LOCATION ONARGA IL+IN
Established Series
Rev. HRM-JWS-JKH
02/2011
ONARGA SERIES
The Onarga series consists of very deep, well drained soils formed in glacial outwash or eolian deposits on stream terraces and outwash plains. Slope ranges from 0 to 10 percent. Mean annual precipitation is about 914 mm (36 inches), and mean annual air temperature is about 11.1 degrees C (52 degrees F).
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Typic Argiudolls
TYPICAL PEDON: Onarga sandy loam on a 1 percent north-facing convex slope in a cultivated field at an elevation of about 151 meters (495 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 25 cm (0 to 10 inches); very dark grayish brown (10YR 3/2) sandy loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure parting to weak fine granular; friable; common very fine roots throughout; many faint very dark gray (10YR 3/1) organic coatings on faces of peds; slightly acid; abrupt smooth boundary.
A--25 to 46 cm (10 to 18 inches); very dark grayish brown (10YR 3/2) sandy loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure parting to weak fine granular; friable; common very fine roots throughout; many faint very dark gray (10YR 3/1) organic coatings on faces of peds; slightly acid; abrupt smooth boundary. [Combined thickness of the A horizons is 25 to 51 cm (10 to 20 inches).]
Bt1--46 to 64 cm (18 to 25 inches); brown (10YR 4/3) sandy loam; moderate medium subangular blocky structure; friable; common very fine roots throughout; many distinct very dark grayish brown (10YR 3/2) and common distinct dark brown (10YR 3/3) organo-clay films on faces of peds; moderately acid; clear smooth boundary.
Bt2--64 to 84 cm (25 to 33 inches); dark yellowish brown (10YR 4/4) sandy loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; few very fine roots throughout; common distinct dark brown (10YR 3/3) organo-clay films on faces of peds; moderately acid; clear smooth boundary. [Combined thickness of the Bt horizons is 25 to 64 cm (10 to 25 inches).]
BC--84 to 91 cm (33 to 36 inches); dark yellowish brown (10YR 4/6) loamy sand; weak medium prismatic structure parting to weak medium subangular blocky; very friable; few very fine roots throughout; moderately acid; gradual smooth boundary. [0 to 38 cm (0 to 15 inches) thick]
C1--91 to 160 cm (36 to 63 inches); dark yellowish brown (10YR 4/6) sand; single grain; loose; moderately acid; gradual smooth boundary.
C2--160 to 203 cm (63 to 80 inches); 50 percent dark yellowish brown (10YR 4/4) and 50 percent brown (7.5YR 4/4) stratified loamy sand and sand; single grain; loose; 2 percent fine gravel; slightly acid.
TYPE LOCATION: Mason County, Illinois; about 1 mile south of Forest City; 2,530 feet south and 2,350 feet east of the northwest corner of section 18, T. 22 N., R. 6 W.; USGS Forrest City, Illinois topographic quadrangle; lat. 40 degrees 21 minutes 17 seconds N. and long. 89 degrees 49 minutes 11 seconds W.; NAD 27.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon: 25 to 51 cm (10 to 20 inches)
Depth to the base of the argillic horizon: 64 to 102 cm (25 to 40 inches)
Average content of clay in the particle-size control section: between 12 and 18 percent
Average content of total sand in the series control section: between 45 and 75 percent, sand size is dominantly medium sand and finer in all layers of the series control section.
Ap or A horizon:
Hue: 10YR or 7.5YR
Value: 2 or 3, value of 3 to 5 dry
Chroma: 1 to 3
Texture: sandy loam or fine sandy loam
Reaction: strongly acid to slightly alkaline depending upon liming practices
Some pedons have an AB or BA horizon.
Bt horizon:
Hue: 10YR or 7.5YR
Value: 4 or 5
Chroma: 3 to 6
Texture: typically loam or sandy loam. Individual subhorizons are fine sandy loam, sandy clay loam or clay loam.
