LOCATION RATHBUN                 IA

Established Series
Rev. JDH-MRL-AWY
11/2010

RATHBUN SERIES

The Rathbun series consists of deep, somewhat poorly drained soils formed in loess. These soils occur on summits of interfluves, side slopes, and treads on high stream terraces. Slope ranges from 2 to 9 percent. Mean annual temperature is about 11 degrees C. Mean annual precipitation is about 950 millimeters.

TAXONOMIC CLASS: Fine, smectitic, mesic Aquertic Hapludalfs

TYPICAL PEDON: Rathbun silt loam - pasture, with a 6 percent convex south-facing slope. (Colors are for moist soil unless otherwise stated.)

A--0 to 10 centimeters; very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; moderate fine granular structure; friable; few coarse and many fine and medium roots; strongly acid; abrupt smooth boundary.

E--10 to 33 centimeters; yellowish brown (10YR 5/4) silt loam, light yellowish brown (10YR 6/4) dry; moderate thin platy structure; friable; few coarse and common fine roots; very strongly acid; abrupt smooth boundary.

BE--33 to 43 centimeters; yellowish brown (10YR 5/4) silty clay loam; moderate fine subangular blocky structure; friable; common fine roots; few light yellowish brown (10YR 6/4), dry silt coats on all faces of peds; few fine distinct dark grayish brown (10YR 4/2) redoximorphic depletions; very strongly acid; clear smooth boundary.

Btg1--43 to 58 centimeters; dark grayish brown (10YR 4/2) silty clay; moderate fine angular and subangular blocky structure; firm; common fine roots; common distinct dark gray (10YR 4/1)) clay films on all faces of peds; few dark brown (7.5YR 3/2) spherical iron-manganese concretions; few fine distinct grayish brown (2.5Y 5/2) redoximorphic depletions; very strongly acid; gradual smooth boundary.

Btg2--58 to 74 centimeters; dark grayish brown (10YR 4/2) silty clay; moderate fine angular blocky structure; firm; common fine roots; common distinct dark gray (10YR 4/1) clay films on all faces of peds; few dark brown (7.5YR 3/2) spherical iron-manganese concretions; common fine distinct grayish brown (2.5Y 5/2) redoximorphic depletions; very strongly acid; gradual smooth boundary.

Btg3--74 to 91 centimeters; grayish brown (2.5Y 5/2) and dark grayish brown (10YR 4/2) silty clay; moderate medium angular blocky structure; firm; common fine roots; common distinct dark gray (10YR 4/1) clay films on all faces of peds; few dusky red (2.5YR 3/2) spherical iron-manganese concretions; common fine distinct dark yellowish brown (10YR 4/4) and common fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; moderately acid; gradual smooth boundary.

Btg4--91 to 109 centimeters; grayish brown (2.5Y 5/2) silty clay loam; moderate medium angular and subangular blocky structure; firm; few fine roots; common distinct gray (2.5Y 5/1) clay films on all faces of peds; few dusky red (2.5YR 3/2) and dark reddish brown (5YR 2.5/2) spherical iron-manganese concretions; common fine distinct dark yellowish brown (10YR 4/4) and common fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; moderately acid; gradual smooth boundary.

Btg5--109 to 142 centimeters; light brownish gray (2.5Y 6/2) and yellowish brown (10YR 5/4) silty clay loam; weak fine prismatic structure parting to moderate fine subangular blocky; firm; few fine roots; common distinct gray (2.5Y 5/1) clay films on all faces of peds; few distinct light gray (10YR 7/1), dry silt coats on all faces of peds; few dark reddish brown (5YR 2.5/2) spherical iron-manganese concretions; common fine distinct strong brown (7.5YR 5/6) redoximorphic concentrations; moderately acid; gradual smooth boundary.

BCg--142 to 165 centimeters; light brownish gray (2.5Y 6/2) and strong brown (7.5YR 5/6) silty clay loam; weak medium prismatic structure; friable; few fine roots; few light gray (10YR 7/1), dry silt coats on vertical faces of peds; few dark reddish brown (5YR 2.5/2) spherical iron-manganese concretions; common fine distinct yellowish brown (10YR 5/4) redoximorphic concentrations; slightly acid; gradual smooth boundary.

Cg--165 to 200 centimeters; light brownish gray (2.5Y 6/2) and strong brown (7.5YR 5/6) silty clay loam; massive; friable; few fine roots; few dark reddish brown (5YR 2.5/2) spherical iron-manganese concretions; common fine distinct yellowish brown (10YR 5/4) redoximorphic concentrations; slightly acid.

TYPE LOCATION: Major Land Resource Area (MLRA) 109-Iowa and Missouri Heavy Till Plain, Appanoose County, Iowa; about 2 miles west and 3 miles south of Cincinnati; 65 feet south and 460 feet west of the northeast corner, section 20, T. 67 N., R. 18 W; USGS Mendota topographic quadrangle; lat. 40 degrees 35 minutes 41 seconds N. and long. 92 degrees 56 minutes 42 seconds W. NAD 83.

