LOCATION CORWITH IA+MN
Established Series
Rev. RGJ-RJV-AWY
01/2011
CORWITH SERIES
The Corwith series consists of deep, somewhat poorly drained soils that formed in medium-textured sediments. These soils are on uplands, glacial lake plains, and outwash areas. Slopes are convex and range from 1 to 3 percent. Mean annual temperature is about 8 degrees C. Mean annual precipitation is about 740 millimeters.
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Aquic Hapludolls
TYPICAL PEDON: Corwith loam--on a 2 percent convex slope in a cultivated field. (All colors are for moist soil unless otherwise stated.)
Ap--0 to 23 centimeters (0 to 9.1 inches); black (10YR 2/1) and very dark brown (10YR 2/2) loam, very dark gray (10YR 3/1) dry; some mixing of very dark grayish brown (10YR 3/2); weak fine and very fine granular structure; friable; few fine roots; slightly effervescent; moderately alkaline; abrupt smooth boundary.
A--23 to 36 centimeters (9.1 to 14.2 inches); very dark grayish brown (10YR 3/2) loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure parting to weak fine and very fine granular; friable; few fine roots; very dark gray (10YR 3/1) coats on faces of peds; brown (10YR 4/3) and dark yellowish brown (10YR 4/4) worm castings; strongly effervescent; moderately alkaline; gradual smooth boundary.
BA--36 to 46 centimeters (14.2 to 18.1 inches); very dark grayish brown (10YR 3/2) silt loam, dark grayish brown (10YR 4/2) in lower part; weak very fine subangular blocky structure parting to weak fine and medium granular; friable; few fine roots; very dark gray (10YR 3/1) coats on faces of peds; brown (10YR 4/3) and dark yellowish brown (10YR 4/4) worm castings; strongly effervescent; moderately alkaline; gradual smooth boundary.
Bw1--46 to 61 centimeters (18.1 to 24 inches); yellowish brown (10YR 5/4) and dark grayish brown (10YR 4/2) silt loam; weak medium subangular blocky structure parting to weak fine and very fine subangular blocky; friable; very dark grayish brown (10YR 3/2) worm castings; strongly effervescent; moderately alkaline; gradual smooth boundary.
Bw2--61 to 79 centimeters (24 to 31.1 inches); mottled yellowish brown (10YR 5/6 and 5/4), dark grayish brown (10YR 4/2), and brown (10YR 4/3) silt loam high in sand; weak medium subangular blocky structure; friable; few fine tubular pores; few fine faint strong brown (7.5YR 5/6) oxide concretions; common fine distinct pale brown (10YR 6/3) redoximorphic concentrations; strongly effervescent; moderately alkaline; gradual wavy boundary.
C--79 to 152 centimeters (31.1 to 59.8 inches); mottled light brownish gray (2.5Y 6/2), pale brown (10YR 6/3), and light yellowish brown (2.5Y 6/4) silt loam; massive; friable; few fine tubular pores; few fine and medium dark reddish brown (5YR 3/4) concretions (oxides); few fine light gray (10YR 7/2) calcium carbonate accumulations in thread-like streaks; few fine prominent brown (7.5YR 4/4) and strong brown (7.5YR 5/6), and common medium prominent yellowish brown (10YR 5/8) redoximorphic concentrations; strongly effervescent; moderately alkaline.
TYPE LOCATION: Major Land Resource Area (MLRA) 103-Central Iowa and Minnesota Till Prairies, Kossuth County, Iowa subset; about 5 miles east and 3 miles north of West Bend; 2,440 feet north and 315 feet east of the southwest corner of sec. 25, T. 95 N., R. 30 W.; USGS West Bend topographic quadrangle; lat. 43 degrees 0 minutes 56.4 seconds N. and long. 94 degrees 20 minutes 42 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--25 to 49 centimeters (9.8 to 19.3 inches)
Depth to carbonates--at the surface and throughout the profile
Clay content in the particle-size control section (weighted average)--12 to 18 percent
Sand content in the particle-size control section (weighted average)--5 to 15 percent fine sand or sand that is coarser than fine (about 50 to 80 percent of the sand in the control section is very fine sand).
