LOCATION WHITCOMB INEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Aeric Paleaquults
TYPICAL PEDON: Whitcomb silt loam on a 1 percent slope in a pasture field at an elevation of about 174 meters (570 feet) above MSL. (Colors are for moist soil unless otherwise stated.)
A--0 to 5 cm (0 to 2 inches); brown (10YR 4/3) silt loam, very pale brown (10YR 7/3) dry; moderate fine granular structure; friable; many very fine and fine roots; moderately acid; abrupt smooth boundary. (0 to 10 cm or 0 to 4 inches thick)
Ap--5 to 23 cm (2 to 9 inches); brown (10YR 5/3) silt loam, very pale brown (10YR 7/3) dry; moderate medium granular structure; friable; common very fine and fine roots; common fine faint light yellowish brown (10YR 6/4) masses of iron accumulation in the matrix; common medium irregular iron and manganese concretions; 1 percent gravel; moderately acid; abrupt smooth boundary. (18 to 30 cm or 7 to 12 inches thick)
BE--23 to 38 cm (9 to 15 inches); light yellowish brown (10YR 6/4) silt loam; weak fine subangular blocky structure; friable; common very fine roots; common fine prominent brownish yellow (10YR 6/8) masses of iron accumulation in the matrix; common fine irregular iron and manganese concretions; common medium distinct light gray (10YR 7/2) iron depletions in the matrix; 1 percent gravel; extremely acid; clear wavy boundary. (10 to 20 cm or 4 to 8 inches thick)
Btg1--38 to 56 cm (15 to 22 inches); light brownish gray (10YR 6/2) silty clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; few very fine roots between peds; many distinct light brownish gray (10YR 6/2) clay films on faces of peds; many medium distinct light yellowish brown (10YR 6/4) and common medium prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; few fine irregular iron and manganese concretions; 1 percent gravel; extremely acid; clear wavy boundary.
Btg2--56 to 76 cm (22 to 30 inches); light brownish gray (10YR 6/2) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; few very fine roots between peds; many distinct gray (10YR 6/1) clay films on faces of peds; many medium prominent strong brown (7.5YR 5/8) and common distinct light yellowish brown (10YR 6/4) masses of iron accumulation in the matrix; common medium irregular iron and manganese oxide concretions; 1 percent gravel; extremely acid; gradual wavy boundary. (Combined thickness of the Bt horizon is 30 to 46 cm or 12 to 18 inches.)
2Btgx1--76 to 94 cm (30 to 37 inches); gray (10YR 6/1) silty clay loam; moderate coarse prismatic structure parting to moderate coarse subangular blocky; firm; many distinct gray (10YR 6/1) and (10YR 5/1) clay films on faces of peds; few prominent very dark gray (N 3/) manganese stains on faces of peds and in pores; many medium prominent strong brown (7.5YR 5/8) and few distinct light yellowish brown (10YR 6/4) masses of iron accumulation in the matrix; 2 percent gravel; 40 percent brittle; extremely acid; clear wavy boundary.
2Btgx2--94 to 122 cm (37 to 48 inches); gray (10YR 6/1) silty clay loam; weak coarse prismatic structure parting to moderate coarse subangular blocky; firm; common prominent gray (10YR 5/1) clay films on faces of peds; few prominent very dark gray (N 3/) manganese stains on faces of peds and in pores; many coarse prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; 2 percent gravel; 50 percent brittle; extremely acid; gradual wavy boundary. (Combined thickness of the 2Btgx horizon is 41 to 51 cm or 16 to 20 inches.)
3Btg--122 to 142 cm (48 to 56 inches); gray (10YR 6/1) silty clay; weak medium subangular blocky structure; firm; few prominent gray (10YR 5/1) clay films on faces of peds; many coarse prominent strong brown (7.5YR 5/8) masses of iron accumulation in the matrix; 2 percent gravel; extremely acid; clear wavy boundary. (15 to 25 cm or 6 to 10 inches thick)
3BCg--142 to 155 cm (56 to 61 inches); 60 percent light brownish gray (10YR 6/2) and 30 percent pinkish gray (7.5YR 6/2) very parachannery silty clay loam; moderate thick platy structure; firm; many medium distinct brown (7.5YR 4/4) and few fine prominent strong brown (7.5YR 5/8) masses of iron accumulation in the matrix; 40 percent parachanners (shale); extremely acid; abrupt wavy boundary. (10 to 25 cm or 4 to 10 inches thick)
3R--155 to 203 cm (61 to 80 inches); very dark gray (10YR 3/1) very strongly cemented, fissile shale.
