LOCATION HURST IL+MOEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aeric Chromic Vertic Epiaqualfs
TYPICAL PEDON: Hurst silt loam - on a nearly level tread of a lacustrine terrace in a cultivated field at an elevation of about 385 feet above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; dark grayish brown (10YR4/2) silt loam, light brownish gray (10YR6/2) dry; weak medium granular structure; friable; many very fine roots; common fine and medium rounded black (7.5YR2.5/1) iron-manganese nodules with sharp boundaries; about 21 percent clay; slightly acid; abrupt smooth boundary. (5 to 9 inches thick)
E--7 to 12 inches; brown (10YR5/3) silt loam, very pale brown (10YR7/3) dry; moderate medium platy structure parting to weak fine subangular blocky; friable; common very fine roots; many fine faint light brownish gray (10YR6/2) iron depletions and common medium faint yellowish brown (10YR5/4) masses of iron accumulation in the matrix; common fine and medium rounded black (7.5YR2.5/1) iron-manganese nodules with sharp boundaries; about 22 percent clay; strongly acid; clear smooth boundary (0 to 8 inches thick)
Bt1--12 to 18 inches; yellowish brown (10YR5/4) silty clay loam; moderate fine and medium subangular blocky structure; firm; common very fine roots; common continuous distinct brown (10YR4/3) clay films on faces of peds; many continuous prominent very pale brown (10YR8/2) clay depletions on faces of peds; many fine and medium distinct light brownish gray (10YR6/2) iron depletions and common medium prominent strong brown (7.5YR5/6) masses of iron accumulation in the matrix; few fine rounded very dark brown (7.5YR2.5/2) iron-manganese nodules with clear strong brown (7.5YR4/6) boundaries; about 30 percent clay; very strongly acid; clear smooth boundary. (0 to 7 inches thick)
2Bt2--18 to 28 inches; brown (10YR5/3) silty clay; weak fine prismatic structure parting to weak medium angular blocky; very firm; common very fine roots; common continuous distinct dark grayish brown (10YR4/2) clay films on faces of peds; many fine faint grayish brown (10YR5/2) iron depletions and common fine prominent strong brown (7.5YR5/6) masses of iron accumulation in the matrix; common fine irregular strong brown (7.5YR4/6) masses of iron-manganese accumulation with clear boundaries; about 43 percent clay; very strongly acid; gradual smooth boundary.
2Btg1--28 to 40 inches; grayish brown (2.5Y5/2) silty clay loam; weak fine prismatic structure parting to weak medium angular blocky; very firm; few very fine roots; common continuous distinct dark grayish brown (10YR4/2) clay films on faces of peds and few continuous prominent brown (10YR4/3) clay films lining large channels; few fine and medium prominent strong brown (7.5YR5/6) masses of iron accumulation in the matrix; few fine irregular strong brown (7.5YR4/6) masses of iron-manganese accumulation with clear boundaries; about 38 percent clay; very strongly acid; clear smooth boundary.
2Btg2--40 to 53 inches; grayish brown (2.5Y5/2) silty clay; weak medium prismatic structure parting to weak medium angular blocky; very firm; few very fine roots; common continuous distinct dark grayish brown (10YR4/2) clay films on faces of peds; common continuous prominent black (N2.5/0) iron-manganese coatings on faces of peds and lining large channels; few fine prominent yellowish brown (10YR5/6) and common fine distinct dark brown (10YR3/3) masses of iron accumulation in the matrix; about 46 percent clay; moderately acid; clear smooth boundary.
2Btg3--53 to 62 inches; grayish brown (2.5Y5/2) silty clay loam; weak medium prismatic structure parting to weak coarse angular blocky; firm; few very fine roots; common continuous distinct dark grayish brown (10YR4/2) clay films on faces of peds; common medium prominent yellowish brown (10YR5/6) masses of iron accumulation in the matrix; many coarse irregular black (7.5YR2.5/1) masses of iron-manganese accumulation with clear strong brown (7.5YR5/6) boundaries; about 37 percent clay; slightly effervescent; slightly alkaline; clear smooth boundary. (Combined thickness of the 2Bt and 2Btg horizons is 36 to 60 inches.)
2BCkg--62 to 76 inches; olive gray (5Y4/2) silty clay; weak medium prismatic structure parting to moderate medium angular blocky; very firm; few very fine roots; common continuous distinct olive gray (5Y4/2) pressure faces on faces of peds; common continuous distinct very dark brown (7.5YR2.5/3) iron-manganese coatings on ped faces and lining large channels; few fine prominent yellowish brown (10YR5/4) masses of iron accumulation in the matrix; few fine irregular black (7.5YR2.5/1) and strong brown (7.5YR5/6) masses of iron accumulation with diffuse boundaries; common fine and medium irregular white (10YR8/1,dry) carbonate concretions; about 45 percent clay; strongly effervescent; slightly alkaline; clear smooth boundary. (0 to 16 inches thick)
2Cg--76 to 80 inches; grayish brown (2.5Y5/2) silty clay loam; massive; firm; few continuous distinct dark grayish brown (10YR4/2) clay films lining vertical channels; common medium prominent strong brown (7.5YR4/6) masses of iron accumulation along vertical channels; few fine prominent yellowish brown (10YR5/4) masses of iron accumulation in the matrix; common fine irregular very dark brown (7.5YR2.5/2) masses of iron-manganese accumulation with diffuse strong brown (7.5YR5/6) boundaries; about 33 percent clay; slightly alkaline.
