LOCATION PONCA NEEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Hapludolls
TYPICAL PEDON: Ponca silty clay loam - on a 14 percent convex west-facing slope in a cultivated field. When described, the soil was moist throughout. (Colors are for moist soils unless otherwise stated.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silty clay loam, grayish brown (10YR 5/2) dry; weak fine granular structure; hard, friable; neutral; abrupt smooth boundary. (7 to 10 inches thick)
Bw1--8 to 10 inches; dark grayish brown (10YR 4/2) silty clay loam, light brownish gray (10YR 6/2) dry; weak medium prismatic structure parting to weak medium and fine subangular blocky; hard, friable; neutral; clear wavy boundary.
Bw2--10 to 18 inches; brown (10YR 5/3) silty clay loam, light brownish gray (10YR 6/2) dry; weak coarse prismatic structure parting to moderate medium and fine subangular blocky; hard, friable; neutral; abrupt smooth boundary. (Combined thickness of Bw horizon ranges from 7 to 15 inches.)
BC--18 to 24 inches; brown (10YR 5/3) silty clay loam, light brownish gray (10YR 6/2) dry; few medium distinct reddish brown (5YR 5/4) iron masses the the matrix; the matrix color and iron accumulations are relict redoximorphic features; weak medium prismatic structure; hard, friable; few medium and small lime concretions; many small dark concretions; violent effervescence; moderately alkaline; clear wavy boundary. (2 to 7 inches thick)
C1--24 to 30 inches; yellowish brown (10YR 5/4) silty clay loam, pale brown (10YR 6/3) dry; many medium distinct reddish brown (5YR 5/4) iron masses the the matrix; the matrix color and iron accumulations are relict redoximorphic features; massive; hard, friable; a few dark lime concretions; strong effervescence; moderately alkaline; clear wavy boundary. (0 to 10 inches thick)
C2--30 to 80 inches; yellowish brown (10YR 5/4) silty clay loam, pale brown (10YR 6/3) dry; massive; hard, friable; strong effervescence; moderately alkaline.
TYPE LOCATION: Douglas County, Nebraska; about 2 1/2 miles south and 1 mile west of Bennington; 150 feet west and 2,376 feet north of the southeast corner, sec. 28, T. 16 N., R. 11 E.
RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 16 to 32 inches. The depth to free calcium carbonate ranges from 14 to 24 inches. The mollic epipedon is 7 to 10 inches thick.
The A horizon has hue of 10YR, value of 2 or 3 and 3 through 5 dry, and chroma of 2 or 3. Texture is silty clay loam or silt loam. Reaction is slightly acid or neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 5 or 6 dry, and chroma of 2 through 4. Texture is silty clay loam or silt loam. Reaction is neutral or slightly alkaline.
The BC horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 5 or 6 dry, and chroma of 2 through 4. Texture is silty clay loam or silt loam. Reaction is slightly alkaline or moderately alkaline. Relic iron masses of reddish or yellowish brown are few to common.
The C horizon has hue of 10YR or 2.5Y, value of 5 or 6 and 6 or 7 dry, and chroma of 2 through 4. Texture is silty clay loam or silt loam. Reaction is mildly or moderately alkaline. Relic mottles of reddish brown are in some pedons.
COMPETING SERIES: These are the Corboldt, Exira, Galva, Keg, Marshall, Monona, Nira, Northboro, Port Byron, Raddle, Sac, Salix, and Truman series. Similar soils are the Moody and Nora soils. Corboldt soils have thicker sola and have free carbonates at deeper depths. Exira, Galva, Keg, Marshall, Monona, Nira, Port Byron, Sac, and Salix soils are leached of calcium carbonates to depths greater than 24 inches. In addition, in Sac soils, the lower part of the sola is formed in glacial till. Northboro soils have redder hues in the B horizon and more sand throughout the solum. Raddle soils typically have thicker sola, tend to be more acid, and are deeper to free carbonates. Truman soils have a thicker mollic epipedon. Moody and Nora soils are drier for longer periods.
GEOGRAPHIC SETTING: Ponca soils are on gently sloping to steep uplands having a convex surface. The slope is typically 6 to 11 percent, but ranges from 2 to 30 percent. The soils formed in loess. The mean annual temperature ranges from 51 to 55 degrees F, and the mean annual precipitation ranges from 26 to 32 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Marshall and Monona soils and the Ida and Judson soils. Ida soils do not have a mollic epipedon, have free carbonates within a depth of 10 inches and have a thinner solum and typically are on steeper slopes. Judson soils have a thicker mollic epipedon and are below Ponca soils. Marshall and Monona soils are on similar landscapes.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is moderately low to high depending primarily on slope and cover. Permeability is moderate.
USE AND VEGETATION: Largely cropped to corn, soybeans, and alfalfa. The steeper slopes are commonly in native rangeland, consisting mainly of mid and tall grasses.
DISTRIBUTION AND EXTENT: Eastern and southeastern Nebraska, perhaps northeast Kansas and western Iowa. The Ponca soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Douglas County, Nebraska, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon--the zone from the surface to a depth of 8 inches (Ap horizon); cambic horizon--the zone from 8 to 18 inches (Bw1 and Bw2 horizons).