TYPE LOCATION: Scott County, Indiana; about 3/4 mile northeast of Austin; 210 feet east and 180 feet south of the center of sec. 30, T. 4 N., R. 7 E.; USGS Crothersville, Indiana topographic quadrangle; lat. 38 degrees 45 minutes 26 seconds N. and long. 085 degrees 47 minutes 06 seconds W., NAD 27; UTM Zone 16, 605571 easting and 42905442 northing, NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the loess: 61 to 102 cm or 24 to 40 inches
Depth to the base of the argillic horizon: 122 to 165 cm or 48 to 65 inches
Depth to a layer with fragic soil properties: 61 to 91 cm or 24 to 36 inches
Depth to bedrock (lithic contact): 152 to 203 cm or 60 to 80 inches
Particle-size control section: averages 24 to 34 percent clay and 4 to 12 percent sand
Rock fragments: in Btg and 2Btgx are dominantly of igneous lithology
Ap horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 3 or 4
Texture: silt loam
Clay content: 12 to 24 percent
Sand content: 4 to 12 percent
Reaction: very strongly acid to neutral
A horizon (0 to 10 cm or 0 to 4 inches thick):
Hue: 10YR
Value: 3 or 4
Chroma: 3 or 4
Texture: silt loam
Clay content: 12 to 24 percent
Sand content: 4 to 12 percent
Reaction: very strongly acid or strongly acid
BE horizon:
Hue: 10YR
Value: 6
Chroma: 3 to 6
Texture: silt loam
Clay content: 20 to 26 percent
Sand content: 4 to 12 percent
Reaction: extremely acid or very strongly acid
Btg horizon:
Hue: 10YR
Value: 6 or 7
Chroma: 1 or 2
Texture: silt loam or silty clay loam
Clay content: 24 to 32 percent
Sand content: 4 to 12 percent
Reaction: extremely acid or very strongly acid
2Btgx horizon:
Hue: 10YR
Value: 5 to 7
Chroma: 1 or 2
Texture: silty clay loam
Clay content: 27 to 35 percent
Sand content: 5 to 12 percent
Reaction: extremely acid or very strongly acid
Rock fragment content: 1 to 3 percent gravel
Percent brittleness: 30 to 60
3Btg horizon:
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 1 or 2
Texture: silty clay loam or silty clay
Clay content: 35 to 50 percent
Sand content: 5 to 10 percent
Reaction: extremely acid or very strongly acid
Rock fragment content: 0 to 3 percent gravel
3BCg or 3CBg horizon:
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 1 or 2
Texture: parachannery to extremely parachannery analogues silty clay loam or silty clay
Clay content: 35 to 45 percent
Sand content: 5 to 10 percent
Reaction: extremely acid or very strongly acid
Pararock fragment content: 15 to 60 parachanners
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Whitcomb soils are on strath terraces adjacent to till plains considered to be of the Illinoian stage. They formed in loess, silty slope alluvium, and the underlying residuum from black shale. In Indiana, the shale is from the New Albany formation, Devonian System. Mean annual temperature ranges from 11 to 14 degrees C (52 to 57 degrees F) and the mean annual precipitation ranges from 1016 to 1143 mm (40 to 45 inches). Frost-free days range from 170 to 200.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Deputy, Jennings, Scottsburg and Trappist soils. The moderately well drained Deputy and Jennings soils are on backslopes of higher lying till plains. The moderately well drained Scottsburg soils are on summits and shoulders of strath terraces. The well drained, moderately deep Trappist soils are on lower lying backslopes.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/s) above the horizon with fragic soil properties and low to moderately high (0.07 to 1.41 micrometers/s) in and below this horizon. Permeability is moderate above the horizon with fragic soil properties and slow or very slow in and below this horizon. The potential for surface water runoff is medium. In undrained areas, the depth to an intermittent perched high water table is at 0.1 to 0.5 meters (0.5 to 1.5 feet) from December through April in normal years. In drained areas, the depth to an intermittent perched high water table is at 0.1 to 0.6 meters (0.5 to 2.0 feet) from December through April in normal years.
USE AND VEGETATION: Most areas are being used for growing cultivated crops and hay and pasture. A few areas are used for woodland. Native vegetation is mixed hardwood forest.
DISTRIBUTION AND EXTENT: Southeastern Indiana. The acreage is of small extent in MLRA 114A in Indiana.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Scott County, Indiana, 1995.
REMARKS: The Whitcomb series was made inactive in 1972. It is reactivated and the concept updated with this description. The basic concept remains the same as was in 1972.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 23 cm or 0 to 9 inches (A and Ap horizons)
Argillic horizon: 38 to 142 cm or 15 to 56 inches (Btg1, Btg2, 2Btgx1, 2Btgx2, 3Btg horizons)
Fragic Soil Properties: 76 to 122 cm or 30 to 48 inches (2Btgx1 and 2Btgx2 horizons)
Redoximorphic features: at 23 to 155 cm or 9 to 61 inches
Lithic contact: at 155 to 203 cm or 61 to 80 inches
The clay films with a chroma of 2 or less are iron depleted redoximorphic features.
ADDITIONAL DATA: Lab data available for the typical pedon, S89IN-143-14 is