LOCATION SELMASS IL+IA MNEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Endoaquolls
TYPICAL PEDON: Selmass loam - on a nearly level, southwest-facing slope on an outwash plain in a cultivated field at an elevation of 254 meters (834 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 10 cm (0 to 4 inches); black (N 2.5/) loam, dark gray (10YR 4/1) dry; weak medium subangular blocky structure parting to weak medium granular; friable; common very fine roots; neutral; abrupt smooth boundary.
A--10 to 28 cm (4 to 11 inches); black (10YR 2/1) loam, dark gray (10YR 4/1) dry; weak fine and medium subangular blocky structure; friable; common very fine roots; common distinct black (N 2.5/) organic coats on faces of peds and in pores; neutral; clear smooth boundary. [Combined thickness of the A horizon is 25 to 51 cm (10 to 20 inches).]
AB--28 to 38 cm (11 to 15 inches); 65 percent black (10YR 2/1) and 35 percent very dark grayish brown (2.5Y 3/2) loam, dark grayish brown (10YR 4/2) dry; weak fine and medium subangular blocky structure; friable; common very fine roots; neutral; clear smooth boundary. [0 to 15 cm (0 to 6 inches) thick]
Btg1--38 to 51 cm (15 to 20 inches); dark grayish brown (2.5Y 4/2) loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; common very fine roots; few distinct dark gray (2.5Y 4/1) clay films and few distinct black (10YR 2/1) organic coats on faces of peds and in pores; common fine distinct olive brown (2.5Y 4/4) masses of iron accumulation in the matrix; common fine and medium faint grayish brown (2.5Y 5/2) iron depletions in the matrix; 1 percent gravel; neutral; gradual smooth boundary.
Btg2--51 to 76 cm (20 to 30 inches); grayish brown (2.5Y 5/2) clay loam; moderate medium subangular blocky structure; friable; common very fine roots; few distinct dark gray (2.5Y 4/1) and dark grayish brown (2.5Y 4/2) clay films on faces of peds and in pores; common fine strong brown (7.5YR 4/6) very weakly cemented iron oxide concretions throughout; common fine and medium distinct light olive brown (2.5Y 5/4) masses of iron accumulation in the matrix; 2 percent gravel; neutral; gradual smooth boundary.
Btg3--76 to 107 cm (30 to 42 inches); light olive gray (5Y 6/2) clay loam; weak medium and coarse subangular blocky structure; friable; few very fine roots; few distinct olive gray (5Y 5/2) clay films on faces of peds and in pores; common fine strong brown (7.5YR 4/6) very weakly cemented iron oxide concretions throughout; very dark gray (10YR 3/1) krotovina; common fine and medium distinct light olive brown (2.5Y 5/4) masses of iron accumulation in the matrix; 2 percent gravel; neutral; clear smooth boundary. [Combined thickness of the Btg horizon is 38 to 89 cm (15 to 35 inches).]
2BCg--107 to 119 cm (42 to 47 inches); grayish brown (2.5Y 5/2) sandy loam; weak medium subangular blocky structure; very friable; few very fine roots; common medium and coarse distinct light olive brown (2.5Y 5/4) masses of iron accumulation in the matrix; 4 percent gravel; neutral; clear wavy boundary. [0 to 25 cm (0 to 10 inches) thick]
2Cg--119 to 152 cm (47 to 60 inches); grayish brown (2.5Y 5/2) stratified sand and loamy sand; single grain; loose; common medium and coarse prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; 4 percent gravel; neutral.
TYPE LOCATION: McHenry County, Illinois, about 4 km (2.5 miles) northeast of Union; 15 m (50 feet) north and 183 m (600 feet) east of the southwest corner of sec. 23, T. 44 N., R. 6 E.; USGS Marengo North topographic quadrangle; lat. 42 degrees 16 minutes 11 seconds N., and long. 88 degrees 30 minutes 31 seconds W., NAD 27; UTM Zone 16, 375581 easting and 4680828 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development and the depth to horizons with more than 80 percent sand ranges from 89 to 140 cm (35 to 55 inches). The mollic epipedon ranges from 25 to 51 cm (10 to 20 inches) in thickness. Reaction ranges from moderately acid to slightly alkaline in the upper two parts of the series control section from slightly acid to moderately alkaline and in the lower two parts.