TYPE LOCATION: Williamson County, Illinois; about 3 miles east of Hurst; approximately 1,490 feet north and 1,200 feet west of the southeast corner of sec. 10 , T. 8 S., R. 1 E.; USGS Herrin, IL. topographic quadrangle; lat. 37 degrees 50 minutes 15 seconds N. and long. 89 degrees 4 minutes 48 seconds W.
RANGE IN CHARACTERISTIC: Depth to the base of the argillic horizon is 44 to more than 80 inches. Depth to the clayey lacustrine sediments is 24 inches or less. The silty mantle is not present in some eroded pedons. In the lacustrine sediments some pedons have thin subhorizons or redoximorphic concentrations that have colors with hue redder than 10YR. The particle-size control section averages 35 to 55 percent clay and less than 15 percent sand. Some pedons have subhorizons that contain as much as 60 percent clay.
The upper part of the series control section (Ap or A, and E) has properties as follows: The Ap or A horizon has value of 4 or 5 (6 or 7 dry) and chroma of 2 or 3. Some pedons have an A horizon as much as 5 inches in thickness with color value of 3. Texture commonly is silt loam, but some pedons are silty clay loam. Clay content averages 20 to 27 percent, but ranges from 18 to 35 percent. Sand content is less than 15 percent. Reaction is strongly acid or moderately acid except pedons that have been limed range to neutral, and some eroded pedons range to very strongly acid because of the mixing of subsoil material. The E horizon, where present, has value of 5 or 6 (6 to 8 dry) and chroma of 2 or 3. The E horizon commonly is silt loam, but in pedons that have little or no loess cover, texture is silty clay loam. Clay content averages 18 to 30 percent and sand content is less than 15 percent. Reaction is extremely acid to moderately acid, except pedons that have been limed range to slightly acid. Some pedons that are eroded or cultivated deeply do not have an E horizon.
Some pedons, especially those having a loess mantle nearly 24 inches in thickness, have a thin silt loam or silty clay loam BE or Bt horizon that formed in the upper silty material.
The next part of the series control section (2Bt and 2Btg) have properties as follows: The 2Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 3 or 4. Texture is silty clay loam, silty clay, or clay. Reaction is extremely acid to moderately acid. The 2Btg horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 or 2. Texture is silty clay loam, silty clay, or clay. Reaction is extremely acid to neutral, and ranges to slightly alkaline in the lower part of some pedons. Some pedons contain secondary carbonates in the lower part.
Some pedons have a 2BC horizon.
The lower part of the series control section (2C) has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 to 4. The 2C horizon typically is silty clay loam or silty clay. Clay content ranges from 27 to 45 percent and sand content is less than 20 percent. A sandy substratum phase is recognized that is loamy sand or sand in the C horizon. Reaction is very strongly acid to moderately alkaline. Carbonates are common, but are not everywhere present.
COMPETING SERIES: These are the Ashgrove, Atlas, Bluford, and Kernan series. Ashgrove and Kernan soils have a mean annual soil temperature less than 56 degrees F. Atlas soils have a gravel content that ranges from a few pebbles to 5 percent. Bluford soils have a 2Btx horizon.
GEOGRAPHIC SETTING: Hurst soils are on nearly level or gently sloping treads and sloping risers of lacustrine terraces and lake plains; mainly along major tributaries of the Mississippi River. Some areas are subject to flooding during rare or occasional high flood events. Slope ranges from 0 to 15 percent. Hurst soils formed in the dominantly clayey lacustrine sediments and have a mantle of loess or other silty material less than 24 inches in thickness. The lacustrine sediments in and underlying the Hurst series are weathered to depths of 10 or 12 feet. Below 80 inches the stratified lacustrine sediments have coarse structure and widely-spaced cleavage planes, slickensides and pressure faces, clay films on faces of structural units and in channels, segregation of iron-manganese oxides, accumulation of secondary carbonates, and the presence of dark strata. Mean annual air temperature is 54 to 57 degrees F., mean annual soil temperature is 56 to 59 degrees F., mean annual precipitation is 36 to 44 inches, frost-free period is 180 to 210 days, and the elevation is 340 to 450 feet above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Colp, Geff, Okaw, Ridgway, Redbud, and Wagner series. The moderately well drained Colp soils are on more sloping parts of the same landform. The somewhat poorly drained Geff and well drained Ridgway soils contain less clay and more sand in the control section and are on stream terraces nearby. The poorly drained Okaw and Wagner soils are on nearly level or slightly depressional treads of the same landform. The Okaw and Colp soils form a hydrosequence with Hurst soils. The moderately well drained Redbud soils occur on loess-covered lacustrine terraces nearby.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained and very slow permeability. The potential for surface water runoff is low or medium. In drained areas, depth to an intermittent perched 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 wheat. Some areas are pastured or wooded. Native vegetation is mixed hardwood forest.
DISTRIBUTION AND EXTENT: Southern Illinois and Missouri; extent is moderate, and mainly in MLRA(s) 113, 114, and 115.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Williamson County, Illinois, 1952.
REMARKS: Diagnostic horizons and features in this pedon include: Ochric epipedon - from the surface of the soil to a depth of 12 inches (Ap and E horizons). Albic horizon - from a depth of 7 to 12 inches (E horizon). Argillic horizon - from a depth of approximately 12 to 62 inches (Bt1, 2Bt2, 2Btg1, 2Btg2, and 2Btg3 horizons). Aquic conditions - periodic episaturation and reduction, indicated by redoximorphic features throughout the soil.
The typical pedon was moved to a new location in the same map unit with this revision.