LOCATION IPAVA IL+INEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aquic Argiudolls
TYPICAL PEDON: Ipava silt loam- nearly level in a cultivated field at an elevation of about 804 feet (245 meters) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 25 cm (0 to 10 inches); black (10YR 2/1) silt loam, dark gray (10YR 4/1) dry; moderate fine and medium subangular blocky structure; friable; moderately acid; abrupt smooth boundary.
A--25 to 46 cm (10 to 18 inches); very dark grayish brown (10YR 3/2) silty clay loam, grayish brown (10YR 5/2) dry; weak fine and medium subangular blocky structure; friable; common distinct black (10YR 2/1) organic coatings on faces of peds; moderately acid; clear smooth boundary. [Combined thickness of the A horizon is 25 to 61 cm (10 to 24 inches).]
BA--46 to 61 cm (18 to 24 inches); brown (10YR 4/3) silty clay loam; moderate fine and medium subangular blocky structure; friable; common distinct very dark gray (10YR 3/1) organic coatings on faces of peds; few fine distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; few fine distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; moderately acid; clear smooth boundary. [0 to 7 inches (0 to 18 cm) thick]
Btg1--61 to 79 cm (24 to 31 inches); dark grayish brown (10YR 4/2) silty clay; moderate fine prismatic structure parting to moderate fine subangular blocky; friable; common distinct dark gray (10YR 4/1) clay films on faces of peds; few fine distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; common fine prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; slightly acid; clear smooth boundary.
Btg2--79 to 94 cm (31 to 37 inches); grayish brown (2.5Y 5/2) silty clay loam; moderate medium prismatic structure parting to moderate medium angular blocky; friable; common distinct dark gray (10YR 4/1) clay films on faces of peds; common fine faint light brownish gray (2.5Y 6/2) iron depletions in the matrix; common medium prominent strong brown (7.5YR 5/8) masses of iron accumulation in the matrix; few fine prominent black (7.5YR 2.5/1) very weakly cemented iron-manganese concretions throughout; few fine black (7.5YR 2.5/1) iron-manganese stains on faces of peds; slightly alkaline; gradual smooth boundary. [Combined thickness of the Bt horizon is 30 to 91 cm (12 to 36 inches).]
BCg--94 to 127 cm (37 to 50 inches); grayish brown (2.5Y 5/2) silty clay loam; moderate medium prismatic structure parting to moderate medium angular blocky; friable; few distinct very dark grayish brown (10YR 3/2) organo-clay films as linings in pores and on a few vertical faces of peds; common fine faint light brownish gray (2.5Y 6/2) iron depletions in the matrix; common fine prominent strong brown (7.5YR 5/8) masses of oxidized iron in the matrix; few fine prominent black (7.5YR 2.5/1) very weakly cemented iron-manganese concretions throughout; common fine prominent black (7.5YR 2.5/1) iron-manganese stains on faces of peds; slightly alkaline; clear smooth boundary. [0 to 38 cm (0 to l5 inches) thick]
Cg--127 to 152 cm (50 to 60 inches); light brownish gray (2.5Y 6/2) silt loam; massive; friable; few faint very dark grayish brown (10YR 3/2) organo-clay films as linings in pores; common fine prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; few fine prominent black (7.5YR 2.5/1) very weakly cemented iron-manganese concretions throughout; few fine prominent black (7.5YR 2.5/1) iron and manganese oxide stains on faces of vertical cracks; moderately alkaline.
TYPE LOCATION: Knox County, Illinois; about 0.25 mile northeast of Oneida; 2,046 feet west and 594 feet north of the southeast corner of sec. 25, T. 13 N., R. 2 E.; USGS Oneida topographic quadrangle; lat. 41 degrees 4 minutes 40 seconds N. and long. 90 degrees 13 minutes 3 seconds W; NAD 27; UTM zone 15 0733740 easting and 4551126 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 89 to 140 cm (35 to 55 inches). The thickness of the mollic epipedon ranges from 25 to 61 cm (10 to 24 inches). The depth to carbonates is greater than 102 cm (40 inches). The particle-size control section averages between 35 and 42 percent clay. The series control section averages less than 10 percent sand in all parts.
The Ap, A, or AB horizon has hue of 10YR, value of 2 or 3 (4 or 5 dry), and chroma of 1 or 2. It is silt loam or silty clay loam. Reaction ranges from moderately acid to neutral depending upon liming practices.
