LOCATION KNOX MO+IA KSEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Mollic Hapludalfs
TYPICAL PEDON: Knox silt loam, on a convex slope of 7 percent. (Colors are for moist soil unless otherwise stated.)
A--0 to 18 centimeters; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak very fine granular structure; friable; many roots; few wormholes and worm casts; moderately acid; clear smooth boundary. (12 to 24 centimeters thick)
E--18 to 30 centimeters; brown (10YR 4/3) silt loam; weak very fine granular structure; friable; many roots; few wormholes and wormcasts; moderately acid; clear smooth boundary. (0 to 20 centimeters thick)
Bt1--30 to 58 centimeters; dark yellowish brown (10YR 4/4) silty clay loam; moderate very fine subangular blocky structure; firm; few roots; many faint brown (10YR 4/3) clay films on faces of peds; grayish brown (10YR 5/2) silt coats on faces of some peds: moderately acid; clear smooth boundary.
Bt2--58 to 89 centimeters; dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; firm; few roots; common faint brown (10YR 4/3) clay films on faces of some peds and old root channels; moderately acid; gradual smooth boundary.
Bt3--89 to 155 centimeters; dark yellowish brown (10YR 4/4) silty clay loam; moderate coarse subangular blocky structure; friable; common faint clay films on the faces of some peds; moderately acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 80 to 140 centimeters.)
BC--155 to 180 centimeters; dark yellowish brown (10YR 4/4) silt loam; weak coarse prismatic structure; friable; few faint clay flows on vertical faces of peds; neutral.
TYPE LOCATION: Major Land Resource Area (MLRA) 107B-Iowa and Missouri Deep Loess Hills, Jackson County, Missouri subset; about 3 miles north of Buckner; Located about 330 feet north and 260 feet west of the southeast corner of section 34, T. 51 N., R. 30 W.; USGS Buckner topographic quadrangle; lat. 39 degrees 10 minutes 59 seconds N. and long. 94 degrees 11 minutes 43 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Depth to carbonates--greater than 180 centimeters
Clay content in the particle-size control section (weighted average)--25 to 35 percent
Sand content in the particle-size control section (weighted average)--less than 5 percent
Rock fragment content--0 percent
A or Ap (when present) horizon:
Hue--10YR
Value--2 or 3
Chroma--2 or 3
Texture--silt loam or silty clay loam
Clay content--18 to 30 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral
E (when present) horizon:
Hue--10YR
Value--4 or 5
Chroma--2 to 4
Texture--silt loam or silty clay loam
Clay content--18 to 30 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral
In cultivated areas, the E horizon may be entirely incorporated into the Ap horizon
Some pedons have a BE horizon
Bt horizon:
Hue--7.5YR or 10YR
Value--4 or 5
Chroma--3 to 6
Texture--silt loam or silty clay loam
Clay content--25 to 35 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral
BC and C (when present) horizon:
Hue--7.5YR or 10YR
Value--4 or 5
Chroma--3 to 6
Texture--silt loam
Clay content--18 to 27 percent
Sand content--less than 5 percent
Reaction--slightly acid to neutral
Some pedons have redoximorphic features
COMPETING SERIES: These are the
Batavia,
Bowes,
Churchtown,
Deroin,
Downs,
Ella,
Festina,
Frankville,
Gladek,
Greenbush,
Harvard,
Hersey,
Luana,
Mannon,
Massbach,
Mellott,
Mt. Carroll,
Myrtle,
Nasset,
Newhouse,
Oak Center,
Watkins,
Waubeek, and
Yutan series.
