LOCATION MILLBROOK IL+INEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Udollic Endoaqualfs
TYPICAL PEDON: Millbrook silt loam - on a 1 percent slope in a cultivated field at an elevation of 201 meters (660 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 cm (0 to 7 inches); very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine and medium granular structure; friable; few fine rounded black (7.5YR 2.5/1) very weakly cemented iron-manganese nodules throughout; neutral; abrupt smooth boundary. [18 to 23 cm (7 to 9 inches) thick]
E--18 to 36 cm (7 to 14 inches); dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; weak medium platy structure parting to moderate medium granular; friable; many distinct very dark gray (10YR 3/1) organic coatings on faces of peds; few fine rounded black (7.5YR 2.5/1) very weakly cemented iron-manganese nodules throughout; many fine faint brown (10YR 4/3) extremely weakly cemented iron-manganese accumulations and few fine prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; neutral; clear smooth boundary. [8 to 30 cm (3 to 12 inches) thick]
Bt--36 to 53 cm (14 to 21 inches); yellowish brown (10YR 5/6) silty clay loam; moderate fine subangular blocky structure; friable; few distinct dark gray (10YR 4/1) clay films on faces of peds and on surfaces along pores; few medium irregular black (7.5YR 2.5/1) very weakly cemented iron-manganese nodules throughout; few fine distinct yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; common medium prominent grayish brown (10YR 5/2) iron depletions in the matrix; moderately acid; clear smooth boundary.
Btg1--53 to 89 cm (21 to 35 inches); 70 percent gray (10YR 5/1) and 30 percent yellowish brown (10YR 5/6) silty clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; few distinct dark gray (10YR 4/1) clay films on faces of peds and on surfaces along pores; common medium irregular black (7.5YR 2.5/1) very weakly cemented iron-manganese nodules throughout; moderately acid; clear smooth boundary. [Combined thickness of the Bt and Btg horizons is 20 to 64 cm (8 to 25 inches)].
2Btg2--89 to 112 cm (35 to 44 inches); gray (10YR 5/1) clay loam; moderate medium prismatic structure; friable; few distinct dark gray (10YR 4/1) clay films on faces of peds; few distinct very dark gray (10YR 3/1) organo-clay films on surfaces along pores; few medium irregular black (7.5YR 2.5/1) very weakly cemented iron-manganese nodules throughout; many coarse prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; slightly acid; clear smooth boundary. [10 to 38 cm (4 to 15 inches) thick]
2BCg--112 to 140 cm (44 to 55 inches); 60 percent gray (10YR 5/1) and 40 percent yellowish brown (10YR 5/4) stratified clay loam and sandy loam; weak medium prismatic structure; friable; few medium irregular black (7.5YR 2.5/1) iron-manganese coatings on faces of peds; common medium prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; 10 percent fine gravel in clay loam strata; neutral; clear smooth boundary. [0 to 28 cm (0 to 11 inches) thick]
2Cg1--140 to 185 cm (55 to 73 inches); 60 percent gray (10YR 5/1) and 40 percent yellowish brown (10YR 5/4) sandy loam stratified with thin lenses of coarse sand; massive; very friable; 5 percent fine gravel; neutral; abrupt smooth boundary.
2Cg2--185 to 203 cm (73 to 80 inches); 60 percent pale brown (10YR 6/3) and 40 percent light brownish gray (10YR 6/2) sandy loam; massive; very friable; 5 percent fine gravel; slightly effervescent; slightly alkaline.
TYPE LOCATION: Champaign County, Illinois; near the Champaign-Douglas county line about 15 miles (24.1 kilometers) south and 3 1/2 miles (5.6 kilometers) east of Urbana; 55 feet (16.8 meters) north and 2,240 feet (682.8 meters) west of the southeast corner of sec. 36, T. 17 N., R. 9 E.; USGS Villa Grove NW, Illinois topographic quadrangle; lat. 39 degrees 52 minutes 49 seconds N. and long. 88 degrees 7 minutes 51 seconds W.; NAD 27; UTM Zone 16, 403299 easting and 4415085 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of argillic horizon ranges from 102 to 152 cm (40 to 60 inches) in thickness. Depth to carbonates is greater than 102 cm (40 inches). The depth to horizons averaging more than 15 percent sand ranges from 61 to 102 cm (24 to 40 inches). The particle-size control section averages between 25 and 35 percent clay.
The Ap or A horizon has hue of 10YR, value of 2 or 3 (4 or 5 dry), and chroma of 1 to 3. It is silt loam. Reaction ranges from strongly acid to slightly alkaline depending upon liming practices.
