LOCATION IVA IN+IL MO OH

Established Series
Rev. LAK-GRS
03/2011

IVA SERIES

The Iva series consists of very deep, somewhat poorly drained soils formed in loess. These soils are on uplands and terraces and have slopes ranging from 0 to 6 percent. Mean annual temperature is about 13 degrees C (56 degrees F), and mean annual precipitation is about 1068 mm (42 inches).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aeric Endoaqualfs

TYPICAL PEDON: Iva silt loam - on a nearly level slope of about 2 percent gradient in a cultivated field at an elevation of about 195 meters (640 feet) above mean sea level (MSL). (Colors are for moist soil unless otherwise stated.)

Ap--0 to 20 cm (0 to 8 inches); dark grayish brown (10YR 4/2) silt loam; light brownish gray (10YR 6/2) dry; weak fine granular structure; friable; many fine roots; slightly acid; abrupt smooth boundary. [15 to 25 cm (6 to 10 inches) thick]

E--20 to 30 cm (8 to 12 inches); grayish brown (10YR 5/2) silt loam; weak thick platy structure; friable; many fine roots; common fine distinct yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; strongly acid; clear wavy boundary. [0 to 15 cm (0 to 6 inches) thick]

BE--30 to 38 cm (12 to 15 inches); grayish brown (10YR 5/2) silt loam; moderate fine subangular blocky structure; friable; common fine roots; many distinct light gray (10YR 7/2) clay depletions on faces of peds; common fine distinct yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; very strongly acid; clear wavy boundary. [0 to 20 cm (0 to 8 inches) thick]

Bt1--38 to 76 cm (15 to 30 inches); yellowish brown (10YR 5/4) silty clay loam; moderate medium subangular blocky structure; firm; many distinct grayish brown (10YR 5/2) clay films on faces of peds; common distinct light gray (10YR 7/2) clay depletions on faces of peds; common medium distinct light brownish gray (10YR 6/2) iron depletions in the matrix; few fine distinct black (10YR 2/1) iron-manganese concretions; very strongly acid; clear wavy boundary.

Bt2--76 to 104 cm (30 to 41 inches); yellowish brown (10YR 5/6) silty clay loam; moderate medium and coarse subangular blocky structure; firm; many distinct grayish brown (10YR 5/2) clay films on faces of peds; many medium prominent light brownish gray (10YR 6/2) iron depletions in the matrix; few fine prominent black (10YR 2/1) iron-manganese concretions; strongly acid; gradual wavy boundary. [Combined thickness of the B2t horizon is 51 to 102 cm (20 to 40 inches)].

BCt--104 to 137 cm (41 to 54 inches); yellowish brown (10YR 5/4) silt loam; weak coarse subangular blocky structure; friable; common distinct grayish brown (10YR 5/2) clay films on faces of peds; few distinct light gray (10YR 7/2) silt coatings along vertical faces of peds; many coarse distinct light brownish gray (10YR 6/2) iron depletions in the matrix; few fine distinct black (10YR 2/1) iron-manganese concretions; slightly acid; gradual wavy boundary.[ 0 to 51 cm (0 to 20 inches) thick]

C--137 to 152 cm (54 to 60 inches); mottled yellowish brown (10YR 5/4) and light brownish gray (10YR 6/2) silt loam; massive; friable; few fine distinct black (10YR 2/1) iron-manganese concretions; slightly acid.

TYPE LOCATION: Knox County, Indiana; about 2 miles southeast of Freelandville; 1330 feet west and 1300 feet south of the NE corner, of sec. 23, T. 5 N., R. 8 W.; USGS Plainville topographic quadrangle; lat 38 degrees 51 minutes 34.167 seconds N. and 087 degrees 09 minutes 10.042 seconds W., UTM Zone 16, 486734 easting and 4301183 northing, NAD 83.

RANGE IN CHARACTERISTICS:
Depth to the top of the argillic horizon: less than 61 cm (24 inches)
Depth to the base of the argillic horizon: 102 to 152 cm (40 to 60 inches)
Depth to carbonates: more than 203 cm (80 inches)
Mean annual soil temperature: 13.3 to 15 degrees C. (56 to slightly less than 59 degrees F.)

