LOCATION CORNELL            IA
Established Series
MJM-RJW-TWN
10/2008

CORNELL SERIES


The Cornell series consist of very deep, moderately well drained soils that formed in 25 to 125 centimeters of loamy and silty sediments and in the underlying till. These soils occur on shoulder slopes and side slopes on dissected till plains. Slope ranges from 9 to 40 percent. Mean annual air temperature is about 8 degrees C. Mean annual precipitation is about 725 millimeters.

TAXONOMIC CLASS: Fine, smectitic, mesic Oxyaquic Vertic Argiudolls

TYPICAL PEDON: Cornell silty clay loam, on a 25 percent slope, in a pastured woodland, at an elevation of about 408 meters above mean sea level. (Colors are for moist soil unless otherwise stated.)

A1--0 to 15 centimeters; black (10YR 2/1) silty clay loam, very dark gray (10YR 3/1) dry; weak fine granular structure; friable; common fine to coarse roots; slightly acid; clear smooth boundary.

A2--15 to 28 centimeters; very dark brown (10YR 2/2) interior and black (10YR 2/1) exterior silty clay loam, grayish brown (10YR 5/2) and dark gray (10YR 4/1) dry; weak fine subangular blocky structure; friable; common fine to coarse roots; about 2 percent gravel; moderately acid; clear smooth boundary. (Combined thickness of the A horizon is 25 to 45 centimeters thick.)

AB--28 to 41 centimeters; very dark grayish brown (10YR 3/2) interior and black (10YR 2/1) and very dark brown (10YR 2/2) exterior silty clay loam, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; friable; common fine to coarse roots; about 1 percent gravel; slightly acid; clear smooth boundary. (0 to 20 centimeters thick)

Bt1--41 to 53 centimeters; brown (10YR 4/3) silty clay loam; moderate fine subangular blocky structure; firm; common fine to coarse roots; common distinct very dark grayish brown (10YR 3/2) organoargillans on faces of peds and in root channels; common fine prominent red (2.5YR 4/6) masses of iron on faces of peds; about 4 percent gravel; moderately acid; clear smooth boundary.

Bt2--53 to 76 centimeters; dark yellowish brown (10YR 4/4) clay; moderate fine prismatic structure parting to strong fine and medium subangular blocky; firm; common fine to coarse roots; few distinct very dark grayish brown (10YR 3/2) organoargillans on faces of peds and in root channels; few fine and medium red (2.5YR 4/6) masses of iron on faces of peds; common fine prominent strong brown (7.5YR 5/6) redoximorphic concentrations; common medium distinct dark grayish brown (10YR 4/2) redoximorphic depletions; about 4 percent gravel; strongly acid; clear smooth boundary.

Bt3--76 to 109 centimeters; dark yellowish brown (10YR 4/4) and yellowish brown (10YR 5/4) clay; moderate medium prismatic structure parting to strong medium angular blocky; firm; common fine to coarse roots; common distinct very dark grayish brown (10YR 3/2) organoargillans throughout; few fine and medium red (2.5YR 4/6) masses of iron on faces of peds; common fine prominent strong brown (7.5YR 4/6) and common fine distinct yellowish brown (10YR 5/6) redoximorphic concentrations on faces peds; about 6 percent gravel; strongly acid; abrupt wavy boundary. (Combined thickness of the Bt horizon is 50 to 175 centimeters.)

2Bt4--109 to 137 centimeters; dark yellowish brown (10YR 4/4) clay loam; moderate coarse prismatic structure parting to moderate medium and coarse angular blocky; firm; common fine roots between peds; few prominent very dark grayish brown (10YR 3/2) clay films on faces of peds; about 3 percent gravel; strongly effervescent; moderately alkaline; clear wavy boundary.

2Bt5--137 to 158 centimeters; yellowish brown (10YR 5/6) clay loam; weak coarse prismatic structure parting to weak coarse subangular blocky; firm; common fine roots between peds; few prominent very dark grayish brown (10YR 3/2) clay films on faces of peds; common fine prominent grayish brown (10YR 5/2) redoximorphic depletions; about 8 percent gravel; strongly effervescent; moderately alkaline; gradual wavy boundary.

2Bt6--158 to 178 centimeters; yellowish brown (10YR 5/6) clay loam; weak coarse prismatic structure parting to weak coarse subangular blocky; firm; common fine roots; few very dark grayish brown (10YR 3/2) clay films on faces of peds; about 9 percent gravel; strongly effervescent; moderately alkaline; gradual wavy boundary.