The E horizon has hue of 10YR, value of 4 to 6, and chroma of 2 or 3. It is silt loam. Reaction ranges from strongly acid to neutral.
A BE horizon is present in some pedons.
The Bt or Btg horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 1 to 6. It is silty clay loam or silt loam. Reaction ranges from strongly acid to neutral.
The 2Bt, 2Btg, 2BC, or 2BCg horizon) has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 1 to 6. Texture is sandy loam, sandy clay loam, loam, or clay loam but includes thin strata of sand or silt loam in some pedons. Clay content averages between 18 and 35 percent and sand content averages between 20 and 60 percent. Content of rock fragments is less than 15 percent. Reaction in the 2Bt or 2Btg horizon ranges from strongly acid to neutral. Reaction in the 2BC or 2BCg horizon ranges from strongly acid to slightly alkaline.
The 2C or 2Cg horizon has hue of 7.5YR, 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 to 8. It is typically stratified. Textures are dominantly sandy loam, loam, clay loam, sandy clay loam, or silt loam, but include thin strata of loamy sand, sand, or coarse sand. Clay content averages between 10 and 25 percent and sand content averages between 20 and 70 percent. Content of rock fragments is less than 15 percent. Reaction ranges from moderately acid to moderately alkaline.
COMPETING SERIES: These are the Atterberry, Bethalto, Canoe, Curran, Emery, Franklin, Koszta, Mulvey, Virgil, and Wauconda series. Atterberry, Bethalto, Canoe, and Koszta soils have less than 20 percent sand in the lower part of the series control section. Curran soils average more than 70 percent sand in the lower part of the series control section. Emery soils are not stratified with textures containing as much as 70 percent sand in the lower part of the series control section. Franklin soils do not have stratified silty and loamy horizons within the series control section. Mulvey soils have greater than 15 percent rock fragments in the lower part of the series control section. Virgil soils do not have horizons with more than 20 percent sand within a depth of 102 cm (40 inches). Wauconda soils contain carbonates within a depth of 102 cm (40 inches).
GEOGRAPHIC SETTING: Millbrook soils are on outwash plains and stream terraces. Slope ranges from 0 to 5 percent. Millbrook soils formed in 61 to 102 cm (24 to 40 inches) of loess or other silty material and in the underlying loamy stratified outwash. Mean annual air temperature ranges from 8 to 12 degrees C (46 to 54 degrees F), mean annual precipitation ranges from 740 to 1020 mm (29 to 40 inches), frost-free period ranges from 140 to 190 days, and elevation ranges from 122 to 311 meters (400 to 1020 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beardstown, Brenton, Drummer, Elburn, Harvard, Sexton, Starks, and Virgil soils. Beardstown, Brenton, Elburn, Starks, and Virgil soils are nearby on similar landscape positions. Brenton and Starks soils form a biosequence with Millbrook soils. The poorly drained Drummer soils and the well drained Harvard soils form a drainage sequence with Millbrook soils. Drummer soils are on lower parts of the landscape and Harvard soils are on adjoining higher elevations. The poorly drained Sexton soils form a drainage sequence with Millbrook soils near forested areas and are on lower parts of the landscape.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. An intermittent apparent seasonal high water table is at a depth of 0.5 to 2.0 feet (13 to 61 cm) at some time between January and May in most years. The potential for surface runoff is low or medium. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/s). Permeability is moderate.
USE AND VEGETATION: Most areas are used to grow corn and soybeans. Some areas are used for growing small grain or meadow. Native vegetation is prairie grass and widely spaced trees.
DISTRIBUTION AND EXTENT: Central and northern Illinois. The extent is moderate in MLRAs 95B, 108A, 108B, 110, 111D, and 114.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Kendall County, Illinois, 1940.
REMARKS: A till substratum phase is recognized. It will be investigated during MLRA update activities. Possibly a new soil series will be established, and a new data map unit will be developed.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 36 cm (14 inches) (Ap and E horizons);
argillic horizon- the zone from approximately 36 to 112 cm (14 to 44 inches) (Bt, Btg1, and 2Btg2 horizons);
aquic conditions - endosaturation implied by redoximorphic features present in the zone from 18 to 203 cm (7 to 80 inches) (E, Bt, Btg1, 2Btg2, 2BCg, 2Cg1, and 2Cg2 horizons); mesic temperature regime.
ADDITIONAL DATA: University of Illinois Pedology Laboratory sample numbers 22279 to 22288 in DeKalb County and 20962 to 20970 in Stephenson County.