LOCATION MARION MOEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aquertic Chromic Hapludalfs
TYPICAL PEDON: Marion silt loam - on a 2 percent convex slope in forest. (Colors are for moist soil unless otherwise stated.)
A--0 to 3 inches; grayish brown (10YR 5/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine granular structure; very friable; common very fine and few fine roots;very strongly acid; abrupt smooth boundary (1 to 3 inches thick)
E--3 to 11 inches; light brownish gray (10YR 6/2) silt loam; weak thin platy structure; very friable; common fine roots; common fine distinct light yellowish brown (10YR 6/4) and brownish yellow (10YR 6/6) masses of iron accumulation throughout; few fine iron and manganese stains; extremely acid; abrupt smooth boundary. (4 to 12 inches thick)
Bt1--11 to 17 inches; yellowish brown (10YR 5/4) silty clay; moderate medium subangular blocky structure; firm; few very fine roots; common distinct clay films on faces of peds and few gray clay masses; common fine distinct grayish brown (10YR 6/2) iron depletions and strong brown (7.5YR 5/6) masses of iron accumulation throughout; very strongly acid; clear wavy boundary.
Bt2--17 to 27 inches; yellowish brown (10YR 5/4) silty clay; moderate medium subangular blocky structure; firm; few very fine roots; common distinct clay films on faces of peds; few fine distinct grayish brown (10YR 5/2) iron depletions and strong brown (7.5YR 5/6) masses of iron accumulation throughout; very strongly acid; clear wavy boundary.
Btg1--27 to 41 inches; light brownish gray (10YR 6/2) silty clay loam; weak medium prismatic structure parting to weak medium subangular blocky; friable; few fine roots; few faint clay films on faces of peds; common fine distinct strong brown (7.5YR 5/6) and reddish yellow (7.5YR 6/6) masses of iron accumulation throughout; few fine iron and manganese stains; very strongly acid; clear wavy boundary.
Btg2--41 to 52 inches; light brownish gray (10YR 6/2) silty clay loam; weak very fine subangular blocky structure; firm; few very fine roots; few faint clay films on faces of peds; common fine distinct brown (7.5YR 5/4) and few fine distinct yellowish red (5YR 5/6) masses of iron accumulation throughout; common iron and manganese stains; common very fine sand grains; very strongly acid; clear wavy boundary. (Combined thickness of the Bt and Btg horizons is 25 to 48 inches.)
2BCg--52 to 60 inches; light gray (10YR 7/2) silt loam; weak very fine subangular blocky structure; friable; few very fine roots; few faint clay films along root channels; common fine distinct brownish yellow (10YR 6/6 and 10YR 6/8)) masses of iron accumulation throughout; few fine iron and manganese stains; moderately acid.
TYPE LOCATION: Boone County, Missouri; about 3 miles south and 4 miles west of Centralia; 1,200 feet east and 700 feet north of the southwest corner of sec. 25, T. 51 N., R. 12 W; Centralia USGS quadrangle; lat. 37 degrees 10 minutes 18 seconds N. and long. 92 degrees 12 minutes 29 seconds W.
RANGE IN CHARACTERISTICS: Depth to the base of the argillic horizon is 30 to 60 inches. The particle-size control averages less than 10 percent sand. An abrupt textural change is at depths of 5 to 18 inches.
The A or Ap horizon has value of 3 to 6 and chroma of 2 or 3. Surface horizons when mixed to a depth of 6 inches have value of 4 or higher. The E horizon has hue of 10YR or 2.5Y, value of 5 to 7 and chroma of 2 or 3. Reaction is extremely acid to neutral.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6 and chroma of 3 or 4. The upper 10 inches of the Bt horizon commonly has dominant chroma of more than 2 in both the matrix and on faces of peds, but may be 2 when lacking accumulations of iron. The Btg horizon has hue of 10YR or 5YR, value of 5 or 6 and dominant chroma of 2 or less. It is silty clay or silty clay loam. The upper 20 inches of the argillic horizon averages between 45 and 60 percent clay and less than 10 percent sand. Reaction commonly is extremely acid to strongly acid, but it is moderately acid in the lower part of some pedons.
The 2BCg or 2Cg horizon, where present below depths of 40 inches, has hue of 10YR to 2.5Y, value of 4 to 7, and chroma of 1 or 2. It is silty clay loam or silt loam. Reaction is strongly acid to slightly acid.
COMPETING SERIES: These are the Colp, Galland, Gorin, Keswick and Weller series. Colp soils have more than 35 percent clay in some horizon in the lower part of the series control section. Galland, Gorin, and Keswick soils have more than 10 percent sand in the particle-size control section. Weller soils do not have an abrupt textural change.
GEOGRAPHIC SETTING: Marion soils are on narrow ridgetops of hills and treads of terraces. Slope gradients range from 0 to 5 percent. The soils formed in loess or loess and pedisediment. The mean annual temperature ranges from 54 to 57 degrees F, and mean annual precipitation ranges from 32 to 42 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Gorin and Keswick soils and the Hatton, Lindley and Winnegan soils. The somewhat poorly drained Gorin and the moderately well drained Keswick soils are on lower landscape positions. The moderately well drained Hatton soils do not have chroma of 2 or less in the upper 10 inches of the argillic horizon and are on similar positions or downslope. The well drained Lindley and the moderately well drained Winnegan soils have more than 10 percent sand in the particle-size control section and are downslope.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Runoff is low. Permeability is very slow. In undisturbed areas a perched water table is within 24 inches of the surface for some time during November to May in most years.
USE AND VEGETATION: The cleared areas are used to grow soybeans, small grain, corn, and grasses and legumes for hay or pasture. The remaining areas are in forest. The native vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: Central and northeast Missouri. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Marion County, Illinois, 1902.
REMARKS: Diagnostic horizons and features recognized in this series are: ochric epipedon - the zone from the surface of the soil to a depth of about 11 inches (A and E horizons); albic horizon - the zone from approximately 3 inches to 11 inches (E horizon); argillic horizon - the zone from approximately 11 inches to 52 inches (Bt1, Bt2, Btg1 and Btg2 horizons); Abrupt textural change- zone at about 11 inches; Vertic- linear extensibility of 6 cm or more within 100 cm; Aquic conditions- saturation and redox features at depths less than 24 inches.
The type location was moved to a more representative site within Boone County.
These soils are prime farmland.