LOCATION BIRKBECK IL+IN OHEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Hapludalfs
TYPICAL PEDON: Birkbeck silt loam - on a convex slope of 2 percent with a south-east aspect in a sparsely wooded area at an elevation of about 680 feet above mean sea level. (Colors are for moist soil unless otherwise stated.)
A--0 to 10 cm (0 to 4 inches); very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak thin platy structure parting to moderate very fine granular; friable; slightly acid; abrupt smooth boundary. [ 8 to 13 cm (3 to 5 inches) thick]
E--10 to 23 cm (4 to 9 inches); brown (10YR 4/3) silt loam; moderate very thin platy structure; friable; few distinct dark brown (10YR 3/3) organic coatings on faces of peds; few distinct gray (10YR 6/1) (dry) silt coatings on faces of peds; very strongly acid; clear smooth boundary. [ 0 to 2. cm (0 to 8 inches) thick]
Bt1--23 to 33 cm (9 to 13 inches); dark yellowish brown (10YR 4/4) silty clay loam; weak fine subangular blocky structure parting to moderate very fine granular; friable; common distinct dark brown (10YR 3/3) organo-clay films on faces of peds; common distinct light gray (10YR 7/1) (dry) silt coatings on faces of peds; few fine prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; strongly acid; clear smooth boundary.
Bt2--33 to 61 cm (13 to 24 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate fine and very fine subangular blocky structure; friable; many distinct brown (7.5YR 4/4) clay films on faces of peds; few fine prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; strongly acid; clear smooth boundary.
Bt3--61 to 74 cm (24 to 29 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate fine subangular blocky structure; friable; many distinct brown (7.5YR 4/4) clay films on faces of peds; common fine prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; strongly acid; clear smooth boundary.
Bt4--74 to 107 cm (29 to 42 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; friable; many distinct brown (7.5YR 4/4) clay films on faces of peds; few fine distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; common fine distinct light yellowish brown (2.5Y 6/4) masses of oxidized iron in the matrix; common medium prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; strongly acid; gradual smooth boundary.
Bt5--107 to 137 cm (42 to 54 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium and coarse subangular blocky structure; friable; many distinct brown (7.5YR 4/4) clay films on faces of peds; few fine distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; common fine distinct yellowish brown 2.5Y 6/4) iron-manganese accumulations and few medium distinct strong brown (7.5YR 5/6) masses of oxidized iron in the matrix; common medium prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; slightly acid; clear smooth boundary. [Combined thickness of the Bt horizon is 51 to 114 cm (20 to 45 inches).]
2Bt6--137 to 152 cm (54 to 60 inches); dark yellowish brown (10YR 4/4) loam; weak coarse subangular blocky structure; friable; few distinct brown (7.5YR 4/4) clay films on faces of peds; few distinct very dark grayish brown (10YR 3/2) organo-clay films in pores; common fine distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; common medium distinct light yellowish brown (2.5Y 6/4) iron-manganese accumulations and common fine distinct strong brown (7.5YR 5/6) masses of oxidized iron in the matrix; few fine prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; neutral; gradual smooth boundary. [ 10 to 51 cm (4 to 20 inches) thick]
2C--152 to 173 cm (60 to 68 inches); light olive brown (2.5Y 5/4) loam; massive; firm; few distinct very dark grayish brown (10YR 3/2) organo-clay films in pores; common fine distinct light brownish gray (2.5Y 6/2) iron depletions in the matrix; common fine faint light yellowish brown (2.5Y 6/4) and common fine distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; few fine prominent irregular black (7.5YR 2.5/1) weakly cemented iron-manganese nodules throughout; strongly effervescent; slightly alkaline.
TYPE LOCATION: Macon County, Illinois; about 7 miles northeast of Decatur; 1,600 feet east and 750 feet south of the northwest corner, sec. 25, T. 17 N., R. 3 E.; USGS Argenta, IL topographic quadrangle; latitude 39 degrees 54 minutes 25.2 seconds N., and longitude 88 degrees 48 minutes 59.9 seconds W., UTM Zone 16S 0344718 easting and 4419014 northing; NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 102 to 178 cm (40 to 70 inches). The depth to horizons with more than 15 percent sand ranges from 102 to 152 cm (40 to 60 inches). Soil development extends into the underlying material. The particle-size control section averages between 27 and 35 percent clay and less than 10 percent fine sand or coarser. The depth to carbonates ranges from 102 to 178 cm (40 to 70 inches).
The A horizon has hue of 10YR, value of 2 or 3, and chroma of 1 to 3. In cultivated pedons, the Ap horizon has hue of 10YR, value of 4 or 5, and chroma of 2 or 3. It is commonly silt loam. Clay content ranges from 15 to 27 percent. Reaction is strongly acid to neutral. In eroded soils, the Ap horizon may be silty clay loam with clay content ranging to 30 percent.