Ap horizon:
Hue: 10YR
Value: 4 or 6
Chroma: 2 or 3
Texture: silt loam or silt
Clay content: 10 to 18 percent
Sand content: 3 to 12 percent
Reaction: strongly acid to neutral

E and BE horizons, where present:
Hue: 10YR
Value: 5 or 6
Chroma: 2 or 3
Texture: silt loam
Clay content: 12 to 20 percent
Sand content: 3 to 12 percent
Reaction: very strongly acid to neutral

Bt and BCt horizons:
Hue: 10YR
Value: 5
Chroma: 3 to 6, and is distinctly mottled
Texture: silty clay loam or silt loam
Clay content: 22 to 32 percent
Sand content: 3 to 10 percent
Reaction: very strongly acid to slightly acid

C horizon:
Hue: 10YR
Value: 5 or 6
Chroma: 2 to 6
Texture: silt loam or silt
Clay content: 10 to 20 percent
Sand content: 3 to 15 percent
Reaction: strongly acid to neutral

COMPETING SERIES: These are the Aptakisic, Caseyville, Creal, Fitchville, Kendall, Starks, Stronghurst, Waynetown, and Yeddo series. Aptakisic soils have sola less than 102 cm (40 inches) thick. Caseyville soils have less than 7 percent sand throughout the subsoil and substratum and contain more smectitic clay and less illitic clay. Creal soils are 24 inches or more to the top of the argillic horizon. Fitchville soils have bedding plane stratification or lamination within the series control section and have a mean annual soil temperature less than 13.3 degrees C. (56 degrees F). Kendall and Starks soils contain more than 15 percent sand in the lower part of the soil profile. Stronghurst soils have a mean annual soil temperature less than 13.3 degrees C. (56 degrees F.), contain more smectitic clay and less illitic clay and inherently contain more phosphate and potash. Waynetown soils have more than 15 percent rock fragments in the lower part of the soil profile. Yeddo soils have carbonates within a depth of 140 cm (55 inches).

GEOGRAPHIC SETTING: Iva soils are on nearly level to gently sloping topography on uplands and terrace. Slope gradients commonly are about 0 to 6 percent. Iva soils formed in 1.5 to more than 4 meters (5 to more than 12 feet) of loess on Illinoian till, or older landscapes overlying till, limestone, sandstone, siltstone, shale or outwash. The mean annual temperature varies from 12 to 14 degrees C (53 degrees to 57 degrees F) and the mean annual precipitation varies from 1016 to 1143 mm (40 to 45 inches). The mean annual soil temperature ranges from 13.3 to 15 degrees C. (56 to slightly less than 59 degrees F.).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alford, Muren, Hosmer, Ragsdale and Reesville soils. The well drained Alford soils, the moderately well drained Muren soils and the very poorly drained Ragsdale soils are in a drainage sequence with the Iva soils. Hosmer soils contain a fragipan, have browner sola and are on higher topographic positions. Reesville soils are on similar topographic positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. The depth to an intermittent apparent high water table is 15 to 61 cm (0.5 foot to 2.0 feet) from December to April in normal years. The potential for surface runoff is low. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/sec). Permeability is moderate (0.6 to 2.0 inches per hour).

USE AND VEGETATION: Soils are mostly cultivated. Common crops are corn, soybeans, wheat, and legume grass mixtures. Native vegetation is deciduous forest of oaks, beech and maple.

DISTRIBUTION AND EXTENT: Southwestern Indiana, southern Illinois, east-central Missouri, and southwestern Ohio. The series is of large extent in MLRAs 114A, 114B, 115A and 115B. The type location is in MLRA 115A.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana

SERIES ESTABLISHED: Pike County, Indiana

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of 38 cm (15 inches) (Ap, E and BE horizons); Argillic horizon - the zone from 38 to 137 cm (15 to 54 inches) (Bt1, Bt2, and BCt horizons); Redoximorphic features - the zone from 20 to 152 cm (8 to 60 inches).
Iva soils are in the mixed mineralogy class and are considered to contain more illitic clay minerals and less smectitic clay minerals.

National Cooperative Soil Survey
U.S.A.