LOCATION GRAYMONT ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Argiudolls
TYPICAL PEDON: Graymont silt loam - on a gently sloping area in a cultivated field at an elevation of 215 meters (704 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 cm (0 to 7 inches); black (10YR 2/1) silt loam, dark gray (10YR 4/1) dry; moderate fine granular structure; friable; few very fine roots; slightly acid; abrupt smooth boundary.
AB--18 to 30 cm (7 to 12 inches); very dark brown (10YR 2/2) silt loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure parting to moderate fine granular; friable; few very fine roots; slightly acid; clear smooth boundary. [Combined thickness of the A horizon is 25 to 51 cm (10 to 20 inches).]
Bt1--30 to 48 cm (12 to 19 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate fine angular blocky structure; friable; few very fine roots; common distinct very dark grayish brown (10YR 3/2) organo-clay films on faces of peds; few distinct brown (10YR 4/3) clay films on faces of peds; slightly acid; clear smooth boundary.
Bt2--48 to 61 cm (19 to24 inches); yellowish brown (10YR 5/4 and 10YR 5/6) silty clay loam; moderate fine prismatic structure parting to moderate fine angular blocky; friable; few very fine roots; common distinct brown (10YR 4/3) clay films on faces of peds; slightly acid; clear smooth boundary.
Bt3--61 to 71 cm (24 to 28 inches); yellowish brown (10YR 5/4 and 10YR 5/6) silty clay loam; moderate fine prismatic structure parting to moderate fine angular blocky; friable; few very fine roots; few distinct dark grayish brown (10YR 4/2) clay films on faces of peds; few fine black (7.5YR 2.5/1) very weakly cemented iron-manganese concretions throughout; common fine distinct grayish brown (10YR 5/2) iron depletions in the matrix; slightly acid; clear smooth boundary.
Bt4--71 to 84 cm (28 to 33 inches); brown (10YR 5/3) silt loam; weak fine prismatic structure parting to moderate fine angular blocky; friable; few very fine roots; few distinct grayish brown (10YR 5/2) clay films on faces of peds; few fine black (7.5YR 2.5/1) very weakly cemented iron-manganese concretions throughout; common fine distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common fine faint light brownish gray (10YR 6/2) iron depletions in the matrix; neutral; clear smooth boundary. [Combined thickness of the Bt horizon is 38 to 56 cm (15 to 22 inches).]
2Btg--84 to 97 cm (33 to 38 inches); grayish brown (2.5Y 5/2) silty clay loam; weak fine prismatic structure; firm; few very fine roots; few distinct dark grayish brown (2.5Y 4/2) clay films on faces of peds; few fine black (7.5YR 2.5/1) very weakly cemented iron-manganese concretions throughout; common fine distinct light olive brown (2.5Y 5/4) masses of oxidized iron in the matrix; 3 percent gravel; neutral; clear smooth boundary. [13 to 25 cm (5 to 10 inches) thick]
2Cg--97 to 152 cm (38 to 60 inches); grayish brown (2.5Y 5/2) silty clay loam; massive; firm; few fine black (7.5YR 2.5/1) very weakly cemented concretions of iron and manganese oxides throughout; few fine white (10YR 8/1) very weakly cemented calcium carbonate concretions throughout; few fine prominent light olive brown (2.5Y 5/6) masses of oxidized iron in the matrix; few fine faint light brownish gray (2.5Y 6/2) iron depletions in the matrix; 3 percent gravel; strongly effervescent; moderately alkaline.
TYPE LOCATION: Livingston County, Illinois; about 2.4 kilometers (1.5 miles) southwest of Flanagan; 30 meters (100 feet) east and 640 meters (2,100 feet) north of the southwest corner of sec. 28, T. 28 N., R. 3 E.; USGS Flanagan Southwest topographic quadrangle; lat. 40 degrees 51 minutes 41 seconds N. and long. 88 degrees 53 minutes 30 seconds W., NAD 27; UTM Zone 16, 340565 easting and 4525111 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development ranges from 61 to 114 cm (24 to 45 inches). The thickness of the mollic epipedon ranges from 25 to 51 cm (10 to 20 inches). The particle-size control section averages between 27 and 35 percent clay. Rock fragment content is less than 15 percent in the series control section. The thickness of loess (sand content less than 10 percent) and the depth to till (horizons with sand content greater than 10 percent) range from 51 to 102 cm (20 to 40 inches). The depth to carbonates is less than 102 cm (40 inches) and generally is a few inches less than the depth to the base of the argillic horizon. Mean annual soil temperature ranges from 9 to 13 degrees C (48 to 56 degrees F).
