LOCATION ALLENDORF IAEstablished Series
TAXONOMIC CLASS: Fine-silty over sandy or sandy-skeletal, mixed, superactive, mesic Typic Hapludolls
TYPICAL PEDON: Allendorf silty clay loam, on a 3 percent convex slope, in a cultivated field, at an elevation of about 436 meters above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 23 centimeters; black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure parting to weak fine granular; friable; few fine roots; slightly acid; clear smooth boundary.
A--23 to 33 centimeters; very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; dark brown (10YR 3/3) and black (10YR 2/1) mixings; moderate fine and very fine subangular blocky structure; friable; few very fine roots; neutral; clear smooth boundary. (Combined thickness of the A horizon is 25 to 50 centimeters.)
Bw1--33 to 46 centimeters; dark yellowish brown (10YR 4/4) silty clay loam; very dark grayish brown (10YR 3/2) animal mixings; weak medium and fine subangular blocky structure; friable; few very fine roots; dark brown (10YR 3/3) coats on faces of peds; neutral; clear smooth boundary.
Bw2--46 to 69 centimeters; dark yellowish brown (10YR 4/4) silty clay loam; brown (10YR 4/3) animal mixings; weak medium prismatic structure parting to weak medium subangular blocky; friable; few very fine roots; neutral; gradual smooth boundary.
Bw3--69 to 86 centimeters; dark yellowish brown (10YR 4/4) silt loam; weak medium prismatic structure parting to weak medium subangular blocky; friable; few very fine roots; neutral; clear smooth boundary. (Combined thickness of the Bw horizon is 36 to 76 centimeters.)
2BC--86 to 94 centimeters; brown (10YR 4/3) loam; weak medium and fine subangular blocky structure; friable; few very fine roots; about 5 percent rock fragments; neutral; abrupt smooth boundary. (0 to 15 centimeters thick)
2C1--94 to 102 centimeters; brown (10YR 4/3) very gravelly loamy coarse sand; single grain; loose; few very fine roots; few calcium carbonate accumulations; about 50 percent rock fragments; strongly effervescent; moderately alkaline; abrupt smooth boundary.
2C2--102 to 152 centimeters; yellowish brown (10YR 5/4) gravelly sand; single grain; loose; few very fine roots in the upper part; about 30 percent rock fragments; strongly effervescent; moderately alkaline.
TYPE LOCATION: Major Land Resource Area (MLRA) 107-Iowa and Missouri Deep Loess Hills, Osceola County, Iowa subset; about 2.5 miles south of May City; located about 700 feet east and 500 feet south of the northwest corner of section 28, T. 98 N., R. 39 W; USGS May City topographic quadrangle; lat. 43 degrees 16 minutes 59 seconds N. and 95 degrees 27 minutes 53 seconds W., NAD83.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--25 to 50 centimeters
Thickness of silty material--75 to 100 centimeters
Depth to carbonates--75 to 100 centimeters
Clay content in the upper two thirds of the particle-size control section (weighted average)--27 to 30 percent
Clay content in the lower third of the particle-size control section (weighted average)--2 to 10 percent
Sand content of the upper two thirds of the particle-size control section (weighted average)--5 to 15 percent
Sand content of the lower third of the particle-size control section (weighted average)--80 to 95 percent
Ap or A horizon:
Hue--10YR
Value--2 or 3
Chroma--1 to 3
Texture--silty clay loam or silt loam
Clay content--24 to 32 percent
Sand content--5 to 15 percent
Rock fragment content--0 percent
Reaction--moderately acid to neutral
Some pedons have an AB or BA horizon
Bw horizon:
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--silty clay loam in the upper part and silty clay loam or silt loam in the lower part
Clay content--27 to 32 percent in the upper part and 24 to 30 percent in the lower part
Sand content--5 to 15 percent
Rock fragment content--0 percent
Reaction--moderately acid to moderately alkaline
2BC horizon (when present):
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--loam or sandy loam
Clay content--18 to 24 percent
Sand content--45 to 75 percent
Rock fragment content--0 to 10 percent
Reaction--slightly acid to slightly alkaline
2C horizon:
Hue--10YR or 2.5Y
Value--4 to 6
Chroma--3 to 6
Texture--gravelly loamy coarse sand, very gravelly loamy coarse sand, gravelly sand, loamy sand, or sand
Clay content--less than 10 percent
Sand content--more than 80 percent
Rock fragment content--10 to 60 percent
Reaction--slightly alkaline or moderately alkaline
COMPETING SERIES: These are the
Arthur,
Baytown, and
Waukegan series.
Arthur--do not have rock fragments in the lower third of the series control section
Baytown--have a paralithic contact with sandstone within a depth of 100 centimeters
Waukegan--do not have carbonates within a depth of 100 centimeters
GEOGRAPHIC SETTING:
Parent material--75 to 100 centimeters of loess or silty and loamy alluvium over sandy sediments
Landform--treads and risers on stream terraces
Slope--0 to 9 percent
Elevation--427 to 488 meters above sea level
Mean annual air temperature--7 to 11 degrees C
Mean annual precipitation--660 to 760 millimeters
Frost-free period--140 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Coland,
Everly, and
Wadena soils.
Coland--are at lower landscape positions on flood plains and are frequently saturated at the soil surface during the wettest periods of normal years
Everly--are at higher landscape positions on ground moraines and till plains and average more than 15 percent sand in the particle-size control section
Wadena--are in landscape positions similar to the Allendorf soils and average more than 25 percent sand in the particle-size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained--a frequently saturated zone does not occur within 1.8 meters in normal years
Saturated hydraulic conductivity--1.00 to 10.00 micrometers per second (moderately high) in the silty sediments and 100.00 to 705.00 micrometers per second (very high) in the underlying sandy and gravelly sediments
Surface runoff potential--negligible to medium
Flooding--rarely flooded for brief or very brief duration
USE AND VEGETATION:
Most areas are cultivated. Corn and soybeans are the principal crops. 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
MLRAs--Iowa and Missouri Deep Loess Hills (107)
LRR M; western and northwestern Iowa
Extent--small
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Osceola County, Iowa, 1985.
REMARKS:
Particle-size control section--the zone from a depth of 25 to 100 centimeters;
series control section--the zone from the surface to a depth of 150 centimeters.
Diagnostic horizons and features recognized in this pedon include:
mollic epipedon--the zone from the surface to a depth of 33 centimeters (Ap and A horizons);
cambic horizon--the zone from a depth of 33 to 94 centimeters (Bw1, Bw2, Bw3, 2BC horizons);
udic moisture regime.
Particle size data for the typical pedon are available at the Iowa State University Soil Survey Laboratory.
Cation-exchange class is inferred from lab data for similar soils in the surrounding area.
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.