LOCATION CORNELL IAEstablished Series
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.