The Ap, A, or AB horizon has hue of 10YR, value of 2 or 3, and chroma of 1 to 3. It is silt loam or silty clay loam. Sand content ranges from 0 to 10 percent and clay content ranges from 22 to 33 percent. Reaction is slightly acid or neutral.
Some pedons have a BA horizon instead of an AB horizon.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 3 or 4. It dominantly is silty clay loam, but thin subhorizons are silt loam or silty clay. Sand content ranges from 0 to 10 percent and clay content ranges from 25 to 35 percent. Reaction ranges from moderately 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. It dominantly is silty clay loam or silt loam, but some thin subhorizons are silty clay. Sand content ranges from 10 to 20 percent and clay content ranges from 22 to 40 percent. Silt content averages more than 50 percent. Reaction ranges from neutral to moderately alkaline and some pedons contain carbonates.
The 2Cg or 2C horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 1 to 6. It is silty clay loam or silt loam. Sand content ranges from 10 to 20 percent and clay content ranges from 24 to 34 percent. Silt content averages more than 50 percent. Reaction is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Assumption, Aviston, Barrington, Blackberry, Buckhart, Catlin, Clare, Dana, Danabrook, Geryune, Harrison, Keltner, Saybrook, and Totanang soils. Assumption, Dana, Danabrook, Geryune, and Saybrook soils average less than 50 percent silt and contain more than 20 percent sand in the lower part of the series control section. Aviston soils have a mean annual soil temperature of more than 13 degrees C (56 degrees F). Barrington and Clare soils have subhorizons that contain more than 20 percent sand in the lower part of the series control section. Blackberry, Catlin, and Harrison soils average less than 10 percent sand in all parts above a depth of 102 cm (40 inches). Buckhart soils average less than 7 percent sand throughout the series control section. Keltner soils have a lithic contact within a depth of 152 cm (60 inches). Totanang soils have more than 15 percent rock fragments in the lower part of the series control section.
GEOGRAPHIC SETTING: Graymont soils have convex slopes on relatively undissected parts of till plains of Wisconsinan Age. Slope gradients range from 0 to 10 percent. The soils formed in 51 to 102 cm (20 to 40 inches) of loess and in the underlying calcareous silty till. 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 160 to 180 days, and elevation ranges from 165 to 285 meters (540 to 935 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Andres, Ashkum, Chenoa, Symerton, and Varna soils. The somewhat poorly drained Andres soils and the moderately well drained Symerton soils formed in loamy outwash and in the underlying till. The poorly drained Ashkum soils and the somewhat poorly drained Chenoa soils are on adjacent, lower lying parts of the landscape. Varna soils are on adjacent side slopes and formed in less than 51 cm (20 inches) of loess and the underlying till. Ashkum, Chenoa, and Varna soils are in the fine particle-size class.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. An intermittent perched seasonal high water table is at a depth of 61 to 107 cm (2.0 to 3.5 feet) at some time between February and April in most years. The potential for surface runoff is low to high. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/s) in the loess and moderately low to moderately high (0.42 to 1.41 micrometers per second) in the till. Permeability is moderate in the loess and slow in the till.
USE AND VEGETATION: Most areas are used for cultivated crops. Corn, soybeans, small grain, and meadow are the principal crops. Native vegetation is prairie grass.
DISTRIBUTION AND EXTENT: Central and east-central Illinois. Extent is moderate in MLRAs 108A and 110.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Livingston County, Illinois, 1990.
REMARKS: Saybrook soils correlated in east-central Illinois formed in silty till as part of the same Wisconsin glacial moraine as the Graymont soils. MLRA 108 and 110 update activities should determine the feasibility of correlating geographic separations of loam and clay loam till (< 50% silt) to Saybrook soils and silt loam and silty clay loam till (> 50% silt) to the Graymont series.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from 0 to 30 cm (0 to 12 inches) (Ap and AB horizons); argillic horizon - the zone from 30 to 97 cm (12 to 38 inches) (Bt1, Bt2, Bt3, Bt4 and 2Btg horizons).