Ap or A horizon:
Hue--10YR or is Neutral
Value--2 or 3
Chroma--0 to 2
Texture--loam or silt loam that has a high content of sand
Clay content--12 to 20 percent
Sand content--10 to 40 percent
Reaction--slightly alkaline or moderately alkaline
Coarse fragments--0 percent
Thickness--20 to 45 centimeters (7.9 to 17.7 inches)
An AB horizon is in some pedons.
BA horizon:
Hue--10YR or 2.5Y
Value--2 to 4
Chroma--1 or 2
Texture--loam or silt loam that has a high content of very fine sand
Clay content--12 to 20 percent
Sand content--5 to 40 percent
Reaction--slightly alkaline or moderately alkaline
Coarse fragments--0 percent
Thickness--0 to 15 centimeters (0 to 5.9 inches)
Bw and BC horizon (if present):
Hue--10YR to 5Y
Value--4 or 5
Chroma--2 to 6
Texture--loam, silt loam, or rarely very fine sandy loam
Clay content--12 to 20 percent
Sand content--5 to 55 percent
Reaction--slightly alkaline or moderately alkaline
Coarse fragments--0 percent
Thickness--25 to 50 centimeters (9.8 to 19.7 inches)
C horizon:
Hue--10YR to 5Y
Value--4 to 6
Chroma--2 to 8
Texture--silt loam or very fine sandy loam but ranges to include loamy fine or medium sand; in some pedons, strata of silty clay loam are present
Clay content--5 to 15 percent
Sand content--30 to 80 percent
Reaction--slightly alkaline or moderately alkaline
In some pedons, glacial till is present at a depth as shallow as 125 centimeters (49.2 inches).
COMPETING SERIES:
There are no other series in the same family
GEOGRAPHIC SETTING:
Parent material--medium-textured sediments that mantle the Early Wisconsin till plain
Landform--slightly convex slopes on glacial moraines
Slope--1 to 3 percent
Elevation--300 to 400 meters above sea level
Mean annual air temperature--6 to 10 degrees C.
Mean annual precipitation--585 to 890 millimeters
Frost-free period--155 to 200 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Near the type location, these are the Canisteo, Fieldon, Kossuth, and Talcot soils.
All of these soils occur on lower landscape positions and are saturated at the surface to within 0.3 meters (11.8 inches) of the surface in an undrained condition
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained--in a natural condition, saturation typically occurs at a depth between 0.3 and 1.0 meters (11.8 to 39.4 inches)
Saturated hydraulic conductivity--moderately high (1.0 to 10.0 micrometers per second)
USE AND VEGETATION:
Most areas of Corwith soils are cultivated. Corn and soybeans are the principal crops. The native vegetation is big bluestem, indiangrass, switchgrass, and other grasses of the tall grass prairie.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic section--Western lake section
MLRA--Central Iowa and Minnesota Till Prairies (103)
LRR M; southern Minnesota and north central Iowa
Extent--small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Kossuth County, Iowa, 1980.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (9.8 to 39.4 inches)
Series control section--the zone from the surface of the soil to a depth of 150 centimeters (59.1 inches)
Diagnostic horizons and features recognized in this pedon include:
mollic epipedon--the zone from the surface to a depth of 46 centimeters (18.1 inches) (Ap, A, and BA horizons)
cambic horizon--the zone from a depth of 46 to 79 centimeters (18.1 to 31.1 inches) (Bw1 and Bw2 horizons)
udic moisture regime
Taxonomy version--Keys to Soil Taxonomy, eleventh edition, 2010.
Cation-exchange activity class in inferred from lab data from similar soils in the surrounding area.
It is questionable if the zone within 75 centimeters (29.5 inches) of the surface in this profile meets the requirements of an Aquic sub group. This profile may better fit the Oxyaquic sub group. Until another profile can be located and described, the classification will remain the same.
National Cooperative Soil Survey
U.S.A.