The BA, Bt, Btg, BC, or BCg horizon has hue of 10YR or 2.5Y, value of 3 to 6, and chroma of 2 to 4. Texture is silty clay loam or silty clay, with lower subhorizons of silt loam in some pedons. The depth to maximum clay content ranges from 20 and 30 inches (51 to 76 cm). Reaction ranges from moderately acid in the upper horizons to slightly alkaline in the lower horizons.
The Cg or C horizon has hue of 10YR or 2.5Y, value of 5 or 6, and chroma 1 to 4. Some pedons have redoximorphic colors with nearly equal proportions of high and low chroma. Average clay content ranges 18 to 25 percent. Reaction ranges from slightly acid to moderately alkaline.
COMPETING SERIES: These are the Biddle, Flanagan, Herrick, Macksburg, Malvern, Rutland and Timewell soils in the same family. Soils in closely related families are the Adair, Arisburg, Arispe, Chase, Greenton, Grundy, Lagonda, Lamoni, Mahaska, Martin, Mayberry, Pawnee, Seymour, Shorewood, Tina, and Wymore soils. Biddle soils have 5 to 15 percent exchangeable sodium in the subsoil. Flanagan and the related Adair, Lagonda, Lamoni, Pawnee, Shorewood, and Tina soils average more than 10 percent sand in the lower part of the series control section. Herrick and Timewell soils have an AE or E horizon or a moist color value more than 3 in the upper part of the control section. Macksburg, Malvern, Greenton, and Rutland soils average more than 25 percent clay in the lower part of the series control section. In addition, Macksburg soils do not have carbonates within a depth of 72 inches. Arisburg soils do not have reaction of more than neutral in any horizon in the middle or lower parts of the series control section. Arispe soils have the maximum content of clay at depths less than 20 inches. Chase and Martin soils have mollic epipedons more than 24 inches thick. Grundy, Seymour, and Wymore soils average more than 42 percent clay in the particle-size control section. Mahaska soils have less contrast in clay content between the A and B horizons and are dominantly deeper than 6 feet to silt loam textures. Mayberry soils have hue redder than 10YR in the middle part of the series control section.
GEOGRAPHIC SETTING: Ipava soils are on nearly level to gently sloping broad summits on uplands. Slope gradients typically are between 1 and 3 percent and range from 0 to 5 percent. Ipava soils formed in loess. Mean annual temperature ranges from 8 to 13 degrees C (46 to 56 degrees F), mean annual precipitation ranges from 737 to 1016 mm (29 to 40 inches), frost free days range from 160 to 180 days, and elevation ranges from 107 to 396 meters (350 to 1300 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Clarksdale, Denny, Osco, Sable, Tama, and Virden soils. Clarksdale soils are on similar landscapes nearby, but are typically nearer the drainageways. The poorly drained Denny soils have albic horizons and are in depressional areas. The well drained Osco and Tama soils contain less clay in the subsoil and are more sloping or are on narrower ridges in areas with greater relief. The poorly drained Sable soils contain less clay in the subsoil and are nearby on the parts of the inter-stream divides with lowest relief. The poorly drained Virden soils typically are nearby on the parts of the inter-stream divides with lowest relief.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. An apparent seasonal high water table is at a depth of 30 to 61 cm (1 to 2 feet) below the surface at some time between January and May in normal years. The potential for surface runoff is low or medium. Saturated hydraulic conductivity is moderately low or moderately high (0.42 to 1.41 micrometers per second). Permeability is moderately slow (0.2 to 0.6 inches per hour).
USE AND VEGETATION: Most areas of this soil are cultivated. Corn, soybeans, and small grain are the principal crops. Native vegetation is prairie grass.
DISTRIBUTION AND EXTENT: Illinois and Indiana. Ipava soils are extensive. More than 785,000 acres have been correlated in MLRAs 108A, 108B, 114B, 115B and 115C.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Christian County, Illinois, 1946.
REMARKS: Diagnostic horizons recognized in this pedon are:
mollic epipedon - the zone from the surface to a depth of 18 inches (46 cm), (Ap and A horizons); argillic horizon - the zone from approximately 24 to 37 inches (61 to 94 cm), (Btg1 and Btg2 horizons).
ADDITIONAL DATA: Data on numerous pedons are on file at the Illinois State office.