Redoximorphic features: some pedons have redoximorphic features with chroma that range to 8.
Reaction: commonly slightly acid or moderately acid, but ranges from very strongly acid to neutral.
BC horizon:
Hue: 10YR or 7.5YR
Value: 4 to 6
Chroma: 3 to 6
Texture: typically sandy loam or loamy sand and includes textures of fine sandy loam and loamy fine sand.
Redoximorphic features: some pedons have redoximorphic features with chroma that range to 8.
Reaction: strongly acid to neutral
C or 2C horizon:
Hue: 10YR or 7.5YR
Value: 4 to 6
Chroma: 4 to 6
Texture: typically stratified strata include loamy fine sand, fine sand, fine sandy loam, loamy sand, sand, sandy loam, loam, and silt loam. The content of very fine sand plus fine sand is greater than the content of coarse sand plus very coarse sand. Reaction: moderately acid to neutral
Rock fragment content: less than 2 percent
COMPETING SERIES: These are the
Eden Prairie,
Malardi,
Norborne, and
Rasset series. Eden Prairie soils do not have stratified textures in the C horizon. Malardi soils have free carbonates within 46 cm (18 inches) of the surface and contain more than 2 percent coarse fragments in the lower part of the series control section. Norborne soils have mollic epipedons greater than 61 cm (24 inches) thick. Rasset soils have, in the lower part of the series control section, more coarser sand and very coarse sand than fine sand and very fine sand.
GEOGRAPHIC SETTING: Onarga soils formed in 76 to 127 cm (30 to 50 inches) of eolian or water sorted loamy material and the underlying stratified outwash. They are on summits, shoulders and backslopes on stream terraces, outwash plains, beach ridges and lake plains. Slope gradients range from 0 to 10 percent. Mean annual air temperature ranges from 8.9 to 12.8 degrees C (48 to 55 degrees F), mean annual precipitation ranges from 813 to 1016 mm (32 to 40 inches), frost free days ranges from 160 to 190 days, and elevation ranges from 107 to 213 meters (350 to 700 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Ade,
Jasper,
La Hogue,
Ridgeville, and
Selma soils. The Ade and Jasper soils are on similar landforms as Onarga soils. Ade soils have argillic horizons that consist of lamellae or bands. Jasper soils average more than 18 percent clay in the particle-size control section. The somewhat poorly drained La Hogue soils and the poorly drained Selma soils have more clay in the particle-size control section and are on slightly lower positions in the landscape. The somewhat poorly drained Ridgeville soils form a drainage sequence with the Onarga soils and are on adjoining lower elevations.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. The potential for surface runoff ranges from negligible to medium. Saturated hydraulic conductivity is moderately high to high (4.23 to 42.34 micrometers per second) in the upper part of the series control section and high to very high (42.34 to 141.14 micrometers per second) in the lower part. Permeability is moderate or moderately rapid in the upper part of the series control section and rapid in the lower part. A rarely flooded phase is recognized.
USE AND VEGETATION: Most areas are cultivated. Corn and soybeans are the principal crops. Native vegetation is prairie grasses.
DISTRIBUTION AND EXTENT: Illinois and southern Indiana in MLRAs 108A, 108B, 110, 115A, 115B, and 115C. The soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Vermilion County, Illinois, 1931.
REMARKS: The type location was moved in May, 2000. Lab data for the previous typical pedon did not support placement in the coarse-loamy textural family. The percent clay in the particle-size control section has been expanded from 12 to 18 percent.
Diagnostic horizons and features recognized in this pedon are:
mollic epipedon -zone from the surface to a depth of 46 cm (18 inches) (Ap and A horizons);
argillic horizon -zone from approximately 46 to 84 cm (18 to 33 inches) (Bt1 and Bt2 horizons).
Additional Data: Site of typical pedon 85IL-125-046 from Mason County Illinois, University of Illinois Soil Characterization Lab.
National Cooperative Soil Survey
U.S.A.