LOCATION PETROLIA IL+INEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Petrolia silty clay loam - nearly level in a cultivated field at an elevation of about 412 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; dark grayish brown (2.5Y 4/2) silty clay loam, light brownish gray (2.5Y 6/2) dry; moderate fine granular structure; friable; common very fine roots; few fine rounded black (N 2.5/0) and strong brown (7.5YR 4/6) masses of iron and manganese accumulation throughout; neutral; abrupt smooth boundary. (4 to 14 inches thick)
Bg--8 to 15 inches; dark gray (2.5Y 4/1) silty clay loam; weak medium subangular blocky structure; friable; few very fine roots; few faint dark gray (2.5Y 4/1) pressure faces on faces of peds; common fine prominent dark yellowish brown (10YR 4/4) and common fine faint dark grayish brown (2.5Y 4/2) masses of iron accumulation in the matrix; few fine rounded black (N 2.5/0) and strong brown (7.5YR 4/6) masses of iron and manganese accumulation throughout; slightly acid; clear smooth boundary.
Btg1--15 to 26 inches; gray (2.5Y 5/1) silty clay loam; weak fine prismatic structure parting to moderate medium subangular blocky; firm; few very fine roots; common distinct dark gray (2.5Y 4/1) clay films on faces of peds; common fine and medium prominent dark yellowish brown (10YR 4/4) masses of iron accumulation in the matrix; few fine and medium rounded black (N 2.5/0) nodules of iron and manganese oxides with sharp strong brown (7.5YR 4/6) boundaries and few fine irregular strong brown (7.5YR 5/6) masses of iron and manganese accumulation throughout; slightly acid; clear smooth boundary.
Btg2--26 to 42 inches; gray (2.5Y 5/1) silty clay loam; weak medium prismatic structure parting to weak medium and coarse subangular blocky; firm; few very fine roots; few distinct dark gray (2.5Y 4/1) clay films on faces of peds; common fine and medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few fine and medium rounded black (N 2.5/0) iron and manganese nodules with sharp strong brown (7.5YR 4/6) boundaries and common fine irregular strong brown (7.5YR 5/6) masses of iron and manganese accumulation throughout; slightly acid; gradual smooth boundary. (Combined thickness of the Bg and/or Btg horizons is 12 to 48 inches.)
BCg--42 to 55 inches; gray (2.5Y 5/1) silty clay loam; weak medium prismatic structure; firm; few very fine roots; few distinct dark gray (2.5Y 4/1) clay films lining root channels and pores; common medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few medium rounded black (7.5YR 2.5/1) iron and manganese nodules with clear strong brown (7.5YR 5/6) boundaries and common fine and medium irregular strong brown (7.5YR 4/6) masses of iron and manganese accumulation throughout; slightly acid; gradual smooth boundary. (0 to 18 inches thick)
Cg1--55 to 73 inches; gray (2.5Y 6/1) silty clay loam; massive; firm; few very fine roots in old root channels; few distinct dark gray (2.5Y 4/1) clay films lining root channels and pores; many fine and medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few medium rounded black (7.5YR 2.5/1) iron and manganese nodules with clear strong brown (7.5YR 5/6) boundaries and common fine and medium irregular strong brown (7.5YR 4/6) masses of iron and manganese accumulation throughout; neutral; diffuse smooth boundary.
Cg2--73 to 90 inches; gray (2.5Y 6/1) silty clay loam; massive; firm; common medium and coarse prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few fine irregular black (7.5YR 2.5/1) iron and manganese nodules with clear strong brown (7.5YR 5/6) boundaries and few fine and medium irregular strong brown (7.5YR 4/6) masses of iron and manganese oxides throughout; dark gray (2.5Y 4/1) krotovina; neutral.
TYPE LOCATION: Clinton County, Illinois; about 3 miles south of Bartelso; 400 feet south and 800 feet west of the center of sec. 29, T. 1 N., R. 3 W.; USGS Addieville topographic quadrangle; lat. 38 degrees 29 minutes 56 seconds N. and long. 89 degrees 27 minutes 28 seconds W.; NAD 1927; MLRA 114.
