LOCATION SELMA IL+INEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Endoaquolls
TYPICAL PEDON: Selma loam - on a nearly level lake plain in a cultivated field at an elevation of 200 meters (656 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 15 centimeters (0 to 6 inches); black (10YR 2/1) loam, dark gray (10YR 4/1) dry; weak fine and medium granular structure; friable; common very fine and fine roots; neutral; gradual smooth boundary.
A--15 to 33 centimeters (6 to 13 inches); black (10YR 2/1) clay loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure; friable; common fine roots; neutral; gradual wavy boundary. (Combined thickness of the A horizon is 25 to 58 centimeters or 10 to 23 inches.)
Btg1--33 to 48 centimeter (13 to 19 inches); dark grayish brown (2.5Y 4/2) clay loam; moderate fine and medium subangular blocky structure; friable; common fine roots; many prominent very dark gray (2.5Y 3/1) organo-clay films on faces of peds and on surfaces along pores; few fine distinct yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; neutral; gradual wavy boundary.
Btg2--48 to 71 centimeters (19 to 28 inches); grayish brown (2.5Y 5/2) loam; moderate medium prismatic structure parting to moderate medium subangular blocky; friable; common fine roots; many prominent dark gray (2.5Y 4/1) clay films on faces of peds; few fine distinct light olive brown (2.5Y 5/4) iron-manganese nodules throughout; common medium distinct olive brown (2.5Y 4/4) iron-manganese accumulations in the matrix; slightly alkaline; gradual wavy boundary.
Btg3--71 to 99 centimeters (28 to 39 inches); grayish brown (2.5Y 5/2) loam; weak fine and medium subangular blocky structure; friable; common fine roots; few distinct dark gray (2.5Y 4/1) clay films on faces of peds; black (N 2.5/) krotovina at a depth of 76 to 99 centimeters (30 to 39 inches); few fine prominent dark yellowish brown (10YR 4/6) iron-manganese nodules throughout; few fine prominent light olive brown (2.5Y 5/6) masses of oxidized iron in the matrix; slightly alkaline; gradual wavy boundary. (Combined thickness of the Btg horizon is 33 to 84 centimeters or 13 to 33 inches.)
BCtg--99 to 112 centimeters (39 to 44 inches); grayish brown (2.5Y 5/2) loam; weak medium subangular blocky structure; friable; few very fine roots; few faint dark gray (2.5Y 4/1) clay films on faces of peds; few fine prominent dark yellowish brown (10YR 4/6) iron-manganese nodules throughout; few fine prominent light olive brown (2.5Y 5/6) masses of oxidized iron in the matrix; strongly effervescent; slightly alkaline; gradual wavy boundary. (0 to 30 centimeters thick or 0 to 12 inches thick)
Cg1--112 to 137 centimeters (44 to 54 inches); 55 percent dark gray (2.5Y 4/1), 35 percent gray (2.5Y 5/1), and 10 percent light yellowish brown (2.5Y 6/4) stratified sandy loam and loamy sand; massive in the sandy loam and single grain in the loamy sand; friable in the sandy loam and loose in the loamy sand; few very fine roots; violently effervescent; moderately alkaline; gradual wavy boundary.
Cg2--137 to 203 centimeters (54 to 80 inches); 45 percent dark gray (2.5Y 4/1), 45 percent gray (2.5Y 5/1), and 10 percent light olive brown (2.5Y 5/6) stratified silt loam, sandy loam, and loamy sand; massive in the silt loam and sandy loam and single grain in the loamy sand; friable in the silt loam and sandy loam and loose in the loamy sand; few very fine roots; strongly effervescent; moderately alkaline.
TYPE LOCATION: Iroquois County, Illinois; about 13 kilometers (8 miles) northwest of Ashkum; 16 meters (52 feet) south and 49 meters (160 feet) west of the northeast corner of sec. 18, T. 28 N., R. 10 E.; USGS Piper City NE topographic quadrangle; lat. 40 degrees 54 minutes 36 seconds N. and long. 88 degrees 06 minutes 44 seconds W., NAD 27; UTM Zone 16, 0406337 easting and 4529366 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of the cambic horizon ranges from 89 to 140 centimeters (35 to 55 inches). The mollic epipedon ranges from 25 to 61 centimeters (10 to 24 inches) in thickness and extends into the upper part of the B horizon in some pedons. The particle-size control section averages between 20 and 30 percent clay.
