LOCATION IONA IN+IL
Established Series
Rev. BGN-TJE
07/2011
IONA SERIES
The Iona series consists of very deep, moderately well drained soils formed in loess on loess hills. Slope ranges from 0 to 6 percent. Mean annual precipitation is about 1067 mm (42 inches), and mean annual temperature is about 12.8 degrees C (55 degrees F).
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Hapludalfs
TYPICAL PEDON: Iona silt loam, on a 1 percent slope in a cultivated field at an elevation of about 142 meters (465 feet) above mean sea level (Colors are for moist soil unless otherwise stated.)
Ap--0 to 25 cm (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 on 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; 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; common fine prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; common iron-manganese masses; moderately acid; clear wavy boundary. [Combined thickness of the Bt horizon is 46 to 96 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; common fine prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; common iron-manganese masses and stains on faces of peds and in pores; neutral; gradual wavy boundary. [0 to 41 cm (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. and 087 degrees 27 minutes 31 seconds W., NAD 27; UTM Zone 16, 460131 easting and 4286838 northing, NAD 83.
RANGE IN CHARACTERISTICS:
Depth 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: strongly acid to neutral
A horizon, where present:
Thickness: 5 to 10 cm (2 to 4 inches)
Hue: 10YR
Value: 3 or 4
Chroma: 1 or 2
Reaction: strongly acid to neutral
Bt and BCt horizons:
Hue: 10YR
Value: 4 to 6
Chroma: 3 to 6
Texture: silty clay loam or silt loam
Reaction: strongly acid to slightly acid and ranges to neutral in the lower part
C horizon
Hue: 10YR
Value: 5 or 6
Chroma: 2 to 6
Calcium carbonate equivalent: 5 to 30 percent
Reaction: slightly alkaline or moderately alkaline
COMPETING SERIES: These are the
Baraboo,
Birkbeck,
Cadiz,
Campton,
Elco,
Eleroy,
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 within a depth of 152 cm (60 inches). Birkbeck, Cadiz, Campton, Elco, Libre, Mayville, Minnith, Morningsun, Rockfield, Somonauk, and Zurich soils have more than 10 percent sand in some subhorizon in the series control section. Inton soils have hue yellower than 10YR in the lower part of the series control section. Redbud soils are deeper than 127 cm (50 inches) to the base of the argillic horizon. Uniontown soils compete closely with Iona soils on soil properties but are 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 within a depth of 152 cm (60 inches).
GEOGRAPHIC SETTING: Iona soils are on loess hills. Slope gradients are commonly 0 to 4 percent and range to 6 percent. The soils formed in loess. Mean annual precipitation ranges from 1016 to 1143 mm (40 to 45 inches). Mean annual temperature ranges from 11.1 to 13.9 degrees C (52 to 57 degrees F). Frost-free period is 170 to 210 days. Elevation is 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 and are typically on steeper sideslopes. Reesville soils are somewhat poorly drained and are typically are on broad flats. The poorly drained Ragsdale soils have mollic epipedons and are in depressions.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. Depth to an intermittent apparent high water table ranges from 61 to 102 cm (2 to 3.5 feet) between December and April in normal years. Potential for surface runoff is low or medium. Saturated hydraulic conductivity is moderately high. Permeability is moderately slow.
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: MLRAs 114B and 115A in southwestern Indiana and southeastern Illinois. The type location is in MLRA 115A. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Pike County, Indiana, 1930.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from the surface to a depth of 25 cm (10 inches) (Ap horizon).
Argillic horizon: from a depth of 25 to 81 cm (10 to 32 inches (Bt horizon).
Aquic conditions: redoximorphic features present in all horizons below a depth of 58 cm (23 inches).
ADDITIONAL DATA: Lab data available: Purdue; S812N125-10 and NSSL, S55ZN083-1.
National Cooperative Soil Survey
U.S.A.