LOCATION GILLIAM MOEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Fluvaquentic Hapludolls
TYPICAL PEDON: Gilliam silty clay loam - on a 0.5 percent slope in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; weak fine granular structure; friable; common fine roots; slight effervescence; slightly alkaline; abrupt smooth boundary.
A1--7 to 11 inches; very dark grayish brown (10YR 3/2) silty clay loam, grayish brown (10YR 5/2) dry; weak fine granular structure; friable; common fine roots; slight effervescence; slightly alkaline; abrupt smooth boundary.
A2--11 to 15 inches; very dark gray (10YR 3/1) silty clay loam, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; firm; few fine roots; slight effervescence; slightly alkaline; abrupt smooth boundary. (Combined thickness of the A horizon is 10 to 24 inches.)
C--15 to 22 inches; dark grayish brown (10YR 4/2) silty clay loam; appears massive but has distinct bedding planes; friable; few fine roots; slight effervescence; slightly alkaline; abrupt smooth boundary. (Combined thickness of the C horizon is 6 inches to many feet.)
Ab--22 to 26 inches; very dark gray (10YR 3/1) silty clay loam; weak fine subangular blocky structure; firm; slight effervescence; slightly alkaline; abrupt smooth boundary. (0 to 8 inches thick)
Cg--26 to 60 inches; stratified dark grayish brown (10YR 4/2) and very dark grayish brown (10YR 3/2) silt loam and silty clay loam; thin lenses of very dark gray (10YR 3/1) silty clay; appears massive, but has distinct bedding planes; friable; strong effervescence; moderately alkaline.
TYPE LOCATION: Jackson County, Missouri; about 4 miles northeast of Atherton; 600 feet south and 2500 feet west of the northeast corner, sec. 15, T. 51 N., R. 30 W.
RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon ranges from 10 to 24 inches. The average clay content of the 10 to 40 inch particle size control section is 18 to 35 percent. Thin strata of coarser or finer texture occur in the lower part of some pedons. Reaction commonly is slightly alkaline or moderately alkaline, but is neutral in the surface layer of some pedons.
The Ap or A horizon has hue of 10YR or 2.5Y, value of 2 or 3 and chroma of 1 or 2. It is silt loam, silty clay loam, or loam.
The C horizon is stratified and has hue of 10YR or 2.5Y, value of 3 to 5 and chroma of 1 or 2. It commonly is silt loam or silty clay loam, but may be loam. When present, redoximorphic features have hue of 7.5YR to 2.5Y, value of 4 to 6 and chroma of 1 to 8.
The Ab horizon has color and texture similar to the A horizon. Some pedons do not have this horizon.
COMPETING SERIES: These are the Fatima, Radford, and Tice series. The Fatima, Radford, and Tice series do not have free carbonates.
GEOGRAPHIC SETTING: Gilliam soils are on flood plains along major streams. These soils formed in calcareous alluvium. The slope gradient is 0 to 2 percent. The mean annual temperature ranges from 52 to 57 degrees F, and mean annual precipitation ranges from 30 to 40 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the coarse-silty Haynie, clayey over loamy Leta, coarse-silty over clayey Modale, sandy Sarpy, clayey Waldron, and coarse-loamy over clayey Waubonsie soils. Haynie soils are on slightly higher landscapes. Leta, Modale, Waldron, and Waubonsie soils are on similar landscapes. Sarpy soils generally are closer to the streams.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Runoff is slow. Permeability is moderate. Flooding is rare or common. In undisturbed areas, a perched water table has an upper limit of 1.5 to 3.0 feet during November to June in most years.
USE AND VEGETATION: Soils are cropped to alfalfa, corn, soybeans, and wheat. Native vegetation is tall grasses, willow, and cottonwood.
DISTRIBUTION AND EXTENT: Floodplains of the Missouri River. Gilliam soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Jackson County, Missouri, 1982.
REMARKS: Diagnostic horizons and features recognized in this series are: mollic epipedon - the zone from the surface of the soil to a depth of 15 inches (Ap, A, and A2 horizons).