LOCATION EXETTE IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Dystric Eutrudepts
TYPICAL PEDON: Exette silt loam, on a north-facing, convex 11 percent slope, in a cultivated field. (Colors are for moist soil unless other wise stated.)
Ap--0 to 15 centimeters (0 to 6 inches); dark grayish brown (10YR 4/2) with some brown (10YR 4/3) mixings silt loam, light brownish gray (10YR 6/2) dry; weak fine granular structure; friable; neutral; abrupt smooth boundary. [13 to 20 centimeters (5 to 8 inches) thick]
BA--15 to 28 centimeters (6 to 11 inches); brown (10YR 4/3) silt loam; weak fine and very fine subangular blocky structure; friable; few dark grayish brown (10YR 4/2) coatings on faces of peds; slightly acid; clear smooth boundary. [13 to 25 centimeters (5 to 10 inches) thick]
Bw1--28 to 71 centimeters (11 to 24 inches); dark yellowish brown (10YR 4/4) silt loam; weak and moderate medium subangular and angular blocky structure; friable; brown (10YR 4/3) coatings on faces of peds; common prominent light gray (10YR 7/2) dry silt coatings on faces of peds; few fine distinct grayish brown (10YR 5/2) relict redoximorphic depletions; moderately acid; clear smooth boundary.
Bw2--71 to 84 centimeters (24 to 33 inches); dark yellowish brown (10YR 4/4) silt loam; weak medium subangular blocky structure; friable; common distinct light gray (10YR 7/2) dry silt coatings on faces of peds; common fine distinct strong brown (7.5YR 5/6) relict redoximorphic concentrations and common fine distinct grayish brown (10YR 5/2) redoximorphic depletions; slightly acid; clear smooth boundary. [Combined thickness of the Bw horizon is 30 to 64 centimeters (12 to 25 inches).]
BC--84 to 104 centimeters (33 to 41 inches); mottled grayish brown (2.5Y 5/2) and yellowish brown (10YR 5/6) silt loam; weak medium prismatic structure; friable; few fine prominent yellowish red (5YR 4/6) relict redoximorphic concentrations; neutral; clear smooth boundary. [20 to 30 centimeters (8 to 12 inches) thick]
C1--104 to 137 centimeters (41 to 54 inches); grayish brown (2.5Y 5/2) silt loam; massive; friable; few fine prominent yellowish brown (10YR 5/6) and yellowish red (5YR 5/6) relict redoximorphic concentrations; neutral; abrupt wavy boundary. [30 to 61 centimeters (12 to 24 inches) thick]
C2--137 to 152 centimeters (54 to 60 inches); light brownish gray (2.5Y 6/2) silt loam; massive; friable; coarse yellowish red (5YR 4/6) iron segregations; common fine distinct light olive brown (2.5Y 5/4) relict redoximorphic concentrations; slightly alkaline; slightly effervescent.
TYPE LOCATION: Major Land Resource Area (MLRA) 105; Fayette County, Iowa; about 3 miles north and 5 miles east of Fayette; about 262 meters (860 feet) south and 24 meters (79 feet) west of the northeast corner of section 7, T. 93 N., R. 7 W.; USGS Elgin quadrangle; lat. 42 degrees 53 minutes 15.7 seconds N. and long. 91 degrees 42 minutes 24.1 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Depth to carbonates--greater than 102 centimeters (40 inches)
Content of clay in the particle-size control section (weighted average)--20 to 27 percent
Content of sand in the particle-size control section (weighted average)--less than 10 percent, typically less than 5 percent
A horizon:
Hue--10YR
Value--3
Chroma--1 or 2
Texture--silt loam
Clay content--18 to 26 percent
Reaction--moderately acid to neutral
Ap horizon (if it occurs):
Hue--10YR
Value--4
Chroma--2 or 3
Texture--silt loam
Clay content--18 to 26 percent
Reaction--moderately acid to neutral
E horizon (if it occurs):
Hue--10YR
Value--4 or 5
Chroma--2
Texture--silt loam
Clay content--18 to 25 percent
Reaction--moderately acid to neutral
Bw horizon:
Hue--10YR or 2.5Y
Value--4 to 6
Chroma--1 to 4
Texture--silt loam
Clay content--18 to 27 percent
Special features--redoximorphic features, present above a depth of 76 centimeters (30 inches), are considered relict
Reaction--moderately acid to neutral
BC horizon:
Hue--10YR or 2.5Y
Value--4 to 6
Chroma--1 to 8
Texture--silt loam
Clay content--15 to 20 percent
Reaction--moderately acid to neutral
Special features--matrix colors and redoximorphic features are considered relict
C horizon:
Hue--10YR or 2.5Y
Value--4 to 6
Chroma--1 to 8
Texture--silt loam
Clay content--15 to 20 percent
Reaction--moderately acid to slightly alkaline
Special features--matrix colors and redoximorphic features are considered relict
COMPETING SERIES: These are the
Contrary,
Drury, and
Killduff series.
