LOCATION BELKNAP IL+IN KY MOEstablished Series
The Belknap series consists of very deep, somewhat poorly drained soils formed in acid, silty alluvium on flood plains. Permeability is moderate or moderately slow. Slopes range from 0 to 4 percent, but are dominantly 2 percent or less. Mean annual precipitation is about 43 inches and mean annual temperature is about 56 degrees F.
TAXONOMIC CLASS: Coarse-silty, mixed, active, acid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Belknap silt loam - in a cultivated field on a nearly level flood plain. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine and medium granular structure; friable; strongly acid; abrupt smooth boundary. (6 to 10 inches thick)
A--7 to 13 inches; dark grayish brown (10YR 4/2) silt loam; weak thin platy structure parting to weak fine granular; friable; slightly compact as a plow pan; few medium faint brown (10YR 5/3) and few fine prominent yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; strongly acid; gradual smooth boundary. (0 to 10 inches thick)
Bg--13 to 27 inches; dark grayish brown (10YR 4/2), grayish brown (10YR 5/2), and brown (10YR 5/3) silt loam; weak medium granular structure with a tendency toward subangular blocky; friable; few medium faint light brownish gray (10YR 6/2) iron depletions and common fine distinct yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few iron and manganese concretions; strongly acid; gradual smooth boundary. (6 to 40 inches)
Cg1--27 to 59 inches; light brownish gray (10YR 6/2) silt loam; massive; friable; common fine prominent dark reddish brown (2.5YR 3/4) and yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; many iron and manganese concretions increasing in number and size as depth increases; strongly acid; gradual smooth boundary.
Cg2--59 to 65 inches; dark gray (10YR 4/1) silt loam; massive; friable; common medium faint gray (10YR 6/1) iron depletions and few medium prominent brown (7.5YR 5/4) masses of iron accumulation in the matrix; many iron and manganese concretions; moderately acid.
TYPE LOCATION: Wabash County, Illinois; about 10 miles north of Mt. Carmel; 350 feet north of the center of the road on the west side of the stream; 1,000 feet east and 1,000 feet north of the center of sec. 33, T. 2 N., R. 12 W.; USGS St. Francisville, IL. topographic quadrangle; lat. 38 degrees 33 minutes 52 seconds N. and long. 087 degrees 44 minutes 50.5 seconds W.
RANGE IN CHARACTERISTICS: The particle-size control section averages less than 18 percent clay and is strongly acid or very strongly acid. Depth to the base of soil development typically ranges from 12 to 40 inches, but may be as deep as 60 inches in some pedons.
The Ap and/or A horizon has hue of 10YR, value of 4 to 6 (6 or 7 dry), and chroma of 2 or 3. Some pedons in uncultivated areas have surface value of 3 less than 7 inches thick. Texture is silt loam or silt. The A horizon has weak or moderate, fine or medium, granular or thin platy structure. Reaction is very strongly acid to moderately acid, unless limed.
The Bg or Bw horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 4. Redox features have hue of 2.5YR, 5YR, 7.5YR, 10YR, or 2.5Y, value of 3 to 7, and chroma of 1 to 8. Texture is silt loam or silt to a depth of at least 40 inches. Some pedons contain strata of loam or silty clay loam at depths below 40 inches.
The Cg or C horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 1 to 4. Light gray (10YR 7/1 or 7/2) silt pockets are common. Redox features have hue of 2.5YR, 5YR, 7.5YR, 10YR, or 2.5Y, value of 3 to 7, and chroma of 1 to 8. Texture is silt loam or silt to a depth of at least 40 inches. Some pedons contain strata of loam or silty clay loam at depths below 40 inches.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Belknap soils are on nearly level to gently undulating flood plains. Slope gradients range from 0 to 4 percent, but are dominantly 2 percent or less. They formed in silty, acid alluvium. Mean annual air temperature ranges from 52 to 58 degrees F, mean annual precipitation ranges from 38 to 48 inches, frost free days ranges from 170 to 200 days, and elevation ranges from 340 feet to 700 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Sharon and Bonnie soils. Belknap soils are the somewhat poorly drained member of a drainage sequence that includes moderately well drained Sharon soils and the poorly drained Bonnie soils. Sharon soils are on slightly higher parts of the flood plain or are on natural levees. Bonnie soils are on lower-lying parts of the flood plain.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Permeability is moderate or moderately slow. Flooding from stream overflow is common during winter and spring and after summer storms of heavy rainfall. The potential for surface water runoff is negligible or very low. This soil has an apparent water table at a depth of 0.5 to 2 feet at some time between December and April in normal years.
USE AND VEGETATION: Most areas are cultivated. Corn and soybeans are the principal crops. Native vegetation is hardwood trees.
DISTRIBUTION AND EXTENT: Southern Illinois, Southern Indiana, Missouri, and Kentucky in MLRA's 113, 114, 115, 116 and 120. The series is of large extent (about 270,000 acres correlated).
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Johnson County, Illinois, 1942.
REMARKS:This soil is being reclassified (4/2000) as an inceptisol based on the original concept of the series and the presence of a cambic horizon in the majority of pedons. In many areas, this soil has been mapped both with and without a cambic horizon and during MLRA updating these soils will be evaluated to determine if another series in the order entisols should be established.
Diagnostic horizons recognized in this pedon are: Ochric epipedon - the zone from the surface to a depth of 13 inches (Ap and A horizons); Cambic horizon - the zone from 13 to 27 inches (Bg horizon).