LOCATION ORWOOD IAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Orwood silt loam, on a southwest-facing, convex slope of about 4 percent, in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 15 centimeters (0 to 6 inches); dark brown (10YR 3/3) silt loam; moderate fine granular structure; friable; common fine and medium roots; neutral; clear smooth boundary. [15 to 25 centimeters (6 to 10 inches) thick]
BE--15 to 25 centimeters (6 to 10 inches); brown (10YR 4/3) silt loam; moderate fine and medium subangular blocky structure; friable; common fine roots; many distinct dark brown (10YR 3/3) clay films on faces of peds; slightly acid; clear smooth boundary. [10 to 15 centimeters (4 to 6 inches) thick]
Bt1--25 to 56 centimeters (10 to 22 inches); dark yellowish brown (10YR 4/4) silt loam; moderate medium subangular blocky structure; friable; common fine roots; many distinct faint brown (10YR 4/3) clay films on faces of peds; moderately acid; gradual smooth boundary.
Bt2--56 to 109 centimeters (22 to 43 inches); yellowish brown (10YR 5/4) loam; moderate medium subangular blocky structure; friable; common fine roots; many distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; moderately acid; gradual smooth boundary.
Bt3--109 to 140 centimeters (43 to 55 inches); yellowish brown (10YR 5/4) loam; weak medium subangular blocky structure; friable; few distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; strongly acid; gradual smooth boundary. [Combined thickness of the Bt horizon is 61 to 122 centimeters (24 to 48 inches).]
BC--140 to 203 centimeters (55 to 80 inches); yellowish brown (10YR 5/4) silt loam; weak coarse subangular blocky structure; friable; slightly acid.
TYPE LOCATION: Major Land Resource Area (MLRA) 105; Winneshiek County, Iowa; about 2 miles north and 1 1/2 miles east of Kendallville; about 668 meters (2,190 feet) south and 49 meters (160 feet) east of the northwest corner of section 23, T. 100 N., R. 10 W; USGS Cresco NE quadrangle; lat. 43 degrees 27 minutes 57.3 seconds N. and long. 92 degrees 0 minutes 31.9 seconds W, NAD 83.
RANGE IN CHARACTERISTICS:
Depth to carbonates--greater than 152 centimeters (60 inches)
Content of clay in the particle-size control section (weighted average)--18 to 30 percent
Content of sand in the particle-size control section (weighted average)--15 to 45 percent, dominantly fine sand
Rock fragment content--0 percent
A or Ap horizon:
Hue--10YR
Value--2 or 3
Chroma--1 to 3
Texture--silt loam or loam
Clay content--15 to 27 percent
Sand content--15 to 45 percent
Reaction--moderately acid to neutral
E horizon (if present):
Hue--10YR
Value--4
Chroma--2 or 3
Texture--silt loam or loam
Clay content--15 to 27 percent
Sand content--15 to 45 percent
Reaction--moderately acid to neutral
BE horizon:
Hue--10YR
Value--4
Chroma--3
Texture--silt loam
Clay content--15 to 27 percent
Sand content--15 to 45 percent
Reaction--strongly acid to neutral
Bt horizon:
Hue--10YR
Value--4 or 5
Chroma--3 to 6
Texture--silt loam, loam, or clay loam
Clay content--18 to 30 percent
Sand content--15 to 45 percent
Reaction--strongly acid to neutral
BC or C horizon:
Hue--10YR
Value--4 or 5
Chroma--4 or 6
Texture--silt loam or loam
Clay content--15 to 27 percent
Sand content--15 to 40 percent
Reaction--strongly acid to moderately alkaline
COMPETING SERIES: These are the
Angus,
Argyle,
Blooming,
Caleb,
Cortland,
Gara,
Koronis,
Lester,
Newcomer,
Racine,
Sebbo,
Taopi,
Waucoma, and
Winneshiek series.
Angus--have carbonates within depths of 61 to 137 centimeters (24 to 54 inches)
Argyle--have matrix hues of 5YR or redder in the lower half of the series control section
Blooming--have carbonates within depths of 89 to 165 centimeters (35 to 65 inches) and have 2 to 6 percent rock fragments in the lower two thirds of the series control section
Caleb--have more than 40 percent sand in the lower third of the series control section
Cortland--have a rock fragment content of 1 to 20 percent in the lower two thirds of the series control section
Gara--have a clay content of 30 to 35 percent in the particle-size control section
Koronis--have carbonates within depths of 41 to 91 centimeters (16 to 36 inches) and have a rock fragment content of 2 to 15 percent in the series control section
Lester--have carbonates within depths of 51 to 137 centimeters (20 to 54 inches) and have a rock fragment content of 1 to 8 percent in the series control section
Newcomer--have a paralithic contact with sandstone within depths of 51 to 102 centimeters (20 to 40 inches)
Racine--have carbonates within depths of 102 to 178 centimeters (40 to 70 inches) and have a rock fragment content of 2 to 12 percent in the lower two thirds of the series control section
Sebbo--have redoximorphic features in the lower third of the series control section
Taopi--have a rock fragment content of 10 to 40 percent in the lower third of the series control section
Waucoma--have a lithic contact with limestone within depths of 102 to 152 centimeters (40 to 60 inches)
Winneshiek--have a lithic contact with limestone within depths of 51 to 102 centimeters (20 to 40 inches)
GEOGRAPHIC SETTING:
Parent material--eolian sediments
Landform--side slopes, interfluves and crests on dissected till plains
Slopes--2 to 30 percent
Elevation--259 to 488 meters (850 to 1600 feet) above sea level
Mean annual air temperature--7 to 10 degrees C (45 to 50 degrees F)
Mean annual precipitation--76 to 86 centimeters (30 to 34 inches)
Frost-free period--150 to 180 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Coggon,
Dubuque,
Fayette, and
Worthen soils.
Coggon--are in landscape positions similar to those of the Orwood soils, have a saturated zone within depths of 0.6 to 1.2 meters (2 to 4 feet) during the wettest periods of most years and have a rock fragment content of 2 to 10 percent in the lower half of the series control section
Dubuque--are at lower elevations on side slopes and have a lithic contact with limestone within depths 51 to 102 centimeters (20 to 40 inches)
Fayette--are in landscape positions similar to those of the Orwood soils and have a sand content of less than 5 percent in the particle-size control section
Worthen--are in lower elevations on base slopes and have mollic epipedons 61 to 91 centimeters (24 to 36 inches) thick
DRAINAGE AND PERMEABILITY:
Drainage class--well drained--saturation does not occur within a depth of 1.8 meters (6 feet) during the during the wettest periods of most years
Saturated hydraulic conductivity--moderately high or high
Surface runoff potential--very low to high
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, soybeans, small grains, and legume hays. Steeper sloping areas are wooded or pastured. The native vegetation is big bluestem, little bluestem, switchgrass, other grasses of the tall grass prairie and deciduous trees, dominantly oak and hickory.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic section(s)--Wisconsin driftless section, Dissected till plains
MLRA(s)--Eastern Iowa and Minnesota Till Prairies (104), Northern Mississippi Valley Loess Hills (105), Illinois and Iowa Deep Loess and Drift (108)
LRR M; northeastern Iowa
Extent--moderate
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Winneshiek County, Iowa, 1974.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 75 centimeters (10 to 30 inches) (Bt1 and Bt2 horizons);
series control section--the zone from the surface to a depth of 150 centimeters (59 inches) (Ap, Bt1, Bt2, Bt3, and BC 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);
argillic horizon--the zone from a depth of 25 to 140 centimeters (10 to 55 inches (Bt1, Bt2, and Bt3 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.