LOCATION PORTAGE MOEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, mesic Vertic Endoaquolls
TYPICAL PEDON: Portage clay - in a cultivated field. When described, the soil was moist throughout. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 4 inches; black (10YR 2/1) clay; dark gray (10YR 4/1) dry; strong very fine subangular blocky structure; firm; moderately acid; abrupt smooth boundary.
A1--4 to 9 inches; very dark gray (10YR 3/1) clay; gray (10YR 5/1) dry; moderate very fine subangular blocky structure; firm; few fine faint dark grayish brown (10YR 4/2) iron depletions in ped interiors; moderately acid; clear smooth boundary.
A2--9 to 14 inches; very dark grayish brown (10YR 3/2) and very dark gray (10YR 3/1) clay; grayish brown (10YR 5/2) dry; moderate fine and very fine subangular blocky structure; firm; strongly acid; clear smooth boundary. (Combined thickness of the A horizon is 10 to 24 inches thick)
Bg1--14 to 24 inches; dark gray (10YR 4/1) clay; moderate fine and very fine subangular blocky structure; firm; common fine distinct brown (10YR 4/3) masses of iron accumulation in ped interiors; strongly acid; gradual smooth boundary.
Bg2--24 to 40 inches; dark gray (N 4/0) clay; moderate fine and very fine angular and subangular blocky structure; firm; few fine distinct brown (10YR 4/3) masses of iron accumulation in ped interiors; strongly acid; gradual smooth boundary.
Bg3--40 to 75 inches; dark grayish brown (2.5Y 4/2) clay; weak medium prismatic structure parting to weak fine and very fine angular and subangular blocky; firm; common fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation in ped interiors; strongly acid.
TYPE LOCATION: St. Charles County, Missouri; near Smartt Air Field; 1800 feet north and 400 feet east of the southwest corner of sec. 11, T. 48 N., R. 5 E.
RANGE IN CHARACTERISTICS: The A horizon has hue of 10YR or 2.5Y, value of 2 or 3 and chroma of 1 or 2. It commonly is clay, but includes silty clay. Reaction is moderately acid or strongly acid unless limed.
The Bg horizon has hue of 10YR to 5Y, value of 3 to 5 and chroma of 1 or 2 or is neutral with brownish masses of iron accumulation. The average clay content of the particle size control section ranges from 60 to 75 percent. Reaction commonly is strongly acid or very strongly acid, but may be moderately acid in the lower part.
COMPETING SERIES: These are the Booker and Carson series. Similar soils are the Carlow and Darwin series. Booker and Carson soils are less acid than strongly acid in the series control section. Carlow and Darwin soils average less than 60 percent clay in the particle size control section and are less acid.
GEOGRAPHIC SETTING: Portage soils are on broad, nearly level flood plains, shallow closed depressions on floodplains, oxbows and backswamps. These soils formed in clayey slack water sediments. Slope gradients range from 0 to less than 2 percent. Mean annual precipitation ranges from 33 to 43 inches, and mean annual temperature ranges from 54 to 57 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blase, Carlow, and Lomax series. Blase soils have a clayey over loamy particle size control section and are on terraces. Carlow soils contain less clay and are on similar landscapes. Lomax soils have a coarse-loamy particle size control section and are on terraces.
DRAINAGE AND PERMEABILITY: Very poorly and poorly drained. Permeability is very slow. Runoff is very slow or ponded. In undistrubed areas there is an apparent water table that has an upper limit of 0.5 to 1.0 foot above the surface where very poorly drained from November to July and 0.0 to 1.0 foot above the surface where poorly drained from November to June in most years.
USE AND VEGETATION: Most areas are used to grow wheat, soybeans, or corn, but some areas are used for pasture. Native vegetation is mainly willow, cottonwood and marsh grasses.
DISTRIBUTION AND EXTENT: Major drainages of northern Missouri. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: St. Charles County, Missouri, 1979.
REMARKS: Diagnostic horizons and features recognized in this series are: mollic epipedon - the zone from the surface of the soil to a depth of 14 inches (Ap, A1, and A2 horizons); cambic horizon - the zone from approximately 14 inches to 75 inches or more (Bg1, Bg2, and Bg3 horizons).
ADDITIONAL DATA: NSSL-RP77-MO149 lists particle size distribution, base saturation, and pH for the Portage series.