2Bt7--178 to 200 centimeters; yellowish brown (10YR 5/6) clay loam; weak very coarse prismatic structure; firm; common fine roots; few prominent very dark grayish brown (10YR 3/2) clay films on faces of peds; about 7 percent gravel; strongly effervescent; moderately alkaline.

TYPE LOCATION: Major Land Resource Area (MLRA) 107A-Iowa and Minnesota Loess Hills; Clay County, Iowa subset; about 1 mile southeast of Cornell; located about 400 feet east and 1,000 feet north of the southwest corner of section 28, T. 94 N., R. 36 W.; USGS Webb topographic quadrangle; lat. 42 degrees 55 minutes 44 seconds N. and long. 95 degrees 06 minutes 31 seconds W., NAD 83.

RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon--25 to 49 centimeters
Depth to till--25 to 125 centimeters
Depth to carbonates--100 to 150 centimeters
Clay content of the particle-size control section (weighted average)--35 to 45 percent
Sand content of the particle-size control section (weighted average)--15 to 35 percent

A, Ap (when present), and AB horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silty clay loam or clay loam
Clay--27 to 35 percent
Sand--10 to 30 percent
Rock fragment content--0 to 5 percent
Reaction--moderately acid to neutral

Bt horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 4
Texture--clay, silty clay, or silty clay loam
Clay--35 to 45 percent
Sand--15 to 30 percent total
Rock fragment content--0 to 10 percent
Reaction--very strongly acid to neutral

2Bt and 2BC (when present) horizon:
Hue--10YR or 2.5Y
Value--4 or 5
Chroma--2 to 6
Texture--loam or clay loam
Clay--24 to 33 percent
Sand--30 to 45 percent
Rock fragment content--2 to 15 percent
Reaction--neutral to moderately alkaline
Moist bulk density--1.6 to 1.8 g/cc

COMPETING SERIES: These are the Baileyville, Chillicothe, and Pawnee series.
Baileyville--have a sand content that averages 1 to 2 percent in the particle-size control section
Chillicothe--have a sand content that averages less than 10 percent in the particle-size control section
Pawnee--have a moist bulk density range of 1.40 to 1.70 g/cc in the lower third of the series control section and are in areas that have a mean annual air temperature range of 10 to 13 degrees C and a mean annual precipitation range of 710 to 1,015 millimeters

GEOGRAPHIC SETTING:
Parent material--25 to 125 centimeters of loamy and silty sediments and in the underlying till
Landform--shoulder slopes and side slopes on dissected till plains
Slope--9 to 40 percent
Elevation--340 to 520 meters above sea level
Mean annual air temperature--7 to 9 degrees C
Mean annual precipitation--660 to 790 millimeters
Frost-free period--155 to 175 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Everly, Moneta, and Sac soils.
Everly--are on higher landscape positions and have a clay content that averages 24 to 33 percent in the particle-size control section
Moneta--are on landscape positions similar to those of the Cornell soils and have carbonates within a depth of 25 centimeters
Sac--are on higher landscape positions and do not have an argillic horizon

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained--a frequently saturated zone occurs between depths of 0.75 and 1 meter during the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation, this saturation is considered perched
Saturated hydraulic conductivity--1.0 to 10.0 micrometers per second in the loamy or silty sediments and 0.10 to 1.0 micrometers per second in the underlying till

USE AND VEGETATION:
Most areas are permanent pasture or woodland. The native vegetation is 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 section--Dissected till plains
MLRA--Iowa and Minnesota Loess Hills (107A)
LRR M; northwestern Iowa
Extent--small

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

SERIES ESTABLISHED: Clay County, Iowa 2002

REMARKS:
Particle-size control section--the zone from a depth of 41 to 91 centimeters;
series control section--the zone from the surface to a depth of 200 centimeters.

Diagnostic horizons and features recognized in this pedon include:
mollic epipedon--the zone from the surface to a depth of 41 centimeters (A1, A2, and AB horizons)
argillic horizon--the zone from a depth of 41 to 200 centimeters (Bt1, Bt2, Bt3, 2Bt4, 2Bt5, 2Bt6, and 2Bt7 horizons);
udic moisture regime.

Differentia between Cornell series and Pawnee series needs further study.

Cornell soils were included with Clarion heavy subsoil variant or Storden loam on previous surveys.

Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006.

ADDITIONAL DATA:
Laboratory data--National Soil Survey Laboratory, Lincoln, Nebraska; user pedon id 94IA041001 (http://ssldata.sc.egov.usda.gov/).
Laboratory data--Iowa Agriculture Experiment Station, Iowa State University; file number 94IA041009.


National Cooperative Soil Survey
U.S.A.