LOCATION ORIO IL+IAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Mollic Endoaqualfs
TYPICAL PEDON: Orio loam - nearly level in a cultivated field. (Colors are for moist soil unless otherwise stated. When described, the soil was moist throughout.)
Ap--0 to 9 inches; very dark gray (10YR 3/1) loam, dark gray (10YR 4/1) dry; moderate medium granular structure; friable; many roots; moderately acid; abrupt smooth boundary. (6 to 10 inches thick)
E1--9 to 13 inches; grayish brown (10YR 5/2) fine sandy loam; light brownish gray (10YR 6/2) dry; common medium prominent strong brown (7.5YR 5/6) redox concentrations; weak medium platy structure; friable; common roots; moderately acid; clear smooth boundary.
E2--13 to 18 inches; grayish brown (10YR 5/2) fine sandy loam, light gray (10YR 7/2) dry; weak medium platy structure; friable; common roots; common medium prominent strong brown (7.5YR 5/6) redox concentrations; neutral; clear smooth boundary. (Combined thickness of the E horizon is 4 to 18 inches.)
Btg1--18 to 30 inches; dark grayish brown (10YR 4/2) clay loam; moderate medium subangular blocky structure; friable; common roots; few distinct dark grayish brown (2.5Y 4/2) clay films on faces of peds; common medium distinct yellowish brown (10YR 5/6) redox concentrations; neutral; clear wavy boundary.
Btg2--30 to 35 inches; olive gray (5Y 5/2) clay loam; moderate medium subangular blocky structure; friable; common roots; few faint olive gray (5Y 4/2) clay films on faces of peds; many medium prominent yellowish red (5YR 5/8) redox concentrations; neutral; clear wavy boundary. (Combined thickness of the Btg horizon is 10 to 25 inches.)
BCg--35 to 41 inches; grayish brown (2.5Y 5/2) sandy loam; weak medium subangular blocky structure; friable; few fine prominent yellowish red (5YR 5/8) redox concentrations; neutral; clear wavy boundary. (0 to 11 inches thick)
2Cg--41 to 60 inches; grayish brown (2.5Y 5/2) sand; single grain; loose; slightly alkaline.
TYPE LOCATION: Henry County, Illinois; about 7 miles north and 5 miles east of Geneseo; 1,190 feet west and 925 feet north of the southeast corner of sec. 8, T. 18 N., R. 4 E.
USGS Spring Hill quadrangle; elevation 610 feet; latitude 41 degrees, 33 minutes, 55 seconds N., longitude 90 degrees, 03 minutes, 23 seconds W.
RANGE IN CHARACTERISTICS: The solum commonly is between 35 and 55 inches in thickness, but ranges to 60 inches. It typically is moderately acid to neutral but some subhorizons range from very strongly acid to slightly alkaline. Free calcium carbonates are not within a depth of 60 inches. The average clay content of the particle size control section is 18 to 30 percent.
The upper 1/4 of the control section (Ap or A horizon) has value of 2 or 3 (3 through 5 dry), and chroma of 1 to 3. It is loam, sandy loam, fine sandy loam, or silt loam with a high percentage of sand. Sand content ranges from 35 to 70 percent.
The second 1/4 of the control section (E or Eg horizon) has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 1 or 2. It is loam, sandy loam, fine sandy loam, loamy sand, or loamy fine sand.
The third 1/4 of the control section (Btg and BC horizons) has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 or 2. Redox features have hue of 5YR, 7.5YR, 10YR or 2.5Y; value of 4 to 6; and chroma typically of 2 to 8. Exteriors of peds have hue of 10YR, 2.5Y, or 5Y; value of 4 or 5, and chroma of 1 or 2. The Btg horizon is sandy loam, fine sandy loam, loam, sandy clay loam, clay loam, or silty clay loam.
The lower 1/4 of the control section (2Cg horizon) has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 or 2. Many pedons have redox features with hue of 7.5YR, 10YR, or 2.5Y; value of 3 to 6; and chroma of 3 to 8. Some pedons have nearly even distribution of high and low chroma colors. The 2Cg horizon commonly is sand, fine sand, loamy fine sand, or loamy sand and many pedons are stratified. Thin strata with more clay or gravel or both are in some pedons. Average sand content ranges from 75 to 95 percent. The Cg horizon ranges from slightly alkaline to very strongly acid.
COMPETING SERIES: These are the Havana, Ilion, Mermill, Olmsted, and Varick series. Havana soils average less then 40 percent sand have in the upper 1/4 of the control section and do not have stratification in the lower part of the control section. Ilion, Mermill, and Varick soils average less than 75 percent sand in the lower part of the control section. Olmsted soils do not have an albic horizon and typically contain gravel in some part of the solum. Varick soils contain calcareous clayey shale soft fragments within a depth of 40 inches.
GEOGRAPHIC SETTING: Orio soils are on nearly level or depressional parts of stream terraces or outwash plains. Slopes typically are plane or concave with gradients of 0 to 2 percent. Orio soils formed in stratified loamy and sandy outwash or alluvium. Mean annual temperature ranges from 50 to 54 degrees F, and mean annual precipitation ranges from 35 to 42 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alvin, Bloomfield, Gilford, La Hogue, Onarga, Roby, and Selma soils. Alvin, Bloomfield, and Roby soils average less than 18 percent clay in the control section and do not have surface layers as much as 6 inches in thickness that have color value of 3 or less. Alvin and Bloomfield soils are on nearby ridges, slopes, and dunes. Roby soils are on slightly higher parts of outwash plains or stream terraces nearby. Gilford, La Hogue, Onarga, and Selma soils have mollic epipedons and do not have albic horizons. In addition, Gilford and Onarga soils average less than 18 percent clay in the control section; the somewhat poorly drained La Hogue soils have higher chroma in the matrix or on faces of peds in the upper part of the argillic horizon; and Selma soils do not have an argillic horizon. Gilford and Selma soils are on similar nearly level to depressional areas nearby. La Hogue and Onarga soils are on higher lying or more sloping parts of stream terraces or outwash plains.
DRAINAGE AND PERMEABILITY: Poorly drained or very poorly drained. Runoff is very slow or ponded. Permeability is moderately slow. A seasonal high water table is within a depth of 1 foot during spring in most years.
USE AND VEGETATION: Many areas are used for cultivated crops. Corn, soybeans, and meadow are the principal crops. Some undrained areas are too wet for cultivation and are used for pasture. Native vegetation is water tolerant grasses and sedges and scattered trees.
DISTRIBUTION AND EXTENT: Illinois and Iowa. Extent is moderate.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: St. Clair County, Illinois, 1931.
REMARKS: The Orio series was formerly classified as fine-loamy over sandy or sandy-skeletal Mollic Albaqualfs. We find that Orio soils lack both an abrupt textural change and a strongly contrasting particle size class. Diagnostic horizons and features recognized in this pedon are: mollic epipedon - 0 to 9 inches (Ap); argillic horizon - 18 to 35 inches (Btg1 and Btg2 horizons).
ADDITIONAL DATA: Data for some pedons of Orio are on file at the Illinois state office.