RANGE IN CHARACTERISTICS: The particle-size control section averages between 27 and 35 percent clay and less than 15 percent fine sand or coarser. Content of rock fragments is less than 2 percent throughout the series control section. Carbonates are not present within a depth of 60 inches. It has an irregular decrease in organic carbon content with increasing depth. Mean annual soil temperature at 20 inches is 54 to 59 degrees F.
The Ap or A horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 1 or 2. Some pedons have a thin surface layer with color value of 3. Redoximorphic features have hue of 5YR, 7.5YR, 10YR, or 2.5Y, value of 2 to 5, and chroma of 2 to 8. Texture is silty clay loam or, less commonly, silt loam. Clay content ranges from 20 to 35 percent and sand content is less than 20 percent. Reaction ranges from moderately acid to moderately alkaline.
The Bg, Btg and/or BCg horizons have hue of 10YR, 2.5Y, 5Y, or is neutral, value of 4 to 6, and chroma of 0 to 2. Redoximorphic features have hue of 5YR, 7.5YR, 10YR, or 2.5Y, value of 2 to 6, and chroma of 1 to 8. Texture is silty clay loam. Clay content ranges from 27 and 35 percent clay and sand content is less than 15 percent. Reaction ranges from moderately acid to neutral.
The Cg horizon has hue of 10YR, 2.5Y, 5Y, or is neutral, value of 4 to 6, and chroma of 0 to 2. Redoximorphic features have hue of 5YR, 7.5YR, 10YR, or 2.5Y, value of 2 to 6, and chroma of 1 to 8. Texture is commonly silty clay loam, but below a depth of 40 inches, some pedons are silt loam and some contain thin strata of silty clay, silt loam, loam, or fine sandy loam. Clay content ranges from 20 to 35 percent clay and averages less than 40 percent sand. Reaction ranges from strongly acid to slightly alkaline.
COMPETING SERIES: These are the Aetna, Puget, and Wick (T) series. Aetna soils have a buried, dark soil at depths of less than 36 inches. Puget soils formed in a mild marine climate and typically have strata of sand or loamy sand in the lower part of the soil profile. Puget and Wick (T) soils have a mean annual soil temperature of less than 54 degrees F.
GEOGRAPHIC SETTING: Petrolia soils are on nearly level or slightly depressional parts of flood plains or on flooded parts of glacial lake plains. Slopes range from 0 to 2 percent. Petrolia soils formed in light colored, moderately fine textured or medium textured alluvium. Mean annual air temperature ranges from 52 to 57 degrees F., mean annual precipitation ranges from 38 to 48 inches, frost free days range from 180 to 200, and elevation ranges from 340 to 500 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Birds, Bonnie, Karnak, Piopolis, and Zipp soils. Birds and Bonnie soils commonly are on flood plains of smaller streams or are closer to the upland source of sediments on larger flood plains and glacial lake plains. Karnak soils are farther from the stream channel or on lower-lying parts of flood plains; they contain more clay in the control section. Piopolis soils are on similar parts of flood plains nearby; they are more acidic in the control section. Zipp soils are nearby on the main body of glacial lake plains and contain more clay in the control section.
DRAINAGE AND PERMEABILITY: Poorly drained and very poorly drained. The potential for surface water runoff is low or negligible. Permeability is moderately slow. Flooding from stream overflow is rare to frequent during late winter and early spring. In the undrained condition, these soils have an apparent seasonal high water table as much as 2 feet above the surface at some time during the year in most years. Where drained, the water table is 0.5 foot above the surface to 1 foot below at some time between November and May in normal years.
USE AND VEGETATION: Most areas are used to grow corn and soybeans. Some areas are in forestland or pastureland. Native vegetation is hardwood trees.
DISTRIBUTION AND EXTENT: Southern and south-central Illinois, and southwestern Indiana in MLRAs 111, 113, 114, and 115. Extent is large (slightly more than 100,000 acres correlated).
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Lawrence County, Illinois, 1952.
REMARKS: With this update, the type location is moved to a more representative site in Clinton County, Illinois and is reclassified as an Inceptisol.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 8 inches (Ap horizon); cambic horizon - the zone from 8 to 55 inches; aquic conditions - chroma of 1 and redox concentrations below the Ap horizon.
ADDITIONAL DATA: Lab data is on file for several pedons including the typical pedon at the Illinois state office and at the NSSL.