The upper part of the series control section (Ap, A, and/or AB horizon) has hue of 10YR, 2.5Y, or is neutral; value of 2 to 3; and chroma of 0 to 2. It is loam or clay loam and less commonly silt loam.
The second part of the series control section (Btg, BAg, and/or Bg 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 0 to 8. Texture is loam or clay loam, but some subhorizons are 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 20 to 50 percent.
The third part of the series control section (2Btg, 2Bg, and/or 2BCg horizon) has hue of 10YR, 2.5Y, or 5Y; value of 5 or 6; and chroma of 1 or 2. Redoximorphic features have chroma ranging from 1 to 8. Texture is sandy loam, loam, or loamy sand. The average clay content ranges from 10 to 20 percent, and the average sand content ranges from 40 to 75 percent. Gravel content ranges from 0 to 10 percent.
The lower part of the series control section (2Cg and/or 2C horizon) has hue of 10YR, 2.5Y, or 5Y; value of 5 or 6; and chroma of 1 to 6. It is sand or loamy sand. Sand content averages between 80 and 98 percent. The sand fraction is more than 50 percent medium and coarse sand. Gravel content ranges from 0 to 15 percent.
COMPETING SERIES: These are the Clyde, Faxon, Kossuth, Letri, Marengo, Mound Creek, Reddick, Selma, Tripoli, Webster, and Wolcott series. Clyde, Letri, Marengo, Kossuth, Reddick, Selma, Tripoli, Webster, and Wolcott soils average less than 80 percent sand in the lower part of the series control section Faxon and Mound Creek soils have a lithic contact within a depth of 102 cm (40 inches).
GEOGRAPHIC SETTING: The Selmass soils are on nearly level or slightly depressional parts of outwash plains and stream terraces. Slopes range from 0 to 2 percent. Selmass formed in loamy outwash overlying sandy sediments. The mean annual air temperature ranges from 7 to 12 degrees C (44 to 53 degrees F), the mean annual precipitation ranges from 737 to 1016 mm (29 to 40 inches), frost free days range from 140 to 180 days, and elevation ranges from 207 to 311 meters (680 to 1020 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dakota, Dickinson, Hoopeston, and Lahoguess soils. The well drained Dakota and Dickinson soils and the somewhat poorly drained Hoopeston and Lahoguess soils are on higher landform positions. Dickinson and Hoopeston soils are coarse-loamy.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. In drained conditions an intermittent apparent high water table is 15 cm (0.5 foot) above the surface to 46 cm (1.5 feet) below the surface in most years and in undrained conditions 15 cm (0.5 foot) above the surface to 30 cm (1.0 foot) below the surface. The potential for surface runoff is negligible. Saturated hydraulic conductivity is moderately high or high (4.23 to 42.33 micrometers per second) in the solum and high or very high (42.33 to 141.11 micrometers per second) in the underlying material. Permeability is moderate to moderately rapid in the solum and rapid in the underlying material. These soils are very rarely flooded or rarely flooded for very brief or brief duration on stream terraces. Very rarely flooded or rarely flooded phases of these soils that occur on stream terraces are recognized.
USE AND VEGETATION: Most areas are used to grow corn and soybeans. Native vegetation is hydrophytic grasses, reeds, and sedges.
DISTRIBUTION AND EXTENT: Northern Illinois, northeastern Iowa, and southeastern Minnesota. The extent is small in MLRAs 95B, 104, 105, 108A, 108B, and 110.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: McHenry County, Illinois, 1996. The name Selmass is derived from the Selma series with a sandy substratum.
REMARKS: This soil was formerly mapped Selma in McHenry County. Through MLRA update activities these units were found to average more than 80 percent sand in the lower part of the series control section whereas Selma soils average 30 to 80 percent.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon horizon - the zone from the surface to a depth of 38 cm (15 inches) (Ap, A, and AB horizons); cambic horizon - the zone from 38 to 119 cm (15 to 47 inches) (Btg1, Btg2, Btg3, and 2BCg horizons); discontinuity at a depth of 107 cm (42 inches) - the contact between the Btg3 and 2BCg horizons; aquic moisture regime - chroma of 2 in the matrix and redoximorphic features present in the zone from 38 to 152 cm (15 to 60 inches) (Btg1, Btg2, Btg3, 2BCg, and 2Cg horizons).