LOCATION IONA IN+ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Hapludalfs
TYPICAL PEDON: Iona silt loam on a nearly level slope of 1 percent in a cultivated field at an elevation of about 142 meters (465 feet) above mean sea level (MSL). (Colors are for moist soil.)
Ap--0 to 25 cm (0 to 10 inches); dark grayish brown (10YR 4/2) silt loam; light brownish gray (10YR 6/2) dry; weak medium granular structure; friable; many fine roots; slightly acid; abrupt smooth boundary. [18 to 28 cm (7 to 11 inches) thick]
Bt1--25 to 58 cm (10 to 23 inches); yellowish brown (10YR 5/4) silty clay loam; moderate medium subangular blocky structure; firm; common fine roots; many distinct brown (10YR 5/3) clay films on faces of peds; light gray (10YR 7/2) silt coatings in voids and faces of peds; strongly acid; clear wavy boundary.
Bt2--58 to 81 cm (23 to 32 inches); yellowish brown (10YR 5/4) silty clay loam; moderate medium and coarse subangular blocky structure; firm; few to common fine roots; many distinct brown (10YR 4/3) clay films on faces of peds; common fine distinct grayish brown (10YR 5/2) iron depletions and yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; few to common masses of iron and manganese accumulation; moderately acid; clear wavy boundary. [Combined thickness of Bt horizon ranges from 46 to 97 cm (18 to 38 inches.)]
BCt--81 to 114 cm (32 to 45 inches); light yellowish brown (10YR 6/4) silt loam; weak coarse subangular blocky structure; friable; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds; common fine distinct grayish brown (10YR 5/2) iron depletions and yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; common masses and stains of iron and manganese accumulation on faces of peds and pores; neutral; gradual wavy boundary. [0 to 41 cm (0 to 16 inches) thick]
C--114 to 152 cm (45 to 60 inches); light yellowish brown (10YR 6/4) silt loam; massive; friable; common coarse distinct light brownish gray (10YR 6/2) iron depletions; strongly effervescent; moderately alkaline.
TYPE LOCATION: Knox County, Indiana, about 3 miles northeast of Vincennes along State Highway 67; 1,350 feet southwest of the east corner and 200 feet northwest of the southeast boundary of donation 180; T. 4 N., R. 9 W.; USGS Frichton, IN-IL topographic quadrangle, lat. 38 degrees 43 minutes 45 seconds N., 087 degrees, 27 minutes, 31 seconds W., NAD 27, UTM 460131 easting and 4286838 northing, NAD 83.
RANGE IN CHARACTERISTICS:
Dpth to the base of the argillic horizon: 76 to 127 cm (30 to 50 inches)
Depth to carbonates: 102 to 152 cm (40 to 60 inches)
Sand content averages: less than 10 percent throughout the series control section
Ap horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 2 to 4
Reaction: neutral to strongly acid
A horizon, in undisturbed areas:
Depth: 2 to 4 inches thick
Hue: 10YR
Value: 3 or 4
Chroma: 1 or 2
Reaction: neutral to strongly acid.
Bt and BCt horizons:
Hue: 10YR
Value: 4 to 6
Chroma: 3 to 6
Texture: silty clay loam or silt loam
Reaction: slightly acid to strongly acid and ranges to neutral in the lower part
C horizon
Hue: 10YR
Value: 5 or 6
Chroma: 2 to 6
Reaction: slightly alkaline or moderately alkaline
Calcium carbonate equivalent: 5 to 30 percent
COMPETING SERIES: These are the Baraboo, Birkbeck, Cadiz, Campton, Elco, Eleroy, Homen, Inton, Libre, Mayville, Minnith, Morningsun, Redbud, Rocheport, Rockfield, Somonauk, Uniontown, Winfield, and Zurich series. Baraboo, Eleroy, and Rocheport soils have a lithic or paralithic contact at the base of the series control section. Birkbeck, Cadiz, Campton, Elco, Homen, Libre, Mayville, Minnith, Morningsun, Rockfield, Somonauk and Zurich soils have more than 10 percent sand in some subhorizon in the series control section. Libre soils have the base of the argillic at a depth of more than 203 cm (80 inches). Inton soils have hue yellower than 10YR above a depth of 76 cm (30 inches). Redbud soils average more than 30 percent clay in the lower part of the series control section. Uniontown soils formed in alluvium on low terraces and typically have yellower hue (2.5Y) and chroma of 2 or less in the substratum. Winfield soils do not have carbonates above a depth of 152 cm (60 inches).
GEOGRAPHIC SETTING: Iona soils are on nearly level or gently rolling loess hills. Slope gradients are commonly 0 to 4 percent and range to 6 percent. The soils formed in silty calcareous loess. The mean annual air temperature ranges from about 11 to 14 degrees C (52 to 57 degrees F), mean annual precipitation ranges from about 1016 to 1143 mm (40 to 45 inches), frost free period ranges from 170 to 210 days, and elevation ranges from 110 to 259 meters (360 to 850 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Sylvan, Reesville, and Ragsdale soils. The Sylvan soils are well drained, do not have redoximorphic depletions and are typically on steeper sideslopes. Reesville soils are somewhat poorly drained and are typically are on broad flats. Ragsdale soils have mollic epipedons, are very poorly drained, and are in depressions.
DRAINAGE AND PERMEABILITY: Moderately well drained. Depth to an intermittent apparent high water table is 61 to 102 centimeters (2 to 3.5 feet) from December to April in normal years. The potential for surface water runoff is low or medium. Saturated hydraulic conductivity is moderately high (1.41 to 4.23 micrometers/sec) in the subsoil. Permeability is moderately slow (0.2 to 0.6 inches per hour).
USE AND VEGETATION: Soils are mostly cultivated. Principal crops are corn, soybeans, wheat, and legume grass mixtures. Native vegetation is deciduous forest of maple, tulip-poplar, oaks, and hickory.
DISTRIBUTION AND EXTENT: Southwestern Indiana and southeastern Illinois. The series is of moderate extent in MLRAs 114B and 115A. The type location is in MLRA 115A.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Pike County, Indiana, 1930.
REMARKS: Diagnostic horizons and features recognized in this pedon are: 1) Ochric epipedon: the zone from the surface of the soil to a depth of 25 cm (10 inches); 2) Argillic horizon: the zone from about 25 to 81 cm (10 to 32 inches); 3) Redoximorphic features at 58 to 152 cm (23 to 60 inches).
ADDITIONAL DATA: Lab data available: Purdue; S812N125-10 and NSSL, S55ZN083-1