LOCATION FORT DODGE IA+MNEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Cumulic Hapludolls
TYPICAL PEDON: Fort Dodge loam, on a south-facing footslope of about 2 percent, in a cultivated field. (Colors are for moist soil unless otherwise indicated.)
Ap--0 to 18 centimeters (0 to 7 inches); black (10YR 2/1) loam, very dark gray (10YR 3/1) dry; weak fine subangular blocky structure parting to weak fine granular; friable; slightly acid; abrupt smooth boundary.
A1--18 to 43 centimeters (7 to 17 inches); black (10YR 2/1) loam, very dark gray (10YR 3/1) dry; moderate fine subangular blocky structure; friable; slightly acid; gradual smooth boundary.
A2--43 to 79 centimeters (17 to 31 inches); very dark brown (10YR 2/2) loam, very dark grayish brown (10YR 3/2) dry; weak fine subangular blocky structure; friable; slightly acid; gradual smooth boundary.
A3--79 to 99 centimeters (31 to 39 inches); very dark grayish brown (10YR 3/2) loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure; friable; slightly acid; gradual smooth boundary. [Combined thickness of the A horizon is 61 to 140 centimeters (24 to 55 inches)]
Bw1--99 to 127 centimeters (39 to 50 inches); brown (10YR 4/3) loam; weak fine and medium subangular blocky structure; friable; common distinct very dark grayish brown (10YR 3/2) and dark brown (10YR 3/3) organic stains on faces of peds; about 2 percent coarse fragments in lower part; neutral; clear smooth boundary.
Bw2--127 to 147 centimeters (50 to 58 inches); dark yellowish brown (10YR 4/4) loam; weak fine and medium subangular blocky structure; friable; few fine tubular pores; common distinct dark brown (10YR 3/3) organic stains on faces of peds; about 3 percent coarse fragments; many fine shale fragments; neutral; abrupt wavy boundary. [Combined thickness of the Bw horizon is 20 to 61 centimeters (8 to 24 inches)].
2C--147 to 203 centimeters (58 to 80 inches); dark yellowish brown (10YR 4/4) loamy coarse sand; single grain; loose; about 3 percent coarse fragments; neutral.
TYPE LOCATION: Webster County, Iowa; about 280 feet east and 340 feet north of the southwest corner of section 29, T. 90 N., R. 30 W.; USGS Gilmore City SW topographic quadrangle, lat. 42 degrees 34 minutes 26 seconds N., and long. 94 degrees 25 minutes 19 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon--61 to 140 centimeters (24 to 55 inches)
Depth to loamy sand or coarser--102 to 152 centimeters (40 to 60 inches)
Depth to carbonates--102 to over 203 centimeters (40 to over 80 inches)
Clay content of the particle-size control section (weighted average)--18 to 27 percent
Sand content of the particle-size control section (weighted average)--25 to 40 percent
Ap or A horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--loam or clay loam
Clay content--18 to 30 percent
Sand content--20 to 40 percent
Rock fragment content--0 to 5 percent
Reaction--slightly acid or neutral
AB or BA horizon (when present):
Hue--10YR
Value--2 or 3
Chroma--1 to 3
Texture--loam or clay loam
Clay content--18 to 30 percent
Sand content--20 to 40 percent
Rock fragment content--0 to 5 percent
Reaction--slightly acid or neutral
Bw and BC horizon:
Hue--10YR or 2.5Y
Value--3 to 5
Chroma--3 to 6
Texture--loam, clay loam, or sandy loam
Clay content--18 to 30 percent
Sand content--25 to 60 percent
Rock fragment content--0 to 15 percent
Reaction--slightly acid or neutral
Some pedons have a Bk horizon with similar colors and textures
2C horizon:
Hue--10YR or 2.5Y
Value--3 to 6
Chroma--3 to 8
Texture--sand, coarse sand, loamy sand, loamy coarse sand or their gravelly analoges
Clay content--2 to 8 percent
Sand content--75 to 95 percent
Rock fragment content--0 to 20 percent
Reaction--slightly acid to moderately alkaline
COMPETING SERIES: These are the
Dameron,
Deloit,
Du Page,
Olmitz,
Racket,
Ross,
Spillco,
Spillville,
Terril, and
Turlin series.
Dameron-do not have coarse textured 2C horizons
Deloit and Terril--do not have a lithologic discontinuity within the series control section
Du Page--have carbonates within a depth of 25 centimeters (10 inches)
Olmitz--have a clay content of 28 to 34 percent in the particle-size control section
Racket-have greater than 11 degrees C. (54 degrees F.) mean annual air temperature
Ross--have carbonates between depths of 61 and 114 centimeters (24 to 45 inches)
Spillco--have carbonates between depths of 30 and 91 centimeters (12 to 36 inches)
Spillville and Turlin--have a frequently saturated zone within depths of 0.3 to 0.9 meters (1 to 3 feet) in normal years
GEOGRAPHIC SETTING:
Parent material--colluvium or alluvium
Landform--foot slopes, upland drainageways, alluvial fans, treads and risers on stream terraces
Slopes--0 to 9 percent
Elevation--305 to 442 meters (1,000 to 1,450 feet) above sea level
Mean annual air temperature--7 to 11 degrees C (45 to 52 degrees F)
Mean annual precipitation--580 to 860 millimeters (23 to 34 inches)
Frost-free period--145 to 180 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Associated soils include many loamy, sandy and gravelly outwash soils that typically occur above the Fort Dodge soils.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained--a frequently saturated zone does not occur within 1.8 meters (6 feet) of the surface.
Saturated hydraulic conductivity--moderately high to high in the upper part and high to very high in the sandy sediments
Surface runoff potential--low or medium, depending on slope
USE AND VEGETATION:
Most areas are cultivated. The principle crops are corn, soybeans, oats, and legume meadow. The native vegetation is big bluestem, little bluestem, switchgrass, and other grasses of the tall grass prairie.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic sections--Western lake section and Dissected till plains
MLRAs--LRR M. Central Iowa and Minnesota Till Prairies (103), Eastern Iowa and Minnesota Till Prairies (104), Iowa and Missouri Deep Loess Hills (107), Illinois and Iowa Deep Loess and Drift (108)
Extent--small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Webster County, Iowa, 2005
REMARKS:
Diagnostic horizons and features recognized in this pedon:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (10 to 39 inches) (A1, A2, and A3 horizons);
Series control section--the zone from the surface to a depth of 150 centimeters (59 inches) (Ap, A1, A2, A3, Bw1, Bw2, and 2C horizons).
Mollic epipedon--the zone from the surface to a depth of 99 centimeters (39 inches) (Ap, A1, A2, and A3 horizons);
Cambic horizon--the zone from a depth of 99 to 147 centimeters (39 to 58 inches)(Bw1 and Bw2 horizons);
Udic moisture regime.
In the past much of this series was called Terril, sandy substratum.
Taxonomy version--Keys to Soil Taxonomy, ninth edition, 2003.