LOCATION GRAYMONT                IL

Established Series
Rev. SKH-SLE-DEC
12/2015

GRAYMONT SERIES

The Graymont series consists of very deep, moderately well drained soils formed in loess and the underlying till on till plains. Slope ranges from 2 to 10 percent. Mean annual precipitation is about 940 mm (37 inches), and mean annual air temperature is about 10 degrees C (50 degrees F).

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 to 24 inches); yellowish brown (10YR 5/4) and yellowish brown (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 yellowish brown (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 1.5 miles southwest of Flanagan; 100 feet east and 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:
Depth to the base of soil development: 61 to 114 cm (24 to 45 inches)
Thickness of the mollic epipedon: 25 to 51 cm (10 to 20 inches)
Average clay content of the particle-size control section: 27 to 35 percent
Depth to till (horizons with sand content greater than 10 percent): 51 to 102 cm (20 to 40 inches)
Depth to carbonates: 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: 9 to 13 degrees C (48 to 56 degrees F)

Ap, A, and/or AB horizons:
Hue: 10YR
Value: 2 or 3
Chroma: 1 to 3
Texture: silt loam or silty clay loam
Sand content: 0 to 10 percent
Clay content: 22 to 33 percent
Reaction: slightly acid or neutral

Some pedons have a BA horizon instead of an AB horizon.
Bt horizon:
Hue: 10YR or 2.5Y
Value: 4 to 6
Chroma: 3 or 4
Texture: commonly silty clay loam but includes thin subhorizons of silt loam or silty clay
Sand content: 0 to 10 percent
Clay content: 25 to 35 percent
Reaction: moderately acid to neutral

2Bt, 2Btg, 2BC, and/or 2BCg horizons:
Hue: 10YR or 2.5Y
Value: 4 to 6
Chroma: 1 to 6
Texture: silty clay loam or silt loam, but includes thin subhorizons of silty clay
Sand content: 10 to 20 percent
Clay content: 22 to 40 percent
Silt content: greater than 50 percent
Rock fragment content: less than 15 percent
Reaction: neutral to moderately alkaline and some pedons contain carbonates.

The 2Cg or 2C horizon:
Hue: 10YR, 2.5Y, or 5Y
Value: 4 to 6
Chroma: 1 to 6
Texture: silty clay loam or silt loam
Sand content: 10 to 20 percent
Clay content: 24 to 34 percent
Silt content: averages more than 50 percent
Rock fragment content: less than 15 percent
Reaction: slightly alkaline or moderately alkaline and carbonates are present.

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 864 to 1067 mm (34 to 42 inches), frost-free period ranges from 155 to 190 days, and elevation ranges from 164 to 285 meters (538 to 935 feet) above sea level.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Andres, Ashkum, Chenoa, Elpaso, 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 and Elpaso 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, 110, and 115C.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) 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 108A 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: 0 to 30 cm (0 to 12 inches) (Ap and AB horizons)
argillic horizon: 30 to 97 cm (12 to 38 inches) (Bt1, Bt2, Bt3, Bt4 and 2Btg horizons)
lithologic discontinuity - at a depth of 84 cm (33 inches) (contact between the Bt4 and 2Btg horizons).

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National Cooperative Soil Survey
U.S.A.