LOCATION ELPASO ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Endoaquolls
TYPICAL PEDON: Elpaso silty clay loam - on a nearly level slope in a cultivated field at an elevation of 218 meters (715 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 cm (0 to 7 inches); very dark gray (10YR 3/1) silty clay loam, gray (10YR 5/1) dry; weak very fine granular structure; firm; many very fine and fine roots; moderately acid; abrupt smooth boundary.
A--18 to 53 cm (7 to 21 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine and medium subangular blocky structure; firm; many very fine andfine roots; moderately acid; gradual wavy boundary. (Combined thickness of the A horizon is 25 to 61 cm or 10 to 24 inches.)
Bg--53 to 89 cm (21 to 35 inches); dark grayish brown (2.5Y 4/2) silty clay loam; moderate fine prismatic structure parting to moderate medium subangular blocky; friable; many fine roots; many distinct very dark grayish brown (10YR 3/2) organic coatings onfaces of peds; few fine distinct light olive brown (2.5Y 5/4) masses of oxidized iron in the matrix; few fine extremely weakly cemented iron-manganese accumulations throughout; neutral; gradual wavy boundary.
Btg1--89 to 112 cm (35 to 44 inches); dark grayish brown (2.5Y 4/2) silty clay loam; moderate fine prismatic structure parting to moderate medium subangular blocky; friable; common fine roots; common distinct dark gray (10YR 4/1) clay films on faces of peds; common fine prominent yellowish brown (10YR 5/6) and few fine distinct light olive brown (2.5Y 5/4) masses of oxidized iron in the matrix; common fine extremely weakly cemented iron-manganese accumulations throughout; neutral; gradual wavy boundary. (Combined thickness of the Bg and Btg horizons is 46 to 122 cm or 18 to 48 inches.)
2Btg2--112 to 135 cm (44 to 53 inches); dark grayish brown (2.5Y 4/2) silt loam; weak medium and coarse subangular blocky structure; friable; few fine roots; common distinct dark gray (10YR 4/1) clay films on faces of peds; common medium prominent yellowish brown (10YR 5/6) and common fine distinct light olive brown (2.5Y 5/4) masses of oxidized iron in the matrix; common fine extremely weakly cemented iron-manganese accumulations throughout; 5 percent pebbles; slightly alkaline; clear wavy boundary.
2Btg3--135 to 175 cm (53 to 69 inches); dark grayish brown (2.5Y 4/2) and olive brown (2.5Y 4/4) silty clay loam; weak medium and coarse prismatic structure; firm; few distinct dark gray (10YR 4/1) clay films on faces of peds; many medium prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common fine faint olive gray (5Y 5/2) iron depletions throughout; few fine extremely weakly cemented iron-manganese accumulations throughout; 4 percent pebbles; slightly effervescent starting at 63 inches; slightly alkaline; diffuse wavy boundary. (Combined thickness of the Bg, Btg, and 2Btg horizons is 38 to 89 cm or 15 to 35 inches.)
2C--175 to 203 cm (69 to 80 inches); olive brown (2.5Y 4/4) silty clay loam; massive; firm; many medium distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common fine distinct olive gray (5Y 5/2) iron depletions throughout; few fine extremely weakly cemented iron-manganese accumulations throughout; 4 percent pebbles; strongly effervescent; moderately alkaline.
TYPE LOCATION: Woodford County, Illinois; about 2 miles (3.2 kilometers) north of El Paso: 210 feet (64 meters) north and 320 feet (97 meters) west of the southeast corner of sec. 30, T. 27 N., R. 2 E.; USGS Benson topographic quadrangle; lat. 40 degrees 45 minutes 59.7 seconds N. and long. 89 degrees 1 minute 34 seconds W., NAD 27; UTM Zone 16, 328989 easting and 4514825 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base soil development ranges from 114 to 191 cm (45 to 75 inches). The mollic epipedon is commonly 36 to 46 cm (14 to 18 inches) thick but ranges from 25 to 61 cm (10 to 24 inches). The depth to carbonates ranges from 89 to 165 cm (35 to 65 inches). The depth to glacial till ranges from 102 to 152 cm (40 to 60 inches). The particle-size control section 25 to 102 cm (10 to 40 inches) averages from 27 to 35 percent clay. The solum ranges from moderately acid to moderately alkaline.
The Ap or A horizon has hue of 10YR or is neutral; value of 2 or 3, and chroma of 0 to 2. It is commonly silty clay loam, but a few pedons are silt loam. Some pedons have an AB or BA horizon.
The Bg and/or Btg horizon has hue of 10YR, 2.5Y, 5Y or is neutral; value of 4 to 6, and chroma of 0 to 2. Most pedons have redoximorphic features. Texture is commonly silty clay loam, but includes silt loam and silty clay. Sand content ranges from 1 to 10 percent, and clay content ranges 24 to 42 percent.
