LOCATION MYRTLE IL+WIEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Myrtle silt loam at an elevation of 320 meters (1050 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 20 centimeters (0 to 8 inches); very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; moderate fine granular structure; friable; neutral (pH 6.9); abrupt smooth boundary. [15 to 23 cm (6 to 9 inches) thick]
E--20 to 36 centimeters (8 to 14 inches); dark grayish brown (10YR 4/2) silt loam; weak medium platy structure parting to weak fine and medium granular; friable; slightly acid (pH 6.3); clear smooth boundary. [10 to 20 cm (4 to 8 inches) thick]
Bt1--36 to 48 centimeters (14 to 19 inches); brown (10YR 4/3) silty clay loam; moderate very fine subangular blocky structure; friable; few faint very dark grayish brown (10YR 3/2) organo-clay films on horizontal faces of peds; common distinct light gray (10YR 7/1) dry, silt coatings on faces of peds; moderately acid (pH 5.8); clear smooth boundary.
Bt2--48 to 69 centimeters (19 to 27 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate fine subangular blocky structure; firm; common distinct dark brown (10YR 3/3) clay films on faces of peds; common light gray (10YR 7/1) dry, silt coatings on faces of peds; moderately acid (pH 5.8); clear smooth boundary.
Bt3--69 to 94 centimeters (27 to 37 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; firm; common distinct dark brown (10YR 3/3) and very dark grayish brown (10YR 3/2) clay films on faces of peds; common light gray (10YR 7/1) dry, silt coatings on faces of peds; moderately acid (pH 5.8); gradual smooth boundary.
Bt4--94 to 107 centimeters (37 to 42 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; firm; common distinct dark brown (7.5YR 3/3) clay films on faces of peds; few distinct light gray (10YR 7/1) dry, silt coatings on faces of a few peds; about 12 percent by volume sand; moderately acid (pH 5.8); clear smooth boundary. (Combined thickness of the Bt horizon is 43 to 69 cm, 20 to 36 inches) 17 to 27 inches)]
2Bt5--107 to 203 centimeters (42 to 80 inches); brown (7.5YR 4/4) clay loam; moderate medium and coarse subangular blocky structure; firm; common distinct reddish brown (5YR 4/4) and dark reddish brown (5YR 3/3) clay films on faces of peds; few fine prominent black (N 2.5/) iron and manganese oxide stains in the matrix; moderately acid (pH 5.8).
TYPE LOCATION: Stephenson County, Illinois; about 490 feet west and 165 feet north of the southeast corner, sec. 19, T. 29 N., R. 9 E. USGS Davis quadrangle; lat. 42 degrees, 29 minutes, 27 seconds N and long. 89 degrees, 29 minutes, 58 seconds W; NAD 83.
RANGE IN CHARACTERISTICS: The solum thickness is greater than 152 centimeters (60 inches). The loess typically is 76 to 127 centimeters (30 to 50 inches) thick. The paleosollic 2Bt horizon in drift extends to dolomitic bedrock at depths of about 216 to 229 centimeters (85 to 90 inches) in many pedons. The solum ranges from moderately acid to very strongly acid except for Ap horizons that have been limed.
The A or Ap horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is silt loam.
The E horizon has hue of 10YR, value of 4 or 5, and chroma of 2 or 3. It is silt loam.
The Bt horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 3 to 5. It is dominantly silty clay loam, but is silt loam in the upper part in some pedons. The content of fine and coarser sand commonly is less than 5 percent but ranges to 15 percent by volume just above the 2Bt horizon in some pedons. Structure commonly is moderate or strong, fine to coarse, subangular or angular blocky.
The 2Bt horizon has hue of 7.5YR, 5YR, or 2.5YR, value and chroma of 4 to 6. Hue of 5YR or redder is present on faces of peds or in the matrix in at least one subhorizon. It is silty clay loam with moderate content of sand, clay loam or sandy clay loam. The clay content decreases by more than 20 percent of the maximum within a depth of 152 centimeters (60 inches) below the soil surface in most pedons, especially in those that have chroma greater than 4. Rock fragment content ranges from 1 to 5 percent. Many of the properties of the 2Bt horizon are believed to have been inherited from the paleosol of late Sangamon age.
The 2C horizon, where described, has dominant hue of 10YR or 7.5YR, value and chroma of 4 to 6. It is loam, clay loam, or sandy loam. Reaction is neutral or mildly alkaline and, in some pedons, contains free carbonates.
COMPETING SERIES: These are the Batavia, Bowes, Churchtown, Derion, Downs, Ella, Festina, Frankville, Gladek, Greenbush, Harvard, Hersey, Knox, Luana, Mannon, Massbach, Mellott, Mt. Carroll, Nasset, Newhouse, Watkins, Waubeek, and Yutan soils. Ashton soils have sola less than 60 inches thick and the lower part formed in loamy alluvium. Batavia, Bowes, Churchtown, Downs, Festina, Gladek, Greenbush, Harvard, Hersey, Knox, Luana, Mannon, Mellott, Mt. Carroll, Watkins, Waubeek, and Yutan soils are not as red as 5YR in the matrix or on faces of peds in any part of the series control section. Derion soils are less acid than medium acid in the upper part of the argillic horizon. Frankville, Massbach and Nasset soils have a lithic or paralithic contact within a depth of 152 cm (60 inches). Newhouse soils average less than 27 percent clay in the particle size control section. Shelbyville soils have silty clay or clay 2B horizons.
GEOGRAPHIC SETTING: Myrtle soils are on undulating to steep glacial till plains and moraines. Slope gradient ranges from 2 to 20 percent. These soils formed in 76 to 127 cm (30 to 50 inches) of loess and late Sangamon reddish paleosols that formed in sandy loam, loam or clay loam Illinoian glacial till. These soils have continental climate with hot summers and cold winters. Mean annual temperature is between 7 and 14 degrees C (45 and 57 degrees F), and mean annual precipitation is between 710 and 970 mm (28 and 38 inches).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Argyle, Flagg, Ogle, Pecatonica and Westville soils. Myrtle soils are the intergrade member of a biosequence with the well drained Flagg (Alfisol) and Ogle (Mollisol) soils on similar landscapes. Argyle, Pecatonica, and Westville soils have thinner loess mantles and are on similar positions nearby. In addition, the Pecatonica and Westville soils have surface layers less than 15 cm (6 inches) thick that have moist color value of 3 or less.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. medium or high runoff. Saturated hydraulic conductivity is 4.23 to 14.11 micrometers per second (moderate permeability).
USE AND VEGETATION: The Myrtle soils are used mostly for cultivated crops such as corn, small grain, and meadow crops. Some areas are used for pasture. Native vegetation is probably mixed prairie grass and hardwood trees.
DISTRIBUTION AND EXTENT: Major land resource area (MLRA) 95B and 108. Northwestern Illinois and southwest Wisconsin. Known extent is small.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Stephenson County, Illinois, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
chric epipedon -- the zone from the surface to a depth of 36 cm (14 inches) (Ap and E horizons).
Albic horizon -- the zone from 20 to 36 cm (8 to 14 inches) (E horizon).
Argillic horizon -- the zone from 36 to 203 cm (14 to 80 inches) (Bt1, Bt2, Bt3, Bt4, and 2Bt5 horizons).