LOCATION DOWNS IA+IL MN WIEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Downs silt loam, on a gently sloping ridgetop, in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 20 centimeters; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; friable; slightly acid; abrupt smooth boundary. (12 to 24 centimeters thick)
E--20 to 30 centimeters; dark grayish brown (10YR 4/2) silt loam; faces of peds very dark grayish brown (10YR 3/2); some mixing of brown (10YR 4/3); weak medium platy structure parting to weak fine granular; friable; few distinct gray (10YR 6/1) dry, silt coats on primary peds; moderately acid; clear smooth boundary. (0 to 16 centimeters thick)
BE--30 to 43 centimeters; brown (10YR 4/3) silt loam; faces of peds dark brown (10YR 3/3); moderate fine and very fine subangular blocky structure; friable; common distinct gray (10YR 6/1) dry, silt coats; strongly acid; gradual smooth boundary. (8 to 16 centimeters thick)
Bt1--43 to 61 centimeters; dark yellowish brown (10YR 4/4) silty clay loam; faces of peds brown (10YR 4/3); moderate fine subangular blocky structure; friable; few distinct dark brown (10YR 3/3) clay films; common distinct light gray (10YR 7/1) dry, silt coats; strongly acid; gradual smooth boundary.
Bt2--61 to 84 centimeters; yellowish brown (10YR 5/4) silty clay loam; faces of peds brown (10YR 4/3); weak medium subangular blocky structure; friable; few distinct dark yellowish brown (10YR 3/4) clay films; common distinct light gray (10YR 7/1) dry, silt coats; strongly acid; gradual smooth boundary.
Bt3--84 to 99 centimeters; yellowish brown (10YR 5/4) silt loam; faces of peds brown (10YR 5/3); weak coarse prismatic structure parting to weak fine and medium subangular blocky; friable; few distinct dark yellowish brown (10YR 3/4) clay films; common distinct light gray (10YR 7/1) dry, silt coats; strongly acid; gradual smooth boundary. (Combined thickness of Bt horizon is 45 to 100 centimeters.)
BC1--99 to 122 centimeters; yellowish brown (10YR 5/4) silt loam; faces of peds brown (10YR 5/3); weak coarse prismatic structure parting to weak coarse subangular blocky; friable; common distinct light gray (10YR 7/1) dry, silt coats mainly on prisms; few fine dark reddish brown (5YR 3/2) accumulations; moderately acid; gradual smooth boundary. (14 to 46 centimeters thick)
BC2--122 to 152 centimeters; pale brown (10YR 6/3) silt loam; yellowish brown (10YR 5/4) rubbed; weak coarse prismatic structure; friable; common distinct light gray (10YR 7/1) dry, silt coats of prisms; few fine dark reddish brown (5YR 3/2) accumulations; common medium prominent strong brown (7.5YR 5/6) redoximorphic concentrations; few medium faint grayish brown (10YR 5/2) redoximorphic depletions; moderately acid.
TYPE LOCATION: Major Land Resource Area (MLRA) 105-Northern Mississippi Valley Loess Hills, Clayton County, Iowa subset; 6 miles north of Garnavillo on Highway 52 to National and 1 mile east and 1/4 mile north; located about 1,100 feet north and 50 feet east of the southwest corner of section 13, T. 94 N., R. 4 W.; USGS Farmersburg topographic quadrangle; lat. 42 degrees 57 minutes 11.8 seconds N. and long. 91 degrees 16 minutes 13.0 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Depth to carbonates--greater than 150 centimeters
Clay content in the particle-size control section (weighted average)--24 to 32 percent
Sand content in the particle-size control section (weighted average)--less than 10 percent
Rock fragment content--0 percent
A or Ap horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silt loam
Clay content--18 to 26 percent
Sand content--less than 10 percent
Reaction--moderately acid to neutral
E horizon (when present):
Hue--10YR
Value--3 to 5
Chroma--2 or 3
Texture--silt loam
Clay content--18 to 26 percent
Sand content--less than 10 percent
Reaction--strongly acid to neutral
BE horizon:
Hue--10YR
Value--4
Chroma--3 or 4
Texture--silt loam
Clay content--18 to 26 percent
Sand content--less than 10 percent
Reaction--very strongly acid to slightly acid
Bt horizon:
Hue--10YR
Value--4 or 5
Chroma--3 to 6
Texture--silty clay loam or silt loam
Clay content--24 to 32 percent
Sand content--less than 10 percent
Reaction--very strongly acid to slightly acid
Some pedons have subhorizons that have a clay content of up to 35 percent
BC and C (when present) horizons:
Hue--10YR
Value--5 or 6
Chroma--3 to 6
Texture--silt loam or silty clay loam
Clay content--20 to 30 percent
Sand content--less than 10 percent
Reaction--strongly acid to slightly acid
2C horizon, below 150 centimeters (if present):
Hue--10YR
Value--5 or 6
Chroma--3 to 6
Texture--loamy fine sand, loamy sand, or fine sand
Clay content--3 to 10 percent
Sand content--75 to 90 percent
Reaction--strongly acid to neutral
COMPETING SERIES: These are the
Batavia,
Bowes,
Churchtown,
Deroin,
Ella,
Festina,
Frankville,
Gladek,
Greenbush,
Harvard,
Hersey,
Knox,
Luana,
Mannon,
Massbach,
Mellott,
Mt. Carroll,
Myrtle,
Nasset,
Newhouse,
Oak Center,
Watkins,
Waubeek, and
Yutan series.
