LOCATION MCPAUL IA+MN MO NE SDEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, calcareous, mesic Mollic Udifluvents
TYPICAL PEDON: McPaul silt loam, on a nearly level flood plain, in a cultivated field, at an elevation of about 282 meters above sea level. (Colors are for moist soil unless otherwise stated)
Ap--0 to 18 centimeters; very dark grayish brown (10YR 3/2) light silt loam and a few dark grayish brown (10YR 4/2) and brown (10YR 4/3) peds; grayish brown (10YR 5/2) dry; very weak fine granular structure; very friable; slightly effervescent; neutral; abrupt smooth boundary.
C--18 to 152 centimeters; alternating layers of grayish brown (10YR 5/2) dark grayish brown (10YR 4/2), and brown (10YR 5/3) silt loam (15 percent clay), pale brown (10YR 6/3) dry; few very thin darker horizontal strata; massive with weak, thin alluvial stratification; very friable; common fine faint yellowish brown (10YR 5/8) and strong brown (7.5YR 5/6) and strong brown (7.5YR 5/8) redoximorphic concentrations in a zone between 102 and 122 centimeters; slightly effervescent; slightly alkaline.
TYPE LOCATION: Major Land Resource Area (MLRA) 107B-Iowa and Missouri Deep Loess Hills, Fremont County, Iowa subset; about 4 miles west southwest of Sidney; located about1,500 feet west and 860 feet north of the southeast corner of section 36, T. 69 N., R. 43 W.; USGS Sidney topographic quadrangle; lat. 40 degrees 43 minutes 53 seconds N. and long. 95 degrees 44 minutes and 01 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the ochric epipedon--15 to 25 centimeters
Depth to carbonates--0 to 10 centimeters
Clay content in the particle-size control section (weighted average)--10 to 18 percent
Sand content in the particle-size control section (weighted average)--5 to 15 percent
A or Ap horizon:
Hue--10Y
Value--3 or
Chroma--2 or 3
Texture--silt loam
Clay content--10 to 27 percent
Sand content--5 to 15 percent
Calcium carbonate equivalent--5 to 30 percent
Reaction--pH 6.6 to 8.4
Thickness--15 to 25 centimeters
C horizon:
Hue--10YR
Value--4 or 5
Chroma--2 or 3
Texture--silt loam, with or without strata of silty clay loam
Clay content--10 to 35 percent
Sand content--5 to 15 percent
Calcium carbonate equivalent--5 to 30 percent
Reaction--pH 7.4 to 8.4
Some pedons have buried layers, below a depth of 100 centimeters, with more than 5 percent organic matter and have more than 30 percent clay.
Some pedons have thin strata of very dark grayish brown (10YR 3/2) in the C horizon
Redoximorphic features or stains are in the lower part of the C horizon mainly on the faces of the stratification planes
COMPETING SERIES: These are the
Haynie and
Ion series.
Haynie--have a matrix hue of 2.5Y and have a sand content that averages 18 to 80 percent in the particle-size control section
Ion--have a buried horizon within a depth of 100 centimeters
GEOGRAPHIC SETTING:
Parent material--90 to 240 centimeters of calcareous, stratified alluvium from loess uplands
Landform--settling basins and near drainage channels on narrow flood plains of tributary streams that flow across the slack water areas of flood plains in river valleys
Slope--0 to 5 percent
Elevation--185 to 610 meters above sea level
Mean annual air temperature--6 to 13 degrees C
Mean annual precipitation--585 to 1,040 millimeters
Frost-free period--145 to 220 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Blake,
Kennebec,
Luton, and
Napier soils.
Blake--are on slightly lower landscape positions on flood plains and have a clay content that averages 22 to 35 percent in the particle-size control section
Kennebec--are on lower landscape positions on flood plains and have a mollic epipedon more than 100 centimeters thick
Luton--are on lower landscape positions on flood plains and have a clay content that averages 45 to 60 percent in the particle-size control section
Napier--are on higher landscape positions on adjacent foot slopes and have a mollic epipedon 60 to 100 centimeters thick
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well or somewhat poorly drained--a frequently saturated zone occurs between depths of 0.45 and 1.8 meters during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Saturated hydraulic conductivity--1.00 to 10.00 micrometers per second
Flooding--rarely flooded or occasionally flooded for very brief or brief duration
USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn and soybeans, small grain, and hay. Several areas are land-leveled and irrigated. Along narrow tributaries a few areas are used for permanent pasture because they are small or cut up badly by channels. The native vegetation is big blue stem, 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, Wisconsin driftless section, and Dissected till plains
MLRAs--Loess Uplands (102C), Northern Mississippi Valley Loess Hills (105), and
Iowa and Missouri Deep Loess Hills (107B)
LRR--M; western Iowa, southeastern Minnesota, eastern Nebraska, southeastern South Dakota, and Missouri
Extent--moderate
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana; MLRA SSO 10-6 (Atlantic, Iowa).
SERIES ESTABLISHED: Mills County, Iowa, 1941.
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 are:
ochric epipedon--zone from the surface to a depth of 18 centimeters (Ap horizon);
udic moisture regime.
These soils formed in sediments which have evident stratification and have changed little since deposition
Cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.
ADDITIONAL DATA:
Laboratory data--Iowa State University Soil Survey Laboratory, Ames, Iowa.