LOCATION ROBY IL+IN WIEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Aquic Hapludalfs
TYPICAL PEDON: Roby fine sandy loam - in a nearly level cultivated field at an elevation of about 166 meters (543 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 15 cm (0 to 6 inches); dark grayish brown (10YR 4/2) fine sandy loam, light brownish gray (10YR 6/2) dry; weak medium granular structure; very friable; moderately acid; abrupt smooth boundary. [15 to 25 cm (6 to 10 inches) thick]
E--15 to 25 cm (6 to 10 inches); pale brown (10YR 6/3) loamy fine sand; weak medium platy structure; very friable; many dark grayish brown (10YR 4/2) coatings on faces of peds; few medium and fine distinct very dark gray (10YR 3/1) iron-manganese oxide accumulations on faces of peds; moderately acid; abrupt smooth boundary. [10 to 30 cm (4 to 12 inches) thick]
BE--25 to 38 cm (10 to 15 inches); pale brown (10YR 6/3) loamy fine sand; weak medium subangular blocky structure; very friable; common fine distinct yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; moderately acid; clear smooth boundary. [0 to 15 cm (0 to 6 inches) thick]
Btg1--38 to 64 cm (15 to 25 inches); light brownish gray (10YR 6/2) fine sandy loam; weak medium subangular blocky structure; very friable; few faint grayish brown (10YR 5/2) clay films on faces of peds; many fine and medium yellowish red (5YR 4/6) weakly cemented iron-manganese oxide nodules throughout in the lower 4 inches; common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; moderately acid; abrupt smooth boundary.
Btg2--64 to 81 cm (25 to 32 inches); light brownish gray (10YR 6/2) fine sandy loam; weak medium subangular blocky structure; very friable; few faint grayish brown (10YR 5/2) clay films on faces of peds and as coatings on sand grains; common fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; moderately acid; clear smooth boundary. [Combined thickness of the Btg horizon is 33 to 76 cm (13 to 30 inches).]
Cg--81 to 152 cm (32 to 60 inches); stratified light brownish gray (10YR 6/2) loamy fine sand and yellowish brown (10YR 5/8) and strong brown (7.5YR 5/6) fine sandy loam; single grain and massive; loose and very friable; few fine dark brown (7.5YR 3/2) very weakly cemented iron-manganese oxide nodules throughout; moderately acid.
TYPE LOCATION: Grundy County, Illinois; about 4.8 kilometers (3 miles) west and 1.6 kilometers (1 mile) north of Carbon Hill; 634 meters (2,079 feet) east and 351 meters (1,152 feet) south of the northwest corner of sec. 30, T. 33 N., R. 8 E.; USGS Coal City, Illinois topographic quadrangle; lat. 41 degrees 18 minutes 44 seconds N. and long. 88 degrees 21 minutes 18 seconds W., NAD 27; UTM Zone 16, 386575 easting and 4574307 northing, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of soil development commonly is 76 to 122 cm (30 to 48 inches), but ranges to 152 cm (60 inches). The particle-size control section ranges from 12 to 18 percent clay and 45 to 80 percent sand.
The Ap horizon has hue of 10YR, value of 4 or 5, and chroma of 2 or 3. Some pedons have an A horizon 1 to 5 inches in thickness that has hue of 10YR, value of 3 or 4, and chroma of 1 or 2. The A or Ap horizon commonly is fine sandy loam or loam, but some pedons are loamy fine sand or sandy loam. Reaction ranges from very strongly acid to slightly alkaline.
The E horizon has hue of 10YR, value of 4 to 6, and chroma of 3 or 4. It is loamy fine sand or fine sandy loam. Reaction ranges from very strongly acid to moderately acid.
The Bt or Btg horizon has hue of 10YR, value of 4 to 6, and chroma of 2 to 6. Texture is fine sandy loam, sandy loam, or loam. It averages between 12 and 18 percent clay and between 45 and 80 percent sand. Thin layers, less than 25 cm (10 inches) thick, of clay loam or sandy clay loam are in some pedons. Reaction ranges from very strongly acid to moderately acid.
Some pedons have a BC or BCg horizon.
The C or Cg horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 2 to 8. It commonly contains iron-manganese oxide concretions or nodules. Texture is stratified sand to loam, and some pedons contain a component of gravel or thin strata of gravel. Gravel content averages less than 10 percent. Reaction ranges from moderately acid to slightly alkaline, and some pedons contain carbonates.
COMPETING SERIES: Roby is the only series in this family. Soils in similar families are the Bronson, Harbor, Ridgeville, and Whitaker series. Bronson soils contain more than 10 percent gravel in the lower part of the series control section. Harbor soils average less than 52 percent sand in the lower part of the series control section. Ridgeville soils have a mollic epipedon. Whitaker soils average more than 18 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: Roby soils are on outwash plains, stream terraces, and foot slopes in the uplands. The soils formed in stratified water-laid sediments. Slope gradients range from 0 to 7 percent. Mean annual precipitation ranges from 810 to 1020 mm (32 to 48 inches), mean annual air temperature ranges from 8 to 14 degrees C (48 to 57 degrees F), and elevation ranges from 104 to 305 meters (340 to 1000 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Ridgeville soils and the Alvin, Darroch, Hoopeston, Martinsville, Ruark, and Selma soils. Ridgeville soils are on similar landscapes. Alvin soils are well drained and are on slightly higher topography. Darroch soils are on nearly level lake plains and have a mollic epipedon and a higher percentage of clay in the particle-size control section. Hoopeston soils are on similar landscapes but have a mollic epipedon and do not have an argillic horizon. Martinsville soils are on similar landscapes and are well drained and have a higher percentage of clay in the particle-size control section. Ruark soils are poorly drained, are nearly level, and are on lower topography. Selma soils are in broad depressions, are poorly drained, have mollic epipedons, and have a higher percentage of clay in the particle-size control section.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. The potential for surface runoff ranges from negligible to low. Saturated hydraulic conductivity is high (14.11 to 42.33 micrometers per second). Permeability is moderately rapid.
USE AND VEGETATION: Most areas are cultivated. Corn, soybeans, small grain, and meadow are the principal crops. Some areas are wooded. Natural vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: Illinois, Indiana, and Wisconsin. The soils are of moderate extent in MLRAs 110, 113, 114B, 115A, 115B, and 120A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana.
SERIES ESTABLISHED: Christian County, Illinois, 1947.
REMARKS: Diagnostic horizons and features in this pedon are: ochric epipedon - the zone from 0 to 38 cm (0 to 15 inches) (Ap, E, and BE horizons); albic horizon - the zone from 15 to 25 cm (6 to 10 inches) (E horizon); argillic horizon - the zone from 38 to 81 cm (15 to 32 inches) (Btg1 and Btg2 horizons); udic moisture regime; mesic temperature regime.