LOCATION MONONA IA+KS MO NEEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Hapludolls
TYPICAL PEDON: Monona silt loam, on a slope of 1 percent, in a cultivated field, at an elevation of 418 meters (1,370 feet) above sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 centimeters (0 to 7 inches); very dark brown (10YR 2/2) silt loam, very dark grayish brown (10YR 3/2) dry; weak fine subangular blocky structure parting to weak fine granular; friable; few very fine pores; slightly acid; clear smooth boundary.
A--18 to 38 centimeters (7 to 15 inches); very dark brown (10YR 2/2) and dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak very fine subangular blocky structure parting to weak very fine granular; friable; few very fine pores; slightly acid; clear smooth boundary. [Combined thickness of the A horizon is 25 to 61 centimeters (10 to 24 inches).]
Bw1--38 to 53 centimeters (15 to 21 inches); brown (10YR 4/3) silt loam; weak fine subangular blocky structure; friable; common very fine pores; neutral; gradual smooth boundary.
Bw2--53 to 76 centimeters (21 to 30 inches); brown (10YR 4/3) silt loam; weak fine subangular blocky structure; friable; many very fine pores; few very fine dark concretions (oxides); neutral; gradual smooth boundary. [Combined thickness of the Bw horizon is 30 to 114 centimeters (12 to 45 inches).]
C--76 to 152 centimeters (30 to 60 inches); brown (10YR 4/3) silt loam; massive; very friable; few very fine pores; many very fine dark concretions (oxides); common very fine distinct brown (7.5YR 4/4) relict redoximorphic concentrations; few fine distinct grayish brown (2.5Y 5/2) relict redoximorphic depletions; neutral grading with depth to slightly alkaline.
TYPE LOCATION: Major Land Resource Area (MLRA) 107; Harrison County, Iowa; about 7 miles east of Woodbine; about 67 meters (220 feet) north and 318 meters (1,044 feet) east of southwest corner of section 13, T. 80 N., R. 41 W.; USGS Portsmouth quadrangle; lat. 41 degrees 43 minutes 59 seconds N. and long. 95 degrees 34 minutes 22 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--25 to 61 centimeters (10 to 24 inches)
Depth to relict redoximorphic features--56 to 165 centimeters (22 to 65 inches)
Depth to carbonates--61 to more than 203 centimeters (24 to more than 80 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 5 percent
Clay content decreases regularly with depth
A or Ap horizon:
Hue--10YR
Value--2 or 3
Chroma--1 to 3
Texture--silt loam or silty clay loam
Clay content--20 to 35 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral
AB or BA horizon (if it occurs):
Hue--10YR
Value--2 or 3
Chroma--2 or 3
Texture--silt loam or silty clay loam
Clay content--20 to 30 percent
Sand content--less than 5 percent
Reaction--slightly acid or neutral
Thickness--0 to 6 inches
Bw horizon:
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--silt loam or silty clay loam
Clay content--20 to 27 percent
Sand content--less than 5 percent
Reaction--slightly acid or neutral
BC horizon (if it occurs):
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--silt loam
Clay content--18 to 26 percent
Sand content--less than 5 percent
Reaction--neutral or slightly alkaline
Thickness--0 to 12 inches
Redoximorphic features present in this horizon are believed to be relict and not considered to be related to present day saturation
C horizon:
Hue--10YR
Value--4 or 5
Chroma--3 to 6
Texture--silt loam
Clay content--18 to 24 percent
Sand content--less than 10 percent
Calcium carbonate equivalent--0 to 25 percent
Reaction--neutral to moderately alkaline
Redoximorphic features present in this horizon are believed to be relict and not considered to be related to present day saturation
Some pedons have sandy and gravelly sediments within a depth of 60 inches
COMPETING SERIES: These are the
Annieville,
Biggsville,
Dinsmore,
Exira,
Galva,
Keg,
Marshall,
Northboro,
Ponca,
Port Byron,
Raddle,
Salix, and
Truman series.
