LOCATION LETRI MN+IAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Endoaquolls
TYPICAL PEDON: Letri clay loam on a dissected moraine in a cultivated field. (Colors are for moist soil conditions unless otherwise stated.)
Ap--0 to 9 inches; very dark gray (10YR 3/1) clay loam, dark gray (10YR 4/1) dry; weak fine granular structure; friable; common very fine and fine roots; many faint black (N 2/0) organic coats on faces of peds; noneffervescent; slightly alkaline; abrupt smooth boundary.
A1--9 to 16 inches; black (10YR 2/1) clay loam, very dark gray (10YR 3/1) dry; weak medium granular structure; friable; common very fine and fine roots; neutral; clear smooth boundary.
A2--16 to 20 inches; very dark gray (10YR 3/1) clay loam, dark gray (10YR 4/1) dry; weak very fine subangular blocky structure; friable; common very fine and fine roots; many faint dark olive gray (5Y 3/2) organic coats on faces of peds; common fine prominent olive gray (5Y 4/2) redox depletions; slightly effervescent; slightly alkaline; clear smooth boundary.
Bg--20 to 26 inches; olive gray (5Y 4/2) clay loam; weak fine subangular blocky structure; friable; common faint dark olive gray (5Y 3/2) and common faint black (10YR 2/1) organic coats on faces of peds; common fine prominent light olive brown (2.5Y 5/4) redox concentrations; slightly effervescent; slightly alkaline; abrupt wavy boundary.
2Bkg1--26 to 31 inches; olive gray (5Y 5/2) clay loam; weak fine and medium subangular blocky structure; friable; common fine and medium very pale brown (10YR 8/2) soft calcium carbonate threads; about 12 percent gravel; common fine prominent light olive brown (2.5Y 5/4) redox concentrations; strongly effervescent; moderately alkaline; clear wavy boundary.
2Bkg2--31 to 41 inches; grayish brown (2.5Y 5/2) clay loam; weak medium subangular blocky structure; firm; common fine and medium very pale brown (10YR 8/3) soft calcium carbonate threads; about 10 percent gravel; common fine prominent strong brown (7.5YR 5/6) and many fine and medium prominent light olive brown (2.5Y 5/6) redox concentrations; strongly effervescent; moderately alkaline; clear smooth boundary.
2C--41 to 80 inches; light olive brown (2.5Y 5/4) clay loam; massive; firm; about 3 percent gravel; many fine and medium prominent grayish brown (2.5Y 5/2) redox depletions; strongly effervescent; slightly alkaline.
TYPE LOCATION: Clay County, Iowa, about 390 feet east and 1500 feet north of the southwest corner of section 23, T. 97 N., R. 38 W., Waterford Township; USGS Everly, Iowa Topographic Quadrangle; latitude 43 degrees 12 minutes 09 seconds N., longitude 95 degrees 18 minutes 26 seconds W., NAD27.
RANGE IN CHARACTERISTICS: The depth to free carbonates ranges from 16 to 30 inches. The mollic epipedon ranges from 14 to 24 inches in thickness. These soils lack or have an upper sediment that is less than 30 inches thick and it overlies glacial till. The upper sediment contains from 0 to 4 percent by volume of coarse fragments and the glacial till contains 2 to 8 percent of coarse fragments. A stone line ranging to as much as 4 inches in thickness and containing up to 40 percent by volume of coarse fragments commonly is at the contact of the two sediments. The coarse fragments are of mixed lithology. The 10 to 40 inch control section averages between 24 and 33 percent clay and typically 20 to 30 percent of fine sand and coarser and ranging from 15 to 35 percent.
The A horizon has hue of 10YR, 2.5Y, 5Y or is neutral, value of 2 or 3, and chroma of 0 or 1. It is silty clay loam or clay loam. It ranges from slightly acid to mildly alkaline.
The Bg horizon has hue to 2.5Y, or 5Y, value of 4 or 5, and chroma of 1 or 2. It is silty clay loam or clay loam. It is neutral to slighlty alkaline.
The 2Bg horizon has hue to 2.5Y, or 5Y, value of 4 or 5, and chroma of 1 or 2. It is clay loam. It is neutral to slightly alkaline.
The 2Bkg horizon has hue to 2.5Y, or 5Y, value of 4 to 6, and chroma of 1 or 2. It is clay loam or loam. It is slightly alkaline to moderately alkaline and the calcium carbonate equivalent ranges from 15 to 30 percent.
The 2C or 2BC horizon has hue of 2.5Y, 5Y or less commonly 10YR, value of 4 to 6, and chroma of 2 through 4. It is clay loam or loam averaging between 25 and 33 percent clay. It is slighlty alkaline or moderately alkaline and the calcium carbonate equivalent ranges from 12 to 20 percent. The moist bulk density is 1.6 to 1.8 g/cc. The moist consistency is typically firm.
COMPETING SERIES: These are the Clyde, Faxon, Marengo, Selma, Selmass, Tripoli, and Webster series. Clyde soils have carbonates below depths of 45 inches. Faxon soils have bedrock at depths of 20 to 40 inches. Marengo soils have carbonates below depths of 40 inches. Selma and Selmass soils do not have firm glacial till in the lower third of the series control section.
GEOGRAPHIC SETTING: These soils have plane or slightly concave slopes with gradient of less than 2 percent on dissected ground moraines. They typically formed in a thin layer of erosional sediments that apparently are mixed with loess at least in some places or loamy ablation till. These sediments are underlain by calcareous, firm, loam or clay loam till. Mean annual air temperature is about 45 to 52 degrees F, and mean annual precipitation is about 25 to 30 inches. Frost free days range from 145 to 160. Elevation above sea level ranges from 900 to 1,200 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Everly, Storden, and Wilmonton soils that form a drainage catena. The moderately well drained Everly, well drained Storden and somewhat poorly drained Wilmonton soils are on higher lying or more sloping positions.
DRAINAGE AND PERMEABILITY: Poorly drained. Surface runoff is low. Permeability is moderately slow. Undrained areas have season high saturation at depths of 0 to 1 foot during the wettest parts of noraml years.
USE AND VEGETATION: Mostly cropped to corn and soybeans. Native vegetation is a wet association of the tall grass prairie plant formation.
DISTRIBUTION AND EXTENT: MLRA-107. Northwestern Iowa. Inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Nobles County, Minnesota, 1970.
REMARKS: Diagnostic horizons and properties recognized in this pedon are: mollic epipedon - the zone from the surface to a depth of 20 inches (Ap, A1 and A2 horizons), cambic horizon - the zone from 20 inches to 41 inches (Bg, 2Bkg1 and 2Bkg2 horizons), Aquic moisture regime.
ADDITIONAL DATA: Refer to MAES Central File Code No. 930 for results of some laboratory analysis of a representative pedon of this series.