Contrary--are in areas that have a mean annual air temperature range of 10 to 12 degrees C (50 to 54 degrees F)
Drury--have matrix hues of 7.5YR or 10YR in the cambic horizon and do not have redoximorphic features within a depth of 76 centimeters (30 inches)
Killduff--have a clay content of 27 and 33 percent in the particle-size control section
GEOGRAPHIC SETTING:
Parent material--loess
Landform--short, convex to linear side slopes and head slopes on uplands
Slopes--5 to 25 percent
Elevation--305 to 427 meters (1000 to 1400 feet) above sea level
Mean annual air temperature--7 to 10 degrees C (45 to 50 degrees F)
Mean annual precipitation--81 to 86 centimeters (32 to 34 inches)
Frost-free period--145 to 180 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Chaseburg,
Downs,
Dubuque, and
Fayette soils.
Chaseburg--are at lower elevations on base slopes, have a clay content of 10 to 18 percent in the particle-size control section, and have stratified layers in the lower two thirds of the series control section
Downs--are at higher elevations on side slopes and interfluves, have a clay content of 25 to 35 percent in the particle-size control section, and have surface layers 15 to 23 centimeters (6 to 9 inches) thick
Dubuque--are at higher elevations on side slopes and interfluves and have a lithic contact of dolomitic limestone within depths of 51 to 102 centimeters (20 to 40 inches)
Fayette--are at higher elevations on side slopes and interfluves, have a clay content of 27 to 35 percent in the particle-size control section, and have surface layers 2 to 10 centimeters (1 to 4 inches) thick
DRAINAGE AND PERMEABILITY:
Drainage class--well drained--saturation does not occur within a depth of 1.8 meters (6 feet) during the wettest periods of normal years
Saturated hydraulic conductivity--moderately high
Surface runoff potential--medium or high
USE AND VEGETATION:
The more gently sloping areas are cultivated. The principal crops are corn in a rotation with oats and legume hay. The more steeply sloping areas are pastured. The native vegetation is deciduous trees.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic section(s)--Dissected till plains, Wisconsin driftless section
MLRA(s)--Eastern Iowa and Minnesota Till Prairies (104), Northern Mississippi Valley Loess Hills (105), and Illinois and Iowa Deep Loess and Drift (108)
LRR M; eastern Iowa
Extent--small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Fayette County, Iowa, 1975.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (10 to 40 inches) (BA, Bw1, Bw2, and BC horizons);
series control section--the zone from the surface to a depth of 150 centimeters (60 inches) (Ap, BA, Bw1, Bw2, BC, C1 and C2 horizons).
Diagnostic horizons and features recognized in this pedon:
ochric epipedon--the zone from the surface to a depth of 15 centimeters (0 to 6 inches) (Ap horizon);
cambic horizon--the zone from a depth of 15 to 104 centimeters (6 to 41 inches) (BA, Bw1, Bw2, and BC horizons);
udic moisture regime.
Cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Taxonomy version--second edition, 1999.
The gray colors described in this pedon were not used in the classification of this soil as they are considered to be inherited from a relict deoxidized and leached weathering zone
ADDITIONAL DATA:
Complete physical and chemical data are available in R. J. Kuehls M. S. thesis, Iowa State University, Ames, Iowa.