LOCATION BETHALTO ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Udollic Endoaqualfs
TYPICAL PEDON: Bethalto silt loam - with an east-facing slope with a 2 percent gradient in a cultivated field at an elevation of about 500 feet above sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; friable; common very fine roots; common fine tubular pores; few fine rounded black (10YR 2/1) and strong brown (7.5YR 5/6) iron-manganese nodules with sharp boundaries; about 21 percent clay; neutral; abrupt smooth boundary. (6 to 9 inches thick)
Eg1--8 to 11 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; moderate medium platy structure parting to weak fine granular; friable; few very fine roots; few fine tubular pores; common distinct gray (10YR 6/1,dry) clay depletions along pores; few fine faint brown (10YR 4/3) masses of iron accumulations in the matrix; few fine rounded black (10YR 2/1) and strong brown (7.5YR 5/6) iron-manganese nodules with sharp boundaries; about 19 percent clay; neutral; clear smooth boundary.
Eg2--11 to 15 inches; grayish brown (10YR 5/2) silt loam, light brownish gray (10YR 6/2) dry; weak thick platy structure parting to weak medium granular; friable; few very fine roots; few fine tubular pores; many distinct light gray (10YR 7/1,dry) clay depletions on faces of peds and along pores; few fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulaton in the matrix; common fine rounded black (10YR 2/1) and strong brown (7.5YR 5/6) iron-manganese nodules with sharp boundaries; about 18 percent clay; slightly acid; clear smooth boundary. (Combined thickness of the E horizon is 5 to 10 inches.)
Bt--15 to 24 inches; brown (10YR 4/3) silty clay loam; moderate fine prismatic structure parting to moderate fine and medium subangular blocky; firm; few very fine roots; few fine tubular pores; few distinct light gray (10YR 7/1,dry) clay depletions on faces of peds and along pores; many distinct dark grayish brown (10YR 4/2) clay films on faces of peds; common fine faint light brownish gray (10YR 6/2) iron depletions and few fine faint dark yellowish brown (10YR 4/4) masses of iron accumulation in the matrix; few fine and medium rounded black (7.5YR 2.5/1) iron-manganese nodules with clear boundaries; about 32 percent clay; moderately acid; clear smooth boundary.
Btg1--24 to 36 inches; grayish brown (10YR 5/2) silty clay loam; weak fine prismatic structure parting to moderate fine and medium subangular blocky; firm; few very fine roots; few very fine tubular pores; many distinct dark grayish brown (10YR 4/2) clay films on faces of peds; many medium prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; common fine rounded black (7.5YR 2.5/1) iron-manganese nodules with clear boundaries; about 31 percent clay; moderately acid; gradual smooth boundary.
Btg2--36 to 48 inches; grayish brown (10YR 5/2) silty clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; firm; few very fine roots; few very fine tubular pores; many distinct dark grayish brown (10YR 4/2) clay films on faces of peds and lining pores; many medium and coarse prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; common fine and medium irregular very dark brown (7.5YR 2.5/2) and strong brown (7.5YR 4/6) iron-manganese nodules with clear boundaries; about 30 percent clay; slightly acid; gradual smooth boundary.
Btg3--48 to 62 inches; grayish brown (10YR 5/2) silty clay loam; weak medium prismatic structure parting to weak medium subangular blocky; friable; few very fine roots; few very fine tubular pores; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds and lining pores; many medium and coarse prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; common fine and medium irregular very dark brown (7.5YR 2.5/2) and strong brown (7.5YR 4/6) iron-manganese nodules with clear boundaries; about 28 percent clay; slightly acid; clear smooth boundary. (Combined thickness of the Bt and Btg horizons is 31 to 51 inches.)
BCtg--62 to 70 inches; light brownish gray (10YR 6/2) silt loam; weak coarse angular blocky structure; friable; few fine vesicular pores; common distinct dark grayish brown (10YR 4/2) clay films on vertical faces of peds; few prominent very dark grayish brown (10YR 3/2) organo-clay films lining root channels and filling pores; common medium and coarse prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; common fine and medium irregular very dark brown (7.5YR 2.5/2) iron-manganese nodules with clear strong brown (7.5YR 5/6) boundaries; about 26 percent clay; slightly acid; gradual smooth boundary. (0 to 10 inches thick)
Cg--70 to 80 inches; light brownish gray (2.5Y 6/2) silt loam; massive; friable; few fine vesicular pores; few distinct dark grayish brown (10YR 4/2) clay films lining root channels and filling pores; common medium prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few medium irregular strong brown (7.5YR 5/6) masses of iron-manganese oxides; about 23 percent clay; neutral.
