LOCATION RAPATEE ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, mesic Mollic Udarents
TYPICAL PEDON: Rapatee silty clay loam - on a southwest facing convex slope of 2 percent in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 3 inches; mixed black (10YR 2/1) and very dark gray (10YR 3/1) silty clay loam, dark gray (10YR 4/1) and gray (10YR 5/1) dry; moderate very fine subangular blocky structure; friable; common fine and very fine roots; some mixing and horizontal strata of yellowish brown (10YR 5/4 and 5/8) and grayish brown (10YR 5/2) material; about 2 percent sand; slightly acid; clear smooth boundary. (0 to 6 inches thick).
C1--3 to 18 inches; mixed, black (10YR 2/1) and very dark gray (10YR 3/1) silty clay loam, dark gray (10YR 4/1) and gray (10YR 5/1) dry; massive; firm; common fine roots; few moderate medium and coarse clods or soil fragments; some mixing and horizontal strata of yellowish brown (10YR 5/4 and 5/8) and grayish brown (10YR 5/2) material; few distinct dark stains and few fine rounded black concretions (iron and manganese oxides); about 2 percent sand; slightly acid; abrupt wavy boundary. (6 to 24 inches thick)
C2--18 to 48 inches; mixed dark yellowish brown (10YR 4/4) and yellowish brown (10YR 5/4) silty clay loam; massive; very dense, very firm; few weak coarse clods or soil fragments; few pockets of dark olive gray (5Y 3/2) silty clay loam; common fine rounded black concretions (iron and manganese oxides); about 8 percent sand; slightly alkaline; abrupt wavy boundary. (0 to 50 inches thick)
C3--48 to 60 inches; mixed brown (10YR 4/3), yellowish brown (10YR 5/4 and 5/6), and greenish gray (5G 5/1) clay loam; massive; extremely dense, very firm; few weak medium and coarse clods or soil fragments; common distinct dark stains and common fine black concretions (iron and manganese oxides); about 14 percent sand; common fragments of coal and shale; common dolomitic till pebbles; strong effervescence; slightly alkaline.
TYPE LOCATION: Knox County, Illinois; about 1 mile northwest of Victoria; 1,460 feet west and 2,300 feet north of the southeast corner of sec. 11, T. 12 N., R. 3 E.
RANGE IN CHARACTERISTICS: The particle-size control section averages between 22 and 35 percent clay and contains 0 to 20 percent by volume of rock fragments. The rock fragments commonly range from 2 mm to 15 cm (less than 1/8 inch to 6 inches) in diameter, but include some stones as large as 10 inches in diameter. Soil fragments and isolated peds of relict genetic horizons of pre-mined soils are randomly distributed throughout, and are disordered relative to any plane in the profile. The soil fragments have identifiable properties such as mottles, clay films, or coatings that are characteristic of their previous formation. The organic carbon content decreases irregularly with depth in most pedons because of mixing or layering, and because of the presence of coal or other carbonaceous material. These soils have a succession of compressed layers or traffic pans that formed during placement and grading of the soil material. These layers have moist bulk density of 1.6 g/cc or greater. The available water capacity is reduced because of the compaction and is low in individual layers. Boundaries between layers range from abrupt to gradual and from smooth to wavy, depending upon the method of reclamation used. Typically, roots are few to common throughout the upper part of the soil to a depth of about 48 inches, but generally are lacking below that depth. Some pedons have free carbonates throughout the C2 horizon.
The Ap and C1 horizons that formed in replaced darkened surface layers of pre-mined soils dominantly have hue of 10YR, value of 2 or 3, (4 or 5 dry) and chroma of 1 to 3. Some strata, included peds, and soil fragments have colors in the range defined for the C2 horizon. The Ap and C1 horizons are silt loam or silty clay loam. The Ap horizon has weak or moderate very fine or fine subangular blocky or granular structure. The Ap and C1 horizons range from friable to very firm. They are slightly acid or neutral.
The C horizon beneath the replaced darkened surface layer has hue of 10YR, 2.5Y, 5Y, 5G, 5GY, or 5BG; value of 4 to 6; and chroma of 1 to 8. Colors are mixed throughout. To a depth of about 48 inches the C horizon typically is silt loam or silty clay loam. The content of rock fragments 3 to 10 inches in diameter ranges 0 to 10 percent by volume. Below a depth of 48 inches the C horizon typically is loam, clay loam, silt loam, or silty clay loam or their channery or gravelly analogs. Rock fragment content ranges from 10 to 30 percent by volume. The C horizon is massive and is firm or very firm.
COMPETING SERIES: There are no other series in the same family. Soils in closely related families are the
Barkcamp,
Bethesda,
Enoch,
Fairpoint,
Harvester,
Lenzburg,
Morristown,
Strahan, and
Swanwick series.
Barkcamp, Bethesda, Enoch, Fairpoint, and Morristown soils contain more than 35 percent rock fragments in the control section. In addition, Barkcamp, Bethesda, and Enoch soils are acid, and Morristown soils are calcareous.
Harvester soils were disturbed only to a depth of about 40 inches and do not have coarse fragments throughout.
Lenzburg soils are fine-loamy and calcareous, and typically contain more coarse fragments in the control section.
Strahan soils have a regular decrease in organic carbon with increasing depth, are more friable, and more permeable, having formed in leached undisturbed loess.
Swanwick soils do not have colors with value of 2 or 3 throughout much of Ap and C1 horizons.
GEOGRAPHIC SETTING: Rapatee soils are on nearly level to strongly sloping ridgetops and sideslopes of reconstructed landscapes. Slope gradients range from 1 to 15 percent. These soils formed in materials that were excavated and reclaimed during surface mining operations. The upper 48 inches of regolith is dominantly fine-earth material that has the darkened surface layers of pre-mined soils returned to the surface. The underlying regolith below a depth of about 48 inches is a mixture of unconsolidated fine-earth material and fragments of bedrock. Rock fragments are commonly soft shale and siltstone, with some sandstone and limestone included. Mean annual temperature varies from 48 to 54 degrees F, and mean annual precipitation varies from 32 to 36 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lenzburg soils in areas that have been excavated during mining and the Ipava, Sable, and Tama soils on adjacent unmined landscapes. Lenzburg soils are nearby; graded areas are on similar parts of the landscape, and ungraded areas are steeper or on narrow parallel ridges. Lenzburg soils have not had the darkened surface layers returned to the surface after mining. Ipava, Sable, and Tama soils formed in loess and contain B horizons.
DRAINAGE AND PERMEABILITY: Well drained. The potential for surface runoff is low to very high. Permeability is moderately slow in the surface layer, is moderately slow and very slow in the substratum to a depth of about 48 inches, and is very slow in the lower part of the substratum. Water perches at various levels within the soil on the compressed layers, but primarily on the discontinuity at a depth of about 48 inches.
USE AND VEGETATION: Rapatee soils are used for cultivated crops. Corn, soybeans, and small grain are the principal crops. Some areas are seeded to grass-legume mixtures for pasture or hay.
DISTRIBUTION AND EXTENT: West central Illinois, mainly in MLRA 108. The extent is small. Their extent will increase as surface mining operations continue.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Knox County, Illinois, 1983.
REMARKS: The dark colors in the Ap and C1 horizons of these soils result from replacement of the darkened surface layers of pre-mined soils.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 3 inches.
ADDITIONAL DATA: Data for several pedons in Illinois have been collected and are on file at the NRCS state office in Champaign, Illinois.