LOCATION COOT ILEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, mesic Aquic Argiudolls
TYPICAL PEDON: Coot loam - on a 1 percent slope in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 10 inches; very dark gray (10YR 3/1) loam, dark gray (10YR 4/1) dry; weak fine granular structure; friable; common very fine roots; neutral; clear smooth boundary.
A--10 to 15 inches; very dark gray (10YR 3/1) loam, dark gray (10YR 4/1) dry; weak fine and medium granular structure; friable; few very fine roots; neutral; clear smooth boundary. (Combined thickness of the A horizons is 10 to 20 inches.)
Bt1--15 to 19 inches; dark grayish brown (10YR 4/2) clay loam; weak fine subangular blocky structure; firm; few very fine roots; many distinct very dark gray (10YR 3/1) organo-clay films on faces of peds and lining pores; few fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation with diffuse boundaries lining pores and root channels; neutral; clear smooth boundary.
Bt2--19 to 22 inches; dark grayish brown (10YR 4/2) clay loam; moderate medium subangular blocky structure; firm; few very fine roots; common distinct very dark gray (10YR 3/1) organo-clay films on faces of peds and lining pores; about 5 percent fine pebbles; common fine distinct dark yellowish brown (10YR 4/6) masses of iron accumulation with diffuse boundaries lining pores and root channels; neutral; clear smooth boundary. (Combined thickness of the Bt horizons is 5 to 12 inches.)
2Bt3--22 to 27 inches; dark grayish brown (10YR 4/2) gravelly clay loam; moderate medium subangular blocky structure; firm; few distinct very dark gray (10YR 3/1) organo-clay films on faces of peds and lining pores; about 15 percent fine and medium, and less than 1 percent coarse pebbles; common medium distinct dark yellowish brown (10YR 4/6) and yellowish brown (10YR 5/8) masses of iron accumulation with diffuse boundaries lining pores and root channels; neutral; clear smooth boundary.
2Bt4--27 to 32 inches; dark grayish brown (10YR 4/2) gravelly clay loam; moderate medium subangular blocky structure; firm; few distinct very dark gray (10YR 3/1) organo-clay films lining root channels and pores; about 20 percent fine and medium, and 1 percent coarse pebbles; common medium distinct dark yellowish brown (10YR 4/6) and yellowish brown (10YR 5/8) masses of iron accumulation with diffuse boundaries lining ped surfaces and pores; slightly alkaline; clear smooth boundary. (Combined thickness of the 2Bt horizon is 6 to 13 inches.)
2C--32 to 41 inches; brown (10YR 5/3) and yellowish brown (10YR 5/4) gravelly loamy coarse sand; single grain; loose; about 30 percent fine and medium pebbles, and 3 percent coarse pebbles; slightly effervescent; slightly alkaline; abrupt smooth boundary. (5 to 15 inches)
3Cr--41 to 60 inches; (60%) light gray (N 6/0) and light brownish gray (2.5Y 6/2), and (40%) light olive brown (2.5Y 5/4) clay shale; massive with horizontal planes of cleavage; very firm; violently effervescent; slightly alkaline.
TYPE LOCATION: Fulton County, Illinois; about 3 miles south of Banner, 1998 feet east and 1132 feet south of the northwest corner of sec. 34, T. 6 N., R. 5 E.; USGS Duck Island topographic quadrangle; lat. 40 degrees 27 minutes 17 seconds N. and long. 89 degrees 55 minutes 40 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 20 to 40 inches. The mollic epipedon is 10 to 20 inches thick and extends into the upper part of the Bt horizon in some pedons. Depth to a paralithic contact in shale ranges from 40 to 60 inches. Rock fragments and coarse fragments in the outwash are primarily igneous. The particle size control section averages between 25 and 35 percent clay.
The upper part of the series control section (Ap and/or A horizons) has hue of 10YR, value of 2 or 3 and chroma of 1 or 2. It is commonly loam but includes clay loam. Content of rock fragments ranges from 0 to 5 percent. Reaction is slightly acid or neutral.
The middle part of the series control section (Bt, Btg, 2Bt, and/or 2Btg horizon) has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 8. Reaction ranges from slightly acid to moderately alkaline. The upper part (Bt or Btg) typically is clay loam but includes sandy clay loam. The lower part (2Bt or 2Btg) is gravelly clay loam, gravelly sandy clay loam or gravelly sandy loam. Redox concentrations are present throughout, commonly as masses of iron accumulation lining ped surfaces and pores. Content of rock fragments ranges from 0 to 15 percent in the Bt or Btg and 15 to 35 percent in the 2Bt or 2Btg horizon.
The lower part of the series control section to a depth of 41 inches (2C horizon) has hue of 10YR, value of 4 to 6 and chroma of 1 to 8. It commonly is gravelly loamy coarse sand but includes strata of gravel and sand. Content of rock fragments and coarse fragments ranges from 15 to 35 percent. The 2C horizon varies considerably in the proportion of sand and gravel. Some pedons contain stones. The lower 10 inches of the control section to a depth of 51 inches (3Cr horizon) is clayey shale. Reaction ranges from neutral to moderately alkaline.
COMPETING SERIES: Theses are the Fabius and Kane series. Fabius and Kane soils do not have a paralithic contact within a depth of 60 inches.
GEOGRAPHIC SETTING: The Coot soils are on broad summits of strath terraces. Slope ranges from 0 to 3 percent. These soils formed in 40 to 60 inches of loamy outwash and the underlying calcareous gravel and sand. Cobbles, stones and a few boulders are evident on eroded risers. Mean annual temperature ranges from 50 to 54 degrees F, and mean annual precipitation ranges from 35 to 40 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the well drained Dakota and poorly drained Mudhen(T) soils. Dakota soils are on summits of ridges upslope from Coot soils. Mudhen soils are in lower positions.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Surface runoff is slow. Permeability is moderate in upper three-fourths of the control section and rapid in the sandy lower one-fourth. Flooding from stream overflow is occasional during the spring. These soils have an apparent water table at a depth of 1.0 to 3.0 feet below the surface during the spring in most years.
USE AND VEGETATION: Most areas are cultivated. Corn, soybeans and small grains are the principal crops. The original vegetation is tall prairie grasses.
DISTRIBUTION AND EXTENT: Western Illinois; MLRA 115. They are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES PROPOSED: Fulton County, Illinois, 1995. Name coined from site location of Duck Island.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 15 inches (Ap and A horizons); argillic horizon - the zone from approximately 15 to 32 inches (Bt1, Bt2, 2Bt3, and 2Bt4 horizons); strongly contrasting particle size classes - the transition between gravelly clay loam and gravelly loamy coarse sand that occurs at approximately 32 inches; a paralithic contact at a depth of 41 inches; aquic conditions - chroma of 2 or less and redox concentrations in the Bt and 2Bt horizons.