LOCATION KEG IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Hapludolls
TYPICAL PEDON: Keg silt loam, on a nearly level flood plain, about 1 percent slope, in a cultivated field, at an elevation of 291 meters above sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 15 centimeters; black (10YR 2/1) silt loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure parting to weak fine granular; friable; slightly acid; abrupt smooth boundary.
A--15 to 28 centimeters; very dark brown (10YR 2/2) and very dark grayish brown (10YR 3/2) silt loam, dark grayish brown (10YR 4/2) dry; weak very fine subangular blocky structure parting to weak fine granular; friable; neutral; clear smooth boundary. (Combined thickness of the A horizon is 25 to 49 centimeters.)
Bw--28 to 56 centimeters; dark grayish brown (2.5Y 4/2) silt loam; weak very fine subangular blocky structure; friable; neutral; clear smooth boundary. (18 to 30 centimeters thick)
BC--56 to 86 centimeters; dark grayish brown (2.5Y 4/2) silt loam; weak fine subangular blocky structure; friable; few fine faint grayish brown (2.5Y 5/2) redoximorphic depletions; slightly effervescent; slightly alkaline; gradual smooth boundary. (18 to 36 centimeters thick)
C--86 to 152 centimeters; dark grayish brown (2.5Y 4/2) silt loam; massive; very friable; strongly effervescent; moderately alkaline.
TYPE LOCATION: Mills County, Iowa; about 2 miles west and 3 miles south of Glenwood; located about 100 feet south and 50 feet east of the northwest corner of section 34, T. 72 N., R. 43 W.; USGS Pacific Junction topographic quadrangle; lat. 41 degrees 0 minutes 5 seconds N. and long. 95 degrees 47 minutes 6 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--25 to 49 centimeters
Depth to carbonates--60 to 143 centimeters
Content of clay in the particle-size control section (weighted average)--18 to 26 percent
Content of sand in the particle-size control section (weighted average)--10 to 35 percent, mostly very fine sand, less than 15 percent fine sand and sand coarser than fine sand
Keg soils have an irregular decrease in clay with increasing depth
A or Ap horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silt loam
Clay content--18 to 26 percent
Sand content--10 to 30 percent
Reaction--slightly acid or neutral
AB horizon (if it occurs):
Hue--10YR
Value--3
Chroma--2 or 3
Texture--silt loam
Clay content--10 to 26 percent
Sand content--10 to 30 percent
Reaction--slightly acid or neutral
Bw horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 4
Texture--silt loam
Clay content--18 to 26 percent
Sand content--10 to 30 percent, mostly very fine sand
Reaction--neutral
Matrix chroma of 2 in the cambic horizon is not considered pedogenic and is thought to be the color derived from the parent material
Some pedons have very fine sandy loam textures below a depth of 75 centimeters
Bk horizon (if it occurs):
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 4
Texture--silt loam
Clay content--10 to 26 percent
Sand content--10 to 35 percent, mostly very fine sand
Reaction--slightly alkaline or moderately alkaline
BC horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 4
Texture--silt loam
Clay content--18 to 26 percent
Sand content--10 to 35 percent
Reaction--slightly alkaline or moderately alkaline
C horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 4
Texture--silt loam
Clay content--18 to 26 percent
Sand content--10 to 35 percent, mostly very fine sand
Reaction--slightly alkaline or moderately alkaline
Moist bulk density--1.25 to 1.40 g/cc
COMPETING SERIES: These are the
Annieville,
Biggsville,
Dinsmore,
Exira,
Galva,
Marshall,
Monona,
Northboro,
Ponca,
Port Byron,
Raddle,
Salix, and
Truman series.
Annieville--have moist bulk density of 1.6 to 1.8 g/cc in the lower part of the series control section
Biggsville--average less than 5 percent sand in the cambic horizon
Dinsmore--have a sand content of 30 to 70 percent in the lower part of the series control section
Exira--have relict redoximorphic features within a depth of 75 centimeters
Galva--have a clay content of 30 to 35 percent in the particle-size control section
Marshall--have a clay content of 27 to 34 percent in the particle-size control section and do not have carbonates within a depth of 180 centimeters
Monona--do not have a matrix chroma of 2 in the cambic horizon and have sand content of less than 5 percent in the lower part of the series control section
Northboro--have a matrix hue of 5YR or 7.5YR in the cambic horizon
Ponca--have carbonates within a depth of 60 centimeters
Port Byron--have a regular decrease in clay with increasing depth
Raddle--do not have carbonates within a depth of 180 centimeters
Salix--have a clay content of 27 to 35 percent in the particle-size control section
Truman--do not have a matrix chroma of 2 in the cambic horizon
GEOGRAPHIC SETTING:
Parent material--silty alluvium
Landform--flood plains
Slopes--0 to 2 percent
Elevation--213 to 503 meters above sea level
Mean annual air temperature--8 to 11 degrees F.
Mean annual precipitation--650 to 820 millimeters
Frost-free period--145 to 175 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Blencoe,
Cooper,
Lakeport, and
Salix soils.
Blencoe--are on lower landscape positions and have a clay content of 40 to 52 percent in the upper part of the particle-size control section
Cooper--are on lower landscape positions and have a clay content of 40 to 60 percent in the lower one third of the particle-size control section
Lakeport--are on lower landscape positions and have a clay content of 35 to 45 percent in the particle-size control section
Salix--are on lower landscape positions and have a clay content of 27 to 35 percent in the particle-size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained--a frequently saturated zone does not occur within a depth of 1.8 meters during April to June in normal years
Saturated hydraulic conductivity--4.23 to 14.11 micrometers per second (moderately high)
Surface runoff potential--negligible to low
Flooding--rare flooding for brief or very brief periods during the months of February to November resulting from precipitation events and snowmelt
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn and soybeans, small grains, and legume hay. Some areas are irrigated. 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--Dissected till plains
MLRA--Iowa and Missouri Deep Loess Hills (107)
LRR M; western Iowa, nearly level areas about midway between the river channel and the upland foot slopes on or near remnants of old meander scars of the Missouri River in Iowa and possibly adjoining states
Extent--moderate
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Woodbury County, Iowa, 1971.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters (A, Bw, BC, and C horizons);
series control section--the zone from the surface to a depth of 150 centimeters (Ap, A, Bw, BC, and C horizons).
Diagnostic horizons and features recognized in this pedon include:
mollic epipedon--the zone from the surface to a depth of 28 centimeters (Ap and A horizons);
cambic horizon--the zone from a depth of 28 to 86 centimeters (Bw and BC horizons);
udic moisture regime.
Cation-exchange activity class is supported by lab sample numbers S70IA-133-002 and S95IA-193-007, NSSL.
Taxonomy version--Keys to Soil Taxonomy, ninth edition, 2003.
Matrix chroma of 2 in the cambic horizon is not considered pedogenic and is thought to be the color derived from the parent material. These colors were not considered in the classification of this series.
ADDITIONAL DATA:
Laboratory data--Iowa State University, Ames, Iowa, pedon number 98-IA-193-029A;
Laboratory data--National Soil Survey Laboratory, Lincoln, Nebraska, pedon numbers S70IA-133-002 and S95IA-193-007, (http://ssldata.nrcs.usda.gov/).