Batavia--have more than 10 percent sand in the lower third of the series control section
Bowes--have more than 30 percent sand and have a rock fragment content of more than 15 percent in the lower third of the series control section
Churchtown--have 10 to 55 percent sand in the upper half of the series control section
Deroin--have a matrix hue of 5YR or 7.5YR in the lower two thirds of the series control section
Ella--have an average of 15 to 60 percent fine sand or sand coarser than fine sand in the lower third of the series control section
Festina--have a clay content that averages 24 to 29 percent in the particle-size control section and average more than 10 percent sand throughout the series control section
Frankville--have a lithic contact with limestone within a depth of 100 centimeters
Gladek--have carbonates within a depth of 150 centimeters
Greenbush--have a frequently saturated zone at a depth of 1.2 meters centimeters during the wettest periods of normal years
Harvard--have more than 15 percent sand in the lower one third of the series control section
Hersey--have a rock fragment content of 2 to 15 percent and average more than 15 percent fine sand and sand coarser than fine sand in the lower third of the series control section
Knox--are in areas that have mean annual air temperature range of 12 to 14 degrees C
Luana--have a rock fragment content of 10 to 35 percent in the lower third of the series control section
Mannon--have a clay content that averages 18 to 27 percent in the particle-size control section and have a frequently saturated zone at a depth of 1.2 meters during the wettest periods of normal years
Massbach--have a paralithic contact with calcareous silty clay or clay shale within a depth of 150 centimeters
Mellott--have carbonates within a depth of 150 centimeters and have a sand content of 35 to 65 percent in the lower third of the series control section
Mt. Carroll--have a clay content that averages 18 to 24 percent in the particle-size control section
Myrtle--have a matrix hue of 2.5YR, 5YR or 7.5YR in the lower third of the series control section
Nassett--have a lithic contact with limestone within a depth of 150 centimeters
Newhouse--have a clay content that averages 18 to 27 percent in the particle-size control section and have 5 to 35 percent chert and sandstone fragments in the lower third of the series control section
Oak Center--have a sand content of more than 35 percent within a depth of 150 centimeters
Watkins--have a clay content that averages 30 to 35 percent in the particle-size control section and have a clay content of 27 to 32 percent in the lower third of the series control section
Waubeek--have a sand content of 35 to 65 percent in the lower third of the series control section
Yutan--have a clay content of 35 to 40 percent in the ochric epipedon
GEOGRAPHIC SETTING:
Parent material--loess
Landform--interfluves and side slopes on uplands and on treads and risers on stream terraces
Slope--0 to 35 percent
Elevation--100 to 460 meters above sea level
Mean annual air temperature--6 to 13 degrees C
Mean annual precipitation--585 to 1,015 millimeters
Frost-free period--145 to 225 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Dubuque,
Fayette,
Franklin, and
Tama soils.
Dubuque--are at lower landscape positions, have ochric epipedons 5 to 10 centimeters thick, and have a lithic contact with limestone within a depth of 100 centimeters
Fayette--are in landscape positions similar to those of the Downs soils and have surface layers 2 to 10 centimeters thick
Franklin--are at lower landscape positions, have ochric epipedons 15 to 23 centimeters thick, and have a lithic contact with limestone within a depth of 100 centimeters
Tama--are in landscape positions similar to those of the Downs soils and have mollic epipedons 25 to 50 centimeters thick
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained--frequent saturation does not occur within a depth of 1.8 meters during the wettest periods of normal years
Saturated hydraulic conductivity--1.00 to 10.00 micrometers per second
Surface runoff potential--negligible to high
USE AND VEGETATION:
Nearly level to gently sloping areas are cultivated. The principal crops are corn, soybeans, small grains, and legume hays. Steeper slopes are pastured, wooded or both wooded and pastured. The native vegetation is big bluestem, little bluestem, switchgrass, other grasses of the tall grass prairie and widely spaced oak and hickory trees.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic sections--Eastern lake section, Wisconsin driftless section, Dissected till plains, Till plains
MLRAs--Southern Wisconsin and Northern Illinois Drift Plain (95B),
Eastern Iowa and Minnesota Till Prairies (104),
Northern Mississippi Valley Loess Hills (105),
Illinois and Iowa Deep Loess and Drift (108),
Iowa and Missouri Heavy Till Plain (109), and
Central Mississippi Valley Wooded Slopes (115)
LRR M and LRR L; eastern Iowa, southern Minnesota, southwestern Wisconsin, and northwestern Illinois
Extent--large
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Freeport Project (SCS), Stephenson County, Illinois, 1969.
REMARKS:
Particle-size control section--the zone from a depth of 43 to 93 centimeters (Bt1, Bt2, and Bt3 horizons);
series control section--the zone from the surface to a depth of 150 centimeters (Ap, E, BE, Bt1, Bt2, Bt3, BC, and C horizons).
Diagnostic horizons and features recognized in this pedon include:
ochric epipedon--the zone from the surface to a depth of 43 centimeters (Ap, E and BE horizons);
albic horizon--the zone from a depth of 20 to 30 centimeters (E horizon);
argillic horizon-the zone from a depth of 43 to 99 centimeters (Bt1, Bt2, and Bt3 horizons);
udic moisture regime.
Cation-exchange activity class is supported by lab data from National Soil Survey Laboratory, Lincoln, Nebraska.
Clay content in the particle-size control section and lower third of the series control section is based on analysis of laboratory data (NSSL).
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.
ADDITIONAL DATA:
Laboratory data--National Soil Survey Laboratory, Lincoln, Nebraska many pedons (http://ssldata.sc.egov.usda.gov/).