RANGE IN CHARACTERISTICS:
Depth to carbonates--greater than 200 centimeters
Clay content in the particle control section (weighted average)--38 to 48 percent
Sand content in the particle size control section (weighted average)--1 to 5 percent
Rock fragment content--0 percent

A horizon:
Hue--10YR
Value--3 or 4
Chroma--1 or 2
Texture--silt loam
Clay content--18 to 26 percent
Sand content--1 to 5 percent
Reaction--strongly acid to slightly acid
Thickness--5 to 13 centimeters

Ap horizon (when present):
Hue--10YR
Value--4 or 5
Chroma--1 to 3
Texture--silt loam or silty clay loam
Clay content--18 to 35 percent
Sand content--1 to 5 percent
Reaction--strongly acid to slightly acid
Thickness--15 to 25 centimeters

E horizon:
Hue--10YR
Value--4 or 5
Chroma--2 to 4
Texture--silt loam
Clay content--18 to 26 percent
Sand content--1 to 5 percent
Reaction--very strongly acid or strongly acid
Thickness--0 to 30 centimeters

Where the soil is cultivated, the E horizon is partially or completely mixed into the Ap horizon

BE horizon:
Hue--10YR
Value--4 or 5
Chroma--3 or 4
Texture--silty clay loam
Clay content--27 to 38 percent
Sand content--1 to 5 percent
Reaction--very strongly acid or strongly acid
Thickness--0 to 20 centimeters

Btg horizon (upper part):
Hue--10YR or 2.5Y
Value--4 to 6
Chroma--2
Texture--silty clay loam or silty clay
Clay content--40 to 58 percent
Sand content--1 to 5 percent
Reaction--very strongly acid or strongly acid
Special features--the upper Btg horizon has a subhorizon with a clay content of 48 to 58 percent; some horizon between the A or Ap horizon and a depth of 75 centimeters has a matrix chroma greater than 2 in more than 40 percent of the matrix

Btg horizon (lower part):
Hue--10YR to 2.5Y
Value--5 or 6
Chroma--2 to 6
Texture--silty clay loam or silty clay
Clay content--32 to 42 percent
Sand content--1 to 5 percent
Reaction--strongly acid to slightly acid
Thickness (entire Btg horizon)--75 to 130 centimeters

BCg horizon:
Hue--7.5YR to 5Y
Value--5 or 6
Chroma--1 to 6
Texture--silt loam or silty clay loam
Clay content--24 to 34 percent
Sand content--1 to 5 percent
Reaction--moderately acid or slightly acid
Thickness--10 to 30 centimeters

C horizon:
Hue--7.5YR to 5Y
Value--5 or 6
Chroma--1 to 6
Texture--silt loam or silty clay loam
Clay content--24 to 34 percent
Sand content--1 to 5 percent
Reaction--moderately acid or slightly acid

COMPETING SERIES: These are the Armstrong, Clafork, Malmo, Mystic, Otoe, and Pering series.
Armstrong--have more than 15 percent sand in the series control section
Clafork--have a fragic horizon as shallow as a depth of 76 centimeters
Malmo--have more than 20 percent sand in the series control section
Mystic--have more than 5 percent sand in the series control section
Otoe--have carbonates as shallow as 76 centimeters
Pering--differentia is not clear at this time. Deactivating the Pering series and re-correlating it to Rathbun may be an option to consider.

GEOGRAPHIC SETTING:
Parent material--loess
Landform--summits of interfluves, side slopes, and treads on stream terraces
Slope--2 to 9 percent
Elevation--200 to 300 meters above sea level
Mean annual air temperature--9 to 12 degrees C
Mean annual precipitation--865 to 1040 millimeters
Frost free period--175 to 210 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Near the type location, these are the Ashgrove, Beckwith, Keswick, and Lindley soils.
Ashgrove--are at lower landscape positions and are saturated at the surface to within .3 meter of the surface for some period in most years
Beckwith-- are at higher landscape positions and are saturated at the surface to within .3 meter of the surface for some period in most years
Keswick--are at lower landscape positions and have a sand content that averages 20 to 45 percent in the particle size control section
Lindley--are at lower landscape positions and have a sand content that averages 20 to 40 percent in the particle size control section

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained--a frequently saturated zone occurs within depths of 0.3 to 1.0 meter during most years; this saturation is considered perched
Saturated hydraulic conductivity--0.01 to 0.10 micrometers per second

USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, soybeans, small grains, hay and pasture. A few areas are in woodland. Native vegetation is oak-hickory forest.

DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowland
Physiographic sections--Dissected till plains
MLRA--Iowa and Missouri Heavy Till Plain (109)
LRR M--southern Iowa and possibly northern Missouri
Extent--moderate

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana

SERIES ESTABLISHED: Appanoose County, Iowa, 1970.

REMARKS:
Particle size control section--the zone from a depth of 43 to 93 centimeters;
Series control section--the zone from the surface to a depth of 150 centimeters

Diagnostic horizons and features recognized in the pedon include:
Ochric epipedon--the zone from the surface to a depth of 43 centimeters (A, E, and BE horizons);
argillic horizon--the zone from a depth of 43 to 142 centimeters (Btg1, Btg2, Btg3, Btg4, and Btg5 horizons);
udic moisture regime

This update relocates the type location to better represent the central concept of the Rathbun series. The series has been reclassified because it does not meet the criteria for an Aqualf.

Taxonomy version--Keys to Soil Taxonomy, eleventh edition, 2010

ADDITIONAL DATA:
Laboratory data--National Soil Survey Laboratory, Lincoln Nebraska, Pedon ID numbers 69IA007004 and 69IA185002 (http://ssldata.sc.egov.usda.gov/).

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National Cooperative Soil Survey
U.S.A.