The E horizon has hue of 10YR, value of 4 or 5, and chroma of 2 to 4. It is silt loam and the clay content ranges from 15 to 27 percent. Reaction typically is very strongly acid to moderately acid, but ranges to neutral in pedons that have been limed.
The Bt horizon has hue of 10YR, value of 4 or 5, and chroma of 3 to 6. Clay films dominantly have chroma of 3 or 4. Redoximorphic features are in the middle and lower part of the Bt horizon. It is silt loam or silty clay loam. Clay content ranges from 25 to 40 percent. Reaction is very strongly acid to moderately acid in the most acid part, and ranges to neutral in some subhorizons in most pedons.
The 2Bt horizon has hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 6; and chroma of 2 to 8. It typically has redoximorphic features. It is loam, clay loam, silty clay loam, or silt loam. Clay content ranges from 20 to 35 percent and sand content ranges from 15 to 40 percent. It contains up to 15 percent by volume rock fragments. Reaction typically is slightly acid or neutral, but ranges from moderately acid to slightly alkaline.
Some pedons have a 2BC horizon.
The 2C horizon has hue of 10YR or 2.5Y, and less commonly 7.5YR; value of 4 to 6; and chroma of 2 to 4. It typically has redoximorphic features. It is loam, clay loam, silty clay loam, or silt loam, and contains 17 to 30 percent clay and 15 to 40 percent sand. It contains up to 15 percent by volume rock fragments. Reaction typically is slightly alkaline or moderately alkaline and contains carbonates, but in some pedons it is neutral in the upper part.
COMPETING SERIES: These are the Campton, Elco, Eleroy, Homen, Inton, Iona, Libre, Mayville, Minnith,m Morningsun, Redbud, Rocheport, Somonauk, Windere, Winfield, series. Campton soils have horizons with more than 40 percent sand in the lower part of the series control section. Elco, Libre, Mayville, Minnith, and Somonauk soils have horizons with more than 15 percent sand within a depth of 40 inches. Homen, Inton, Iona, Redbud, and Winfield soils have less than 15 percent sand in the lower part of the control section. Morningsun soils typically average more than 40 percent sand in the lower part of the series control section. Rocheport soils have a lithic or paralithic contact within a depth of 60 inches and have more than 35 percent clay in the 2Bt horizon. Zurich soils have carbonates within a depth of 40 inches.
GEOGRAPHIC SETTING: Birkbeck soils are on till plains of Wisconsinan Age. Slope gradients commonly are between 1 and 10 percent, but range from 0 to 18 percent. Birkbeck soils formed in 40 to 60 inches of loess and in the underlying calcareous loamy till. Mean annual air temperature ranges from 45 to 55 degrees F., mean annual precipitation ranges from 29 to 40 inches, frost-free period ranges from 155 to 180 days, and elevation ranges from 500 to 1350 feet above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Dodge,
Fayette,
Kendall,
Miami,
Reesville,
Rozetta,
Russell,
Sabina,
St. Charles,
Senachwine,
Sunbury, and
Xenia soils. The well drained Dodge, Russell, and Senachwine soils, and the moderately well drained Miami soils are on similar nearby landscapes that have a thinner mantle of loess. The well drained Fayette and Rozetta soils generally are up slope on summits or nearer the center of interstream divides where the loess is thicker. The somewhat poorly drained Kendall and well drained St. Charles soils commonly are at lower elevations and have the lower part of their sola formed in loamy outwash. The somewhat poorly drained Reesville and Sunbury soils are on similar parts of the landscape nearby. They both have gray colors higher in the sola and, in addition, Sunbury soils have a surface horizon between 7 and 10 inches in thickness that have moist color value of 3 or less and contain more clay in the control section. The somewhat poorly drained Sabina soils are on more nearly level parts of the landscape nearby and form a drainage sequence
with Birkbeck soils. The moderately well drained Xenia soils are on similar parts of the landscape nearby.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. An perched seasonal high water table is at a depth of 2 to 3.5 feet at some time between February and April in normal years. The potential for surface runoff is low to medium. Saturated hydraulic conductivity is is moderately high to high (4.23 to 14.11 micrometer per second). Permeability is moderate.
USE AND VEGETATION: Some areas are in woodland, some are in pasture, and some in cropland. Corn, soybeans, small grain, and meadow are the principal crops. Native vegetation is deciduous forest.
DISTRIBUTION AND EXTENT: MLRA 108 and 111 in central and northern Illinois, Indiana, and southwestern Ohio. The extent is moderate.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: De Witt County, Illinois, 1936.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 9 inches (A and E horizons);
argillic horizon - the zone from about 9 to 60 inches (Bt1, Bt2, Bt3, Bt4, Bt5, 2Bt6 horizons);
lithologic discontinuity from loess to till at a depth of 54 inches;
ADDITIONAL DATA: NSSL data is available on 4 horizons of the typical pedon (pedon no. S80IL-115-035).