Batavia--have more than 10 percent sand in the lower third of the series control section
Bowes--have more than 30 percent sand and have a rock fragment content of more than 15 percent in the lower third of the series control section
Churchtown--have 10 to 55 percent sand in the upper half of the series control section
Deroin--have a sand content that averages 5 to 30 percent in the particle-size control section
Downs--have a clay content that averages 24 to 32 percent, have a sand content that averages less than 10 percent in the particle-size control section and have a reaction range of strongly acid to slightly acid in the lower third of the series control section
Ella--have a sand content that averages 15 to 60 percent in the lower third of the series control section
Festina--have a sand content that averages more than 10 percent throughout the series control section
Frankville--have a lithic contact with limestone within a depth of 100 centimeters
Gladek--have carbonates within a depth of 150 centimeters
Greenbush--have a frequently saturated zone at a depth of 1.2 meters centimeters during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Harvard--have a sand content of more than 15 percent in the lower one third of the series control section
Hersey--have a rock fragment content of 2 to 15 percent and have a sand content that averages more than 15 percent in the lower third of the series control section
Luana--have a rock fragment content of 10 to 35 percent in the lower third of the series control section
Mannon--have a clay content that averages 18 to 27 percent in the particle-size control section and have a frequently saturated zone at a depth of 1.2 meters during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation
Massbach--have a paralithic contact with calcareous silty clay or clay shale within a depth of 150 centimeters
Mellott--have carbonates within a depth of 150 centimeters and have a sand content of 35 to 65 percent in the lower third of the series control section
Mt. Carroll--have a clay content that averages 18 to 24 percent in the particle-size control section
Myrtle--have a rock fragment content of 1 to 5 percent in the series control section
Nassett--have a lithic contact with limestone within a depth of 150 centimeters
Newhouse--have a clay content that averages 18 to 27 percent in the particle-size control section and have 5 to 35 percent chert and sandstone fragments in the lower third of the series control section
Oak Center--have a sand content of more than 35 percent within a depth of 150 centimeters
Watkins--have a clay content that averages 30 to 35 percent in the particle-size control section
Waubeek--have a sand content of 35 to 65 percent in the lower third of the series control section
Yutan--have a clay content of 35 to 40 percent in the ochric epipedon
GEOGRAPHIC SETTING:
Parent material--loess
Landform--strongly dissected hills and bluffs bordering the Missouri River Valley and its tributaries
Slope--2 to 35 percent
Elevation--100 to 475 meters above sea level
Mean annual air temperature--8 to 14 degrees C
Mean annual precipitation--660 to 1,220 millimeters
Frost-free period--155 to 230 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Leta,
Higginsville,
Sibley and
Snead soils.
Leta--are on lower landscape positions on flood plains have a mollic epipedon 25 to 60 centimeters thick and have carbonates within a depth of 25 centimeters
Higginsville--are on slightly higher landscape positions on side slopes and have a mollic epipedon 25 to 60 centimeters thick
Sibley--are on higher landscape positions on interfluves and side slopes and have a mollic epipedon 60 to 92 centimeters thick
Snead--are on lower landscape positions on side slopes and have a paralithic contact with shale within a depth of 100 centimeters
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained--a frequently saturated zone does not occur within a depth of 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
USE AND VEGETATION:
More gently sloping areas are cultivated. The principal crops are corn and soybeans. More steeply sloping areas are hayland or pastureland. The native vegetation is mixed hardwood trees and big bluestem, little bluestem, switchgrass, and other grasses of the tall grass prairie.
DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic sections--Dissected till plains and Till plains
MLRAs--Iowa and Missouri Deep Loess Hills (107B) and Central Mississippi Valley Wooded Slopes, Western Part (115B)
LRR M; northwestern and central Missouri, southwestern Iowa, and northeastern Kansas
Extent--large
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Cooper County, Missouri, 1909.
REMARKS:
Particle-size control section--the zone from a depth of 30 to 80 centimeters;
series control section--the zone from the surface to a depth of 180 centimeters.
Diagnostic features and horizons recognized in this series include:
ochric epipedon--the zone from the surface of the soil to a depth of 30 centimeters (A and E horizons);
argillic horizon--the zone from a depth of 30 to 155 centimeters (Bt1, Bt2 and Bt3 horizons);
udic moisture regime.
Cation-exchange activity class is supported by lab data from National Soil Survey Laboratory; Lincoln, Nebraska.
Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.
ADDITIONAL DATA:
Laboratory data--National Soil Survey Laboratory; Lincoln, Nebraska; user pedon ids 87KS043003 and 97IA047005; (http://ssldata.sc.egov.usda.gov/).