TYPE LOCATION: Madison County, Illinois; about 2.5 miles northeast of Troy; approximately 1,060 feet north and 500 feet west of the center of sec. 35, T. 4 N., R. 7 W.; USGS MARINE, ILL. topographic quadrangle; lat. 38 degrees 45 minutes 15 seconds N. and long. 89 degrees 50 minutes 50 seconds W.
RANGE IN CHARACTERISTICS: Depth to the base of soil development is 42 to 80 inches. Depth to carbonates, where present, is greater than about 5 feet. The particle-size control section averages 27 to 35 percent clay and contains less than 7 percent sand. Sand content of the A and E horizons is less than 10 percent and includes iron-manganese nodules and concretions. The mean annual soil temperature ranges from 56 to slightly less than 59 degrees F.
The upper part of the control section has properties as follows: The Ap or A horizon has value of 2 or 3 (4 or 5 dry) and chroma of 1 or 2. Clay content is 18 to 27 percent. Reaction is moderately acid to neutral depending upon liming practices.
The Eg or E horizon has value of 4 to 6 (6 or 7 dry) and chroma of 1 to 3. Clay content is 15 to 25 percent. Reaction is strongly acid to neutral.
Some pedons have an EB or BE horizon. It is silt loam or silty clay loam.
The middle part of the control section (B and BC) has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 2 to 4. Redoximorphic iron depletions and concentrations have hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 7; and chroma of 1 to 8. It is silty clay loam in the upper part and is silty clay loam or silt loam in the lower part. Clay content is 27 to 35 percent in the upper part and is 20 to 30 percent in the lower part. Reaction is strongly acid to neutral, and ranges to slightly alkaline in the lower part.
The lower part of the control section (C) has hue of 10YR, 2.5Y, or 5Y; value of 5 or 6; and chroma 1 to 4. Redoximorphic iron depletions and concentrations commonly have hue of 7.5YR, 10YR, or 2.5Y; value of 5 to 7; and chroma of 1 to 8. Clay content is 18 to 27 percent and sand content is less than 7 percent. Reaction is moderately acid to moderately alkaline.
COMPETING SERIES: These are the Atterberry, Emery (T), Millbrook, Mulvey, Virgil, and Wauconda series.
Atterberry soils have a mean annual soil temperature of less than 56 degrees F. Emery, Millbrook, Mulvey, Virgil, and Wauconda soils contain more than 7 percent sand in the lower part of the series control section.
GEOGRAPHIC SETTING: Bethalto soils are on nearly level or gently sloping summits on till plains. They are in areas of transition between prairie grass and deciduous forest. Slope gradients typically are between 1 and 3 percent and range from 0 to 5 percent. These soils formed in loess. Mean annual temperature is 54 to 57 degrees F., mean annual precipitation is 36 to 40 inches, frost-free period is 170 to 200 days, and elevation is 400 to 800 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caseyville, Downsouth, Edwardsville, Mascoutah, Menfro, Wakenda, and Winfield soils. The somewhat poorly drained Caseyville soils, the moderately well drained Winfield soils, and the well drained Menfro soils formed under deciduous forest in areas closer to the drainageways. The moderately well drained Downsouth soils form a hydrosequence with the Bethalto soils. The somewhat poorly drained Edwardsville soils have a mollic epipedon and are in similar landform positions farther from the drainageways. The poorly drained Mascoutah soils are on lower parts of the landform nearby and they have a mollic epipedon. The Bethalto soils form a biosequence with the Caseyville and Edwardsville soils. The well drained Wakenda soils have a mollic epipedon and are on more sloping summits farther from the drainageways.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Permeability is moderate. Surface runoff is slow or medium. In drained areas, depth to an intermittent apparent high water table is 0.5 foot to 2.0 feet from December to April in most years.
USE AND VEGETATION: Most areas are cropped to corn, soybeans, and small grain. Native vegetation is mixed prairie grasses and deciduous forest.
DISTRIBUTION AND EXTENT: Southwestern Illinois. Extent is moderate, and mainly in MLRA 115.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Madison County, Illinois, 1997. The Bethalto series was named for a town in Madison County.
REMARKS: Bethalto soils were formerly included with the Atterberry series.
Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - the zone from the surface to a depth of 15 inches (Ap, Eg1, and Eg2 horizons). Albic horizon - the zone from 8 to 15 inches (Eg1 and Eg2 horizons). Argillic horizon - the zone from approximately 15 to 62 inches (Bt, Btg1, Btg2, and Btg3 horizons). Aquic conditions - periodic saturation and reduction indicated by redoximorphic features throughout the soil.