cm (10 inches) thick]
Bt1--41 to 56 cm (16 to 22 inches); strong brown (7.5YR 5/6) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; common very fine roots between peds; common distinct brown (7.5YR 4/2) clay films on faces of peds; few fine and medium irregular black (7.5YR 2.5/1) iron-manganese masses; moderately acid; clear smooth boundary.
Bt2--56 to 71 cm (22 to 28 inches); strong brown (7.5YR 5/6) silty clay loam; moderate medium prismatic structure parting to strong medium subangular blocky; firm; few very fine roots between peds; few prominent black (10YR 2/1) iron-manganese stains on faces of peds; common distinct brown (7.5YR 4/2) clay films on faces of peds; common fine and medium irregular black (7.5YR 2.5/1) iron-manganese masses; moderately acid; clear smooth boundary.
Bt3--71 to 91 cm (28 to 36 inches); strong brown (7.5YR 5/6) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; few very fine roots between peds; few prominent black (10YR 2/1) iron-manganese stains on faces of peds; common prominent brown (7.5YR 4/2) clay films on faces of peds; many medium prominent grayish brown (10YR 5/2) iron depletions and common medium faint yellowish red (5YR 5/6) masses of oxidized iron in the matrix; common fine and medium irregular black (7.5YR 2.5/1) iron-manganese masses; moderately acid; clear smooth boundary.
Bt4--91 to 114 cm (36 to 45 inches); brown (7.5YR 4/4) silty clay loam; moderate medium prismatic structure; friable; few very fine roots between peds; few distinct brown (7.5YR 4/2) clay films on faces of peds; common medium prominent grayish brown (10YR 5/2) iron depletions and common medium prominent yellowish red (5YR 5/6) masses of oxidized iron in the matrix; common fine and medium irregular black (7.5YR 2.5/1) iron-manganese masses; moderately acid; abrupt smooth boundary. [Combined thickness of the Bt horizon is 61 to 127 cm (24 to 50 inches).]
2Bt5--114 to 152 cm (45 to 60 inches); dark yellowish brown (10YR 4/4) silty clay; moderate medium prismatic structure; very firm; few very fine roots between peds; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds; many medium distinct grayish brown (10YR 5/2) iron depletions and common medium prominent strong brown (7.5YR 5/6) masses of oxidized iron in the matrix; common fine and medium irregular black (7.5YR 2.5/1) of iron-manganese masses; slightly acid; clear smooth boundary.
2Bt6--152 to 183 cm (60 to 72 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium prismatic structure; firm; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds; many medium distinct grayish brown (10YR 5/2) iron depletions and common medium prominent strong brown (7.5YR 5/6) masses of oxidized iron in the matrix; common fine and medium irregular black (7.5YR 2.5/1) of iron-manganese masses; slightly acid; clear smooth boundary. [Combined thickness of the 2Bt horizon is 61 to 122 cm (24 to 48 inches).]
2BCt--183 to 203 cm (72 to 80 inches); brown (10YR 4/3) silt loam; weak medium prismatic structure; friable; few distinct dark gray (10YR 4/1) clay films in root channels and pores; common coarse faint grayish brown (10YR 5/2) iron depletions in the matrix; few fine irregular black (7.5YR 2.5/1) of iron-manganese masses; neutral.
TYPE LOCATION: St. Clair County, Illinois; about 6 miles south of New Athens; approximately 1,280 feet north and 2,040 feet east of the southwest corner of sec. 28, T. 3 S., R. 7W.; USGS Red Bud, IL topographic quadrangle; lat. 38 degrees 14 minutes 10 seconds N. and long. 89 degrees 53 minutes 05 seconds W.
RANGE IN CHARACTERISTICS:
Depth to the base of the argillic horizon: 137 to more than 203 cm (54 to more than 80 inches)
Depth to carbonates: greater than 122 cm (48 inches) where present
Thickness of the loess: 91 to 178 cm (36 to 70 inches)
Particle-size control section: averages 27 to 35 percent clay and less than 7 percent sand
Ap horizon:
Hue: 10YR
Value: 4 or 5, 6 or 7 dry
Chroma: 2 or 3
Clay content: 12 to 25 percent
Sand content: less than 7 percent
Reaction: strongly acid to neutral, depending on liming history
A horizon, where present:
Value: 3
Chroma: 1 or 2
E horizon:
Hue: 10YR
Value: 4 to 6, 6 to 8 dry
Chroma: 3 to 6
Texture: silt loam or silty clay loam
Clay content: 12 to 32 percent
Sand content: less than 7 percent
Reaction: strongly acid to slightly acid, pedons that have been limed range to neutral
Some pedons have a BE or EB horizon.
