LOCATION RUARK ILEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Typic Endoaqualfs
TYPICAL PEDON: Ruark fine sandy loam - on a nearly level terrace in a cultivated field on a terrace at an elevation of about 334 feet above MSL. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; grayish brown (10YR 5/2) fine sandy loam, light gray (10YR 7/2) dry; weak medium granular structure; friable; common fine distinct yellowish brown (10YR 5/4) masses of iron-manganese accumulation in the matrix; strongly acid; abrupt smooth boundary. (6 to 9 inches thick)
Eg--7 to 18 inches; grayish brown (10YR 5/2) fine sandy loam; weak thick platy structure; friable; common medium prominent brownish yellow (10YR 6/6) masses of iron accumulation in the matrix; very strongly acid; clear smooth boundary. (8 to 13 inches thick)
BEg--18 to 20 inches; gray (10YR 5/1) loam; weak coarse subangular blocky structure; friable; few fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; very strongly acid; clear smooth boundary. (2 to 5 inches thick)
Btg1--20 to 33 inches; gray (10YR 5/1) clay loam; weak medium prismatic structure parting to moderate coarse subangular blocky; friable; common faint dark grayish brown (10YR 4/2) clay films on faces of peds; common medium faint light gray (10YR 7/2) iron depletions and common fine and medium prominent brownish yellow (10YR 6/6) and yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; very strongly acid; gradual smooth boundary.
Btg2--33 to 37 inches; light gray (10YR 6/1) sandy clay loam; weak coarse subangular blocky structure; friable; few faint grayish brown (10YR 5/2) clay films on faces of peds; common medium prominent yellowish brown (10YR 5/6 and 5/8) masses of iron in the matrix; strongly acid; clear smooth boundary. (Combined thickness of the Btg horizons is 12 to 24 inches.)
Cg1--37 to 44 inches; light gray (10YR 6/1) loam; massive; friable; common fine prominent yellowish brown (10YR 5/6 and 5/8) masses of iron accumulation in the matrix; common fine and medium concretions and stains (iron and manganese oxides); slightly acid; clear smooth boundary. (0 to 15 inches thick)
Cg2--44 to 60 inches; light brownish gray (10YR 6/2) fine sandy loam; massive; friable; common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; neutral.
TYPE LOCATION: Alexander County, Illinois; about 3/4 mile south of Sandusky; 1195 feet north and 840 feet west of the southeast corner, sec. 24, T. 15 S., R. 2 W. U.S.G.S. Tamms, IL topographic quadrangle; Latitude XX degrees, XX minutes, XX seconds North and Longitude XX degrees, XX minutes, XX seconds West. NAD 27.
RANGE IN CHARACTERISTICS: The solum commonly is 35 to 40 inches thick and ranges from 30 to 50 inches. The solum is moderately acid to very strongly acid, except surface layers that have been limed range to include neutral. The particle size control section averages between 20 and 35 percent clay and more than 30 percent fine sand or coarser.
The A or Ap horizon has hue of 10YR, value of 3 to 5 (6 or 7 dry), and chroma of 1 or 2. It commonly is fine sandy loam but is loam or very fine sandy loam in some pedons. Redoximorphic accumulations are present. Organic carbon content averages less than 0.6 percent.
The E horizon has hue of 10YR or 2.5Y, value of 5 to 7, and chroma of 2 or less. Redoximorphic features are present. It is loam, sandy loam, or fine sandy loam.
The BE horizon has hue of 10YR, 2.5Y, or 5Y; value 4 to 6; and chroma of 2 or less. Redoximorphic features are present. It is loam, sandy loam, or fine sandy loam.
The Btg horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 2 or less. It commonly has redoximorphic features with brown, yellowish brown, or gray colors. It is sandy clay loam, clay loam, loam, or sandy loam.
The Cg horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 2 or less. It commonly is gray with yellowish brown redoximorphic features. It is fine sandy loam to sandy clay loam and commonly contains thin strata of loamy sand, sand, fine gravel, loam, silt loam, or silty clay loam. It is moderately acid to slightly alkaline.
COMPETING SERIES: These are the Cosmos and Damascus series. Cosmos soils have an average precipitation of 55 inches and less variation between summer and winter average air temperature. Damascus soils average more than 5 percent rock fragments in the Btg horizon and more than 15 percent rock fragments in the Cg horizon.
GEOGRAPHIC SETTING: Ruark soils commonly are on outwash plains and alluvial or eolian terraces, and less commonly in depressions on uplands. The slope gradient is 0 to 2 percent. Ruark soils formed in loamy material. Mean annual air temperature ranges from 50 to 57 degrees F., and the mean annual precipitation ranges from 35 to 48 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alvin, Orio, and Roby soils. Alvin and Roby soils are higher on the landscape and have less than 18 percent clay in the argillic horizon. The Orio soils have a dark surface that meets the mollic subgroup level of taxonomy and are on similar landscape positions.
DRAINAGE AND PERMEABILITY: Poorly drained. The potential for surface water runoff is negligible to medium. Permeability is moderate or moderately slow in the argillic horizon and moderately rapid to moderately slow in the substratum.
USE AND VEGETATION: Most areas of Ruark soils are cultivated. Corn, soybeans, small grain, and meadow are the principal crops. Native vegetation is deciduous hardwoods, mainly oak and hickory.
DISTRIBUTION AND EXTENT: Illinois. Extent is small.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Lawrence County, Illinois, 1952.
REMARKS: Diagnostic horizons and Features in this pedon are:
Ochric epipedon: from the surface to a depth of 20 inches (Ap, Eg, Beg horizons);
Argillic horizon: from 20 to 37 inches (Btg1 and Btg2 horizons);
Endosaturation; less than 2 chroma matrix and redox features in all horizons of the series control section;