LOCATION HUMESTON IA+MOEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Argiaquic Argialbolls
TYPICAL PEDON: Humeston silty clay loam, on a nearly level bottom land, in a pasture. (Colors are for moist soil unless otherwise noted.)
A1--0 to 20 centimeters; black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine subangular blocky structure; friable; slightly acid; clear smooth boundary.
A2--20 to 33 centimeters; very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; weak fine subangular blocky structure parting to weak fine granular; friable; common distinct gray (10YR 6/1) and light gray (10YR 7/1) dry, silt coats on faces of peds; moderately acid; clear smooth boundary. (Combined thickness of the A horizon is 25 to 40 centimeters.)
E1--33 to 41 centimeters; dark gray (10YR 4/1) silt loam; moderate thin platy structure; friable; common distinct light gray (10YR 7/1) dry silt coats on faces of peds; strongly acid; clear smooth boundary.
E2--41 to 56 centimeters; dark gray (10YR 4/1) silt loam; moderate thin platy structure; friable; common distinct light gray (10YR 7/1) dry silt coats on faces of peds; moderately acid; clear smooth boundary. (Combined thickness of the E horizon is 15 to 36 centimeters.)
BE--56 to 66 centimeters; mottled very dark gray (10YR 3/1) and dark gray (10YR 4/1) silty clay loam; weak medium subangular blocky structure; friable; common distinct light gray (10YR 7/1) dry silt coats on faces of peds; moderately acid; clear smooth boundary. (0 to 20 centimeters thick)
Btg1--66 to 102 centimeters; black (10YR 2/1) silty clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; firm; common distinct black (N 2/0) clay films on faces of peds; slightly acid; gradual smooth boundary.
Btg2--102 to 127 centimeters; very dark gray (10YR 3/1) silty clay; moderate medium prismatic structure; firm; few distinct black (10YR 2/1) clay films on faces of peds; slightly acid; gradual smooth boundary. (Combined thickness of the Btg horizon is 40 to 90 centimeters.)
BCg--127 to 160 centimeters; mottled very dark gray (10YR 3/1) and dark grayish brown (10YR 4/2) silty clay loam; weak medium prismatic structure; firm; few fine distinct light olive brown (2.5Y 5/4) redoximorphic concentrations; slightly acid.
TYPE LOCATION: Major Land Resource Area (MLRA) 108D-Illinois and Iowa Deep Loess Hills, Western Part, Union County, Iowa subset; about 2 miles south of Kent; located about 2,190 feet south and 1,970 feet west of the northeast corner of section 30, T. 71 N., R. 31 W.; USGS Kent topographic quadrangle; lat. 40 degrees 55 minutes 20 seconds N. and long. 94 degrees 27 minutes 33 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon--25 to 40 centimeters
Depth to carbonates--more than 180 centimeters
Clay content of the particle-size control section (weighted average)--35 to 42 percent
Sand content of the particle-size control section (weighted average)--less than 10 percent
A or Ap horizon:
Hue--10YR
Value--2 or 3
Chroma--1
Texture--silt loam or silty clay loam
Clay content--20 to 30 percent
Sand content--less than 10 percent
Reaction--strongly acid to neutral
E horizon:
Hue--10YR
Value--3 to 5
Chroma--1
Texture--silt loam
Clay content--15 to 26 percent
Sand content--less than 10 percent
Reaction--very strongly acid to moderately acid
BE horizon (when present):
Hue--10YR
Value--2 to 4
Chroma--1
Texture--silty clay loam or silt loam
Clay content--24 to 35 percent
Sand content--less than 10 percent
Reaction--very strongly acid to moderately acid
Btg horizon:
Hue--10YR to 5Y, or is neutral
Value--2 or 3
Chroma--0 or 1
Texture--silty clay loam or silty clay
Clay content--35 to 48 percent
Sand content--less than 10 percent
Reaction--very strongly acid to slightly acid
BCg or Cg horizon:
Hue--10YR to 5Y
Value--3 to 5
Chroma--1 or 2
Texture--silty clay loam
Clay content--30 to 38 percent
Sand content--less than 10 percent
Reaction--very strongly acid to slightly acid
COMPETING SERIES: These are the
Arbela,
Leslie, and
Tetonka series.
Arbela--have a matrix value of 4 or 5 in the argillic horizon and have a sand content of more than 5 percent in all parts of the series control section
Leslie--have a matrix value of 3 to 6 in the argillic horizon and have a sand content that averages less than 5 percent in the series control section
Tetonka--have a reaction range of neutral to moderately alkaline in the lower third of the series control section
GEOGRAPHIC SETTING:
Parent material--alluvium
Landform--concave foot slopes and slightly concave backswamps of flood plain steps and floodplains
Slope--0 to 5 percent
Mean annual air temperature--8 to 13 degrees C
Mean annual precipitation--660 to 1,040 millimeters
Frost-free period--155 to 220 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Colo,
Kennebec,
Vesser, and
Wabash soils.
Colo--are at slightly lower landscape positions on floodplains, have a mollic epipedon more than 90 centimeters thick and have a clay content that averages 27 to 35 percent in the particle-size control section
Kennebec--are at slightly higher landscape positions on floodplains and have a clay content that averages 18 to 35 percent in the particle-size control section
Vesser--are at slightly higher landscape positions on foot slopes or alluvial fans and have a clay content that averages 30 to 35 percent in the particle-size control section
Wabash--are at slightly lower landscape positions on floodplains, have a mollic epipedon 90 to 115 centimeters thick and have a clay content that averages 45 to 60 percent in the particle-size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--poorly drained--these soils are frequently saturated between the soil surface and a depth of 0.3 meter during the wettest portions of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Saturated hydraulic conductivity--1.0 to 10.00 micrometers per second in the surface and subsurface horizons and 0.01 to 1.0 micrometers per second in the argillic horizon and substratum
Flooding--rarely or occasionally flooded for brief duration from precipitation events and snowmelt
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn and soybeans. Some areas are in permanent pasture. The native vegetation is big bluestem, little bluestem, switchgrass, other grasses of the tall grass prairie and scattered deciduous trees.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowlands
Physiographic sections--Dissected till plains
MLRAs--Iowa and Missouri Deep Loess Hills (107B), Illinois and Iowa Deep Loess and Drift (108), and Iowa and Missouri Heavy Till Plain(109)
LRR M; southern Iowa and northern Missouri
Extent--moderate
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Lucas County, Iowa, 1940.
REMARKS:
Particle size control section--the zone from a depth of 66 to 116 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 (A1 and A2 horizons);
albic horizon--the zone from a depth of 33 to 56 centimeters (E1 and E2 horizons);
argillic horizon--the zone from a depth of 66 to 127 centimeters (Btg1 and Btg2 horizons);
aquic moisture regime.
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.
ADDITIONAL DATA:
Laboratory data--National Soil Survey Laboratory, Lincoln, Nebraska-user pedon id 71IA185002 (http://ssldata.sc.egov.usda.gov/).