Bt horizon:
Hue: 7.5YR to 2.5Y
Value: 4 to 6
Chroma: 2 or 6
Texture: silty clay loam or silt loam
Clay content: 22 to 35 percent
Reaction: very strongly acid to slightly acid
2Bt horizon and 2BC or 2C horizon, where present:
Hue: 7.5YR to 5Y
Value: 4 to 7
Chroma: 2 to 4
Texture: clay, silty clay, silty clay loam, or silt loam, and can be stratified with these textures
Clay content: 24 to 55 percent, and at least some part has more than 35 percent
Sand content: less than 15 percent
Ped surfaces: some pedons have pressure faces or slickensides
Calcium carbonate equivalent: 0 to 5 percent
Reaction: very strongly acid to moderately alkaline
COMPETING SERIES: These are the
Baraboo,
Birkbeck,
Cadiz,
Campton,
Elco,
Eleroy,
Inton,
Iona,
Libre,
Mayville,
Minnith,
Morningsun,
Rocheport,
Rockfield,
Somonauk,
Uniontown,
Winfield, and
Zurich series. Baraboo soils have a lithic contact at 50 to 100 cm (20 to 40 inches). Birkbeck, Campton, Elco, Minnith, Morningsun, Rockfield, Somonauk, and Zurich soils contain more than 15 percent sand in the lower part of the series control section. Cadiz soils have rock fragments in the lower part of the series control section. Eleroy and Rocheport soils have a paralithic contact within a depth of 152 cm (60 inches). Iona, Mayville, and Uniontown soils are less than 137 cm (54 inches) to the base of the argillic horizon. Inton soils typically have gray iron depletions within a depth of 51 cm (20 inches). Libre soils have a dense layer (2Btd horizon) in the middle part of the argillic horizon. Winfield soils have overlapping soil properties within the series control section but do not have a lithologic discontinuity in the lower part of the series control section.
GEOGRAPHIC SETTING: Redbud soils are on loess-covered lacustrine terraces treads and risers. Slope ranges from 2 to 18 percent. These soils formed in 91 to about 152 cm (36 inches to about 60 inches) of loess (Peoria silt), and the underlying lacustrine deposits (Equality Formation). Mean annual precipitation ranges from 914 to 1016 mm (36 to 40 inches). Mean annual temperature is 12 to 14 degrees C (54 to 57 degrees F). Frost-free period is 170 to 200 days. Elevation is 104 to 131 mm (340 to 430 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Bartelso,
Floraville,
Lakaskia,
Millstadt, and
Wabash soils. The somewhat poorly drained Bartelso and Millstadt soils are on nearly level or gently sloping convex treads of lacustrine terraces. Also, Bartelso soils have a mollic epipedon. The poorly drained Floraville and Lakaskia soils are on nearly level or slightly depressional treads of lacustrine terraces. Also, the Lakaskia soils have a mollic epipedon. The poorly drained Floraville soils and the somewhat poorly drained Millstadt soils form a hydrosequence with the Redbud soils. The very poorly drained Wabash soils have a mollic epipedon and are in drainageways on lacustrine terraces.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. Depth to the top of an intermittent perched high water table ranges from 61 to 107cm (2.0 to 3.5 feet) between January and April in normal years. Potential for surface runoff is slow to rapid. Saturated hydraulic conductivity is moderately low. Permeability is slow.
USE AND VEGETATION: Most areas are cropped to corn, soybeans, and small grain. A few areas are pastured or wooded. Native vegetation is mixed hardwood forest.
DISTRIBUTION AND EXTENT: MLRAs 113 and 114B in southwestern and southern Illinois. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: St. Clair County, Illinois, 1995.
REMARKS: Redbud soils were formerly included with the terrace variants of the Muren and Alford series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from the surface to a depth of 41cm (16 inches) (Ap and E horizons).
Argillic horizon: from a depth of 41 to 183 cm (16 to 72 inches) (Bt1, Bt2, Bt3, Bt4, 2Bt5, and 2Bt6 horizons).
Aquic conditions: Iron depletions present from a depth of 28 to 80 inches (Bt3, Bt4, 2Bt5, 2Bt6, and 2BCt horizons).
ADDITIONAL DATA: See data from the St. Clair County Glacial Lake Kaskaskia Study, Part II (S93IL-163-016; NSSL pedon number: 94P-274-1731-1742).
National Cooperative Soil Survey
U.S.A.