The 2Btg and/or 2BCg horizon has hue of 10YR, 2.5Y, 5Y or is neutral; value of 4 to 6, and chroma of 0 to 4 . Most pedons have redoximorphic features. Texture is commonly silty clay loam, but includes silt loam, loam, and clay loam. Sand content ranges from 2 to 30 percent, and clay content ranges 15 to 40 percent. It contains 1 to 10 percent pebbles.
The 2C horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 1 to 8. It is commonly silty clay loam, but includes silt loam, loam, and clay loam. Sand content ranges from 2 to 30 percent, and clay content ranges 15 to 30 percent. It contains 1 to 10 percent pebbles.
COMPETING SERIES: These are the
Chalmers,
Chetomba,
Dolbee,
Drummer,
Dunham,
Elvira,
Garwin,
Gillett Grove,
Hartsburg,
Madelia,
Marcus,
Mascoutah,
Maxcreek,
Maxfield,
Maxmore,
Ossian,
Patton,
Pella,
Rushmore,
Sable,
Wacousta series. Chetomba soils have carbonates within a depth of 102 cm (40 inches). Dolbee,
Elvira, and Ossian soils formed in silty alluvial sediments on flood plains and river terraces and are subject to flooding. In addition Elvira soils also have high concentrations of iron and manganese oxides in the solum. Chalmers and Maxcreek soils have a loess mantle less than 102 cm (40 inches) thick. Dunham soils contain more than 15 percent rock fragments in the lower part of the series control section. Garwin and Sable soils contain less sand in the lower part of the B horizon and in the C horizon. Gillett Grove soils contain 25 to 45 percent fine sand and coarser in the lower part of the series control section.
Hartsburg, Madelia, Pella, Rushmore, and Wacousta soils typically have thinner sola and carbonates at depths between 30 and 102 cm (12 to 40 inches). Marcus soils have a depth to glacial till of greater than 152 cm (60 inches). Mascoutah soils contain less than 7 percent sand in the lower part of the series control section. Maxfield soils formed in loess less than 102 cm (40 inches) thick and in loam till. Maxmore soils contain 30 to 70 percent sand in the lower part of the series control section. Patton soils have sola between 61 to 107 cm (24 to 42 inches) thick and C horizons of stratified silt loam and silty clay loam lacustrine sediments.
GEOGRAPHIC SETTING: Elpaso soils are on nearly level to level areas of till plains and moraines of Wisconsinan Age. Slope gradients range from 0 to 2 percent. The soils formed in 102 to 152 cm (40 to 60 inches) of loess and the underlying calcareous glacial till. Mean annual air temperature ranges from 10 to 12 degrees C (50 to 55 degrees F), mean annual precipitation ranges from 810 to 1020 mm (32 to 40 inches), frost-free period ranges from 140 to 180 days, and elevation ranges from 195 to 311 meters (640 to 1,020 feet) above the mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Andres, Chenoa, Dana, Elliott, Flanagan, Graymont, Lisbon, Raub, Saybrook, Symerton, and Varna soils. The somewhat poorly drained Andres and moderately well drained Symerton soils formed in loamy outwash and in the underlying silty clay loam glacial till. The somewhat poorly drained Chenoa and moderately well drained Graymont soils formed in 51 to 102 cm (20 to 40 inches) of loess and the underlying silty clay loam glacial till. The moderately well drained Dana and somewhat poorly drained Raub soils formed in 20 to 40 inches (51 to 102 cm) of loess and the underlying loam till with carbonates deeper than 107 cm (42 inches). The somewhat poorly drained Elliott and moderately well drained Varna soils formed in thin loess and silty clay loam till. The somewhat poorly drained Flanagan soils formed in 102 to 152 cm (40 to 60 inches) of loess and the underlying silt loam, loam, or silty clay loam till. The somewhat poorly drained Lisbon and moderately well drained Saybrook soils formed in 51 to 102 cm (20 to 40 inches) of loess and the underlying silt loam or loam till with carbonates shallower than 107 cm (42 inches). These associated soils are on adjoining higher elevations.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. The potential for surface runoff is low. Permeability is moderate in the loess and moderately slow in the glacial till. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/s) in the loess and moderately high (1.41 to 4.23 micrometers/s) in the glacial till. In undisturbed areas, the depth to an apparent seasonal high water table is 0.5 foot (15 cm) above the surface to 46 cm (1.5 feet) below the surface, commonly during the late winter and spring, in most years.
USE AND VEGETATION: Most areas are artificially drained and used for cultivated crops. Principal crops are corn and soybeans and other crops include small grain. Native vegetation is commonly marsh grasses and sedges.
DISTRIBUTION AND EXTENT: Central and northern Illinois. Includes areas previously mapped Drummer till substratum phase. Extent is moderate in MLRA 108A.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Woodford County, Illinois, 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
mollic epipedon - the zone from the surface to a depth of about 21 inches (53 cm) (Ap and A horizons);
cambic horizon - the zone from approximately 21 to 69 inches (53 to 175 cm) (Bg, Btg1, 2Btg2, 2Btg3 horizons);
aquic soil moisture regime. In some pedons there is a zone at the boundary between loess and till composed of strata or reworked glacial till which contains less clay and more sand, and varies in thickness.