The Ap or A horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is loam or clay loam, and less commonly is fine sandy loam, silt loam, or silty clay loam. Reaction ranges from slightly acid to slightly alkaline.
The Bg, Btg, BCg, or BCtg 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 chroma ranging from 1 to 8. Texture is loam or clay loam, but subhorizons may be silty clay loam, silt loam, sandy clay loam, fine sandy loam, or sandy loam. The average clay content ranges from 20 to 30 percent and average sand content ranges from 25 to 45 percent. The content of rock fragments averages less than 10 percent. Reaction ranges from slightly acid to moderately alkaline.
The Cg or C horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 to 6. It is stratified sandy loam, loam, silt loam, loamy sand, or sand. Clay content ranges from 3 to 15 percent. Sand content averages between 50 and 90 percent of which less than 50 percent is very fine and fine. Individual subhorizons have as much as 95 percent sand. It contains from 0 to 15 percent rock fragments. Reaction ranges from neutral to moderately alkaline.
COMPETING SERIES: These are the Clyde, Faxon, Kossuth, Letri, Marengo, Mound Creek, Reddick, Selmass, Tripoli, Webster, and Wolcott series. Clyde soils have greater than 15 percent clay in the lower part of the series control section and less than 50 percent sand in the lower third of the series control section. Faxon and Mound Creek soils have a lithic contact within a depth of 152 centimeters (60 inches). Kossuth soils average more than 30 percent clay in the upper part of the particle-size control section. Letri soils have firm glacial till in the lower half of the series control section. Marengo, Reddick, and Wolcott soils average more than 15 percent clay and less than 50 percent total sand in the lower part of the series control section. Selmass soils average more than 80 percent sand and less than 10 percent clay in the lower part of the series control section. Tripoli soils have greater than 15 percent clay in the lower part of the series control section. Webster soils have a sand fraction in the lower part of the series control section which averages less than 50 percent medium or coarser sand.
GEOGRAPHIC SETTING: The Selma soils are in depressions or on broad low summits on outwash plains, stream terraces, high flood plains, or glacial lake plains. Slopes range from 0 to 2 percent. Selma soils formed in loamy material 102 to 152 centimeters (40 to 60 inches) thick and typically are underlain by stratified coarse-textured materials. Mean annual air temperature ranges from 7 to 12 degrees C (45 to 54 degrees F), mean annual precipitation ranges from 760 to 1,020 millimeters (30 to 40 inches), frost-free period ranges from 160 to 180 days, and elevation ranges from 207 to 311 meters (680 to 1,020 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Darroch, Gilford, Jasper, La Hogue, and Ridgeville soils. The somewhat poorly drained Darroch soils and the well drained Jasper soils are in a drainage sequence with the Selma soils and are on higher landform positions. Gilford soils are coarse-loamy and on similar landform positions nearby. La Hogue and Ridgeville soils are somewhat poorly drained and are on slightly higher landform positions.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. Where drained, the apparent seasonal high water table is 15 centimeters (0.5 foot) above the surface to 30 centimeters (1.0 foot) below the surface at some time between January and May in most years. In the undrained condition, the apparent seasonal high water table is 15 centimeters (0.5 foot) above the surface to 15 centimeters (0.5 foot) below the surface at some time between November and June in most years. The potential for surface runoff is negligible. Saturated hydraulic conductivity is moderately high to high (4.23 to 14.11 micrometers per second). Permeability is moderate.
USE AND VEGETATION: Most areas are cultivated. Principal crops are corn and soybeans. Native vegetation is hydrophytic grasses, reeds, and sedges.
DISTRIBUTION AND EXTENT: North-central and northern Illinois, and northern Indiana. The extent is large; more than 118,000 hectares (294,000 acres) are correlated in MLRAs 95B, 108A, 108B, 110, 111C, 111D, 115A, and 115C,
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Wabash County, Illinois, 1931.
REMARKS: A sandy loam surface, sandy substratum, and till substratum phase is recognized. The phases will be examined during MLRA update activities. Possibly new soil series will be established for these soils and minimally new data mapunits will be developed.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface to a depth of 33 centimeters (13 inches) (Ap and A horizons); cambic horizon - the zone from 33 to 112 centimeters (13 to 44 inches) (Btg1, Btg2, Btg3, and BCtg horizons); aquic moisture regime - redoximorphic features present in the zone from 33 to 203 centimeters (13 to 80 inches) (Btg1, Btg2, Btg3, BCtg, Cg1, and Cg2 horizons).