LOCATION PLUMFIELD ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Aquic Fragiudalfs
TYPICAL PEDON: Plumfield silty clay loam - on an 8 percent slope in a grass-legume field at an elevation of about 122 meters (400 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 13 cm (0 to 5 inches); yellowish brown (10YR 5/4) silty clay loam, light yellowish brown (10YR 6/4) dry; weak fine granular structure; friable; common very fine and fine roots throughout; very strongly acid; abrupt smooth boundary. [10 to 23 cm (4 to 9 inches) thick]
Btx1--13 to 18 cm (5 to 7 inches); yellowish brown (10YR 5/6) silty clay loam; strong thick platy structure parting to strong medium platy; very firm; few very fine roots between peds; few faint dark yellowish brown (10YR 4/6) clay films on faces of peds and in pores; common fine prominent spherical very dark gray (10YR 3/1) extremely weakly cemented iron-manganese accumulations; brittle; extremely acid; abrupt smooth boundary. [0 to 28 cm (0 to 11 inches) thick]
2Btx2--18 to 30 cm (7 to 12 inches); yellowish brown (10YR 5/6) silty clay loam; moderate medium prismatic structure parting to weak medium subangular blocky; very firm; few very fine roots between peds; common faint grayish brown (10YR 5/2) and brown (10YR 5/3) clay films on faces of peds and in pores; few prominent white (10YR 8/1) silt coats on faces of peds and in pores; common fine and medium prominent grayish brown (10YR 5/2) iron depletions in the matrix; common fine prominent spherical very dark gray (10YR 3/1) extremely weakly cemented iron-manganese accumulations; brittle; extremely acid; clear smooth boundary.
2Btx3--30 to 91 cm (12 to 36 inches); yellowish brown (10YR 5/6) silt loam; weak very coarse prismatic structure; very firm; few very fine roots between peds; few faint dark yellowish brown (10YR 4/6) clay films on faces of peds and in pores; common fine prominent grayish brown (10YR 5/2) iron depletions in the matrix; common fine prominent spherical very dark gray (10YR 3/1) extremely weakly cemented iron-manganese accumulations; 1 percent pebbles (igneous); brittle; very strongly acid; gradual smooth boundary. [The combined thickness of the 2Bxt horizons is 56 to 127 cm (22 to 50 inches) thick]
3Btgb1--91 to 117 cm (36 to 46 inches); grayish brown (10YR 5/2) silty clay loam; moderate coarse and medium prismatic structure parting to moderate medium angular blocky; very firm; few distinct dark yellowish brown (10YR 4/6) and few faint brown (10YR 5/3) and gray (10YR 5/1) clay films on faces of peds and in pores; many fine and medium prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common fine faint irregular very dark gray (10YR 3/1) extremely weakly cemented iron-manganese accumulations; common fine irregular barite crystals; 1 percent gravel; strongly acid; gradual smooth boundary.
3Btgb2--117 to 142 cm (46 to 56 inches); grayish brown (10YR 5/2) silty clay loam; weak coarse prismatic structure; very firm; few distinct dark yellowish brown (10YR 4/6) and few faint brown (10YR 5/3) and gray (10YR 5/1) clay films on faces of peds and in pores; many fine and medium prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common fine faint irregular very dark gray (10YR 3/1) extremely weakly cemented iron-manganese accumulations; common fine irregular barite crystals; 1 percent gravel; moderately acid; gradual smooth boundary.
3Btgb3--142 to 178 cm (56 to 70 inches); grayish brown (10YR 5/2) silty clay loam; weak very coarse prismatic structure; very firm; common faint gray (10YR 5/1) and brown (10YR 5/3) pores and few distinct dark yellowish brown (10YR 4/6) clay films on faces of peds and in pores; many fine and medium prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; many fine and medium faint irregular very dark gray (10YR 3/1) extremely weakly cemented iron-manganese accumulations; common fine irregular barite crystals; 1 percent gravel; slightly acid.
TYPE LOCATION: Franklin County, Illinois; about 500 feet east and 2,060 feet south of the northwest corner of sec. 18, T. 7 S., R. 2 E.; USGS Christopher, IL topographic quadrangle; lat. 37 degrees 54 minutes 56 seconds N. and long. 89 degrees 2 minutes 15 seconds W.; UTM Zone 16, Easting 320900 and Northing 4198402; NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the Peoria loess: 0 to 51 centimeters (0 to 20 inches)
Depth to the fragipan: 13 to 51 centimeters (5 to 20 inches)
Depth to the base of soil development and bedrock: More than 152 centimeters (60 inches)
Ap horizon:
Hue=10YR
Value=4 or 5
Chroma=2 to 4
Texture=silty clay loam or silt loam
Clay content=averages 20 to 35 percent
Sand content=averages 2 to 15 percent
Reaction=very strongly acid to neutral
Btx horizon:
Hue=10YR
Value=4 to 6
Chroma=2 to 8
Texture=silt loam or silty clay loam
Clay content=averages 20 to 30 percent
Sand content=averages 2 to 15 percent
Reaction= extremely acid to moderately acid
2Btx horizon:
Hue=10YR
Value=4 to 6
Chroma=2 to 8
Texture=silt loam, silty clay loam, or loam
Clay content=averages 20 to 30 percent
Sand content=averages 10 to 25 percent
Rock fragment content=0 to 3 percent
Reaction=extremely acid to strongly acid
3Btg horizon:
Hue=10YR or 7.5YR
Value=4 to 6
Chroma=1 or 2
Texture=loam, silt loam, clay loam, or silty clay loam
Clay content=averages 20 to 35 percent
Sand content=averages 15 to 35 percent
Rock fragment content=1 to 10 percent
Reaction=extremely acid to slightly acid
COMPETING SERIES: These are the Boston, Chalfont, Gudgel, Haubstadt, Nabb, Pierpont, Robbs, Sciotoville and Shakamak series. Boston soils have limestone fragments and a reaction of neutral or higher in the lower part of the series control section. Chalfont soils have more than 10 percent rock fragments of shale in the lower part of the series control section. Gudgel soils have a paralithic contact within a depth of 152 cm (60 inches). Haubstadt, Nabb, Robbs and Shakamak soils are more than 51 centimeters (20 inches) to the top of the fragipan. Pierpont soils are less than 152 cm (60 inches) to the base of the soil development and have a reaction of neutral or higher in the lower part of the series control section. Sciotoville soils formed in old alluvium on stream terraces, typically contain mica flakes and a have an argillic horizon that is not part of the fragipan or fragic layers in the upper part of the series control section.
GEOGRAPHIC SETTING: Plumfield soils are on actively degrading positions on side slopes. They formed in less than 51 centimeters (20 inches) of Peorian loess (sand content less than about 8 percent); in 51 to 127 centimeters of Roxana silts (sand content 10 to 30 percent); and a mix of Roxana silts and glacial drift (20 to 50 inches) and in weathered Illinoian glacial till to depths greater than 152 centimeters (60 inches). In most cases a strongly developed Sangamon geosol occurs in the glacial till or drift. Slopes range from 5 to 18 percent. Mean annual air temperature ranges from 12 to 14 degrees C (54 to 57 degrees F), mean annual precipitation ranges from 1067 to 1219 millimeters (42 to 48 inches), frost free days range from 180 to 210, and elevation ranges from 152 to 229 meters (500 feet to 750 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Atlas, Ava, Blair, and Hickory soils. Atlas, Blair, and Hickory soils do not have fragipans. Atlas and Hickory soils are stratigraphically lower than Plumfield soils. Ava soils are on shoulders and crests above the Plumfield soils.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. A perched, seasonal water table is at a depth of 46 to 107 centimeters (1.5 to 3.5 feet) from January through April in most years. Saturated hydraulic conductivity is low or moderately low (0.07 to 0.42 micrometers/sec) in the fragipan or in horizons with fragic soil properties and moderately low to moderately high (0.42 to 1.41 micrometers/sec) below the fragipan. Permeability is very slow in the fragipan or in horizons with fragic soil properties and slow or moderately slow below the fragipan. The potential for surface runoff is medium or high.
USE AND VEGETATION: Most areas are cultivated. Corn, grain sorghum, soybeans, and wheat are commonly grown. Some areas are used for forage production. Native vegetation is oak-hickory forest.
DISTRIBUTION AND EXTENT: Southern Illinois. The extent is small.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Franklin County, Illinois, 1992.
REMARKS: Plumfield soils were previously mapped as severely eroded soils that were taxadjunct to the Ava series because they lacked an argillic horizon above the fragipan. Horizon designations become difficult to discuss in the range in characteristics section because of different possibilities of parent materials. Although not required as part of the series concept, most pedons described so far have a thin mantle of Peoria loess as the upper stratigraphic unit. The next stratigraphic unit (horizon designation prefix 2 in this pedon) is Roxana silt or a mix of Roxana silt and glacial drift. This material has its lower boundary at the contact with glacial till (presumably of Illinoian age). In most places the glacial till has evidence of prior soil development, the Sangamon soil. Many of the properties of this horizon (horizon designation prefix 3 in this pedon) are inherited from the paleosol. It is believed, however, that present pedogenic processes have resulted in some properties of the Plumfield soils being super-imposed on these horizons.
Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - the zone from the surface to a depth of 13 cm (5 inches), (Ap horizons); argillic horizon the zone from 13 to 178 cm (5 to 70 inches), (Btx1, 2Btx2, 2Btx3, 3Btgb1, 3Btgb2 and 3Btgb3); fragipan - the zone from 30 to 91 cm (12 to 36 inches), (2Btx3 horizon).