Annieville--have a sand content of more than 10 percent within depths of 102 to 152 centimeters (40 to 60 inches)
Biggsville--have zones within a depth of 152 centimeters (60 inches) that are frequently saturated for periods longer than one month in most years
Dinsmore--have a sand content of 30 to 70 percent within depths of 102 to 152 centimeters (40 to 60 inches)
Exira--have a clay content of 30 to 35 percent in the particle-size control section and have many or common redoximorphic features within depths of 76 centimeters (30 inches)
Galva--have a clay content of 30 to 35 percent in the particle-size control section and have carbonates within depths of 81 to 183 centimeters (32 to 72 inches)
Keg--have a sand content of 10 to 35 percent in the lower half of the series control section
Marshall--have a clay content of 27 to 35 percent in the particle-size control section
Northboro--have cambic horizons with matrix hues of 5YR or 7.5YR
Ponca--have carbonates within a depth of 61 centimeters (24 inches)
Port Byron--are more acid throughout the series control section
Raddle--are more acid throughout the series control section and have a sand content of more than 5 percent in the lower half of the series control section
Salix--have a sand content of 15 to 60 percent in the lower third of the series control section and have carbonates within depths of 51 to 91 centimeters (20 to 36 inches)
Truman--have a sand content of more than 10 percent in the series control section
GEOGRAPHIC SETTING:
Parent material--loess
Landform--interfluves and side slopes on dissected till plains and risers and treads on loess covered stream terraces
Slopes--0 to 40 percent
Elevation--335 to 457 meters (1,100 to 1,500 feet) above sea level
Mean annual air temperature--8 to 12 degrees C (47 to 54 degrees F)
Mean annual precipitation--66 to 81 centimeters (26 to 32 inches)
Frost-free period--145 to 175 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Dow,
Ida,
Napier, and
Steinauer soils.
Dow--are at lower elevations on side slopes, have carbonates within a depth of 25 centimeters (10 inches), and have a matrix chroma of 2 in the lower two thirds of the series control section
Ida--are at lower elevations on side slopes, have carbonates within a depth of 25 centimeters (10 inches), and have a matrix chroma greater than 2 in the lower two thirds of the series control section
Napier--are at lower elevations on base slopes and have a mollic epipedon 61 to 102 centimeters (24 to 40 inches) thick
Steinauer--are at lower elevations on side slopes, have carbonates within a depth of 25 centimeters (10 inches), and have a sand content of 20 to 52 percent in the particle-size control section
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 most years
Saturated hydraulic conductivity--moderately high
Surface runoff potential--negligible to high
USE AND VEGETATION:
Most areas are cultivated. Some steeply sloping areas are forested or pastured. The principal crops are corn, soybeans, small grains, and hay. The native vegetation is big bluestem, little bluestem, indiangrass, switchgrass, and other grasses of the tall grass prairie.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic section--Dissected till plains
MLRAs--Nebraska and Kansas Loess-Drift Hills (106) and Iowa and Missouri Deep Loess Hills (107)
LRR M; western Iowa, northeastern Kansas, eastern Nebraska, and possibly northwestern Missouri along the Missouri River
Extent--large
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Monona County, Iowa, 1957.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (10 to 40 inches) (A, Bw1, Bw2, and C horizons);
series control section--the zone from the surface to a depth of 150 centimeters (0 to 60 inches) (Ap, A, Bw1, Bw2, and C horizons).
Diagnostic horizons and features recognized in this pedon:
mollic epipedon--the zone from the surface to a depth of 38 centimeters (15 inches) (Ap and A horizons);
cambic horizon--the zone from a depth of 38 to 76 centimeters (15 to 30 inches) (Bw1 and Bw2 horizons);
udic moisture regime.
Cation-exchange class is supported by lab sample number S87IA-155-003, NSSL.
Taxonomy version--Keys to Soil Taxonomy, ninth edition, 2003
The loess deposits are typically 24 to 32 feet thick but is as thin as 6 feet on some convex side slopes and as thin as 5 feet on loess covered stream terraces
ADDITIONAL DATA:
Laboratory data--Iowa State University, Ames, IA, many pedons
Laboratory data--National Soil Survey Laboratory, Lincoln, Nebraska, many pedons (http://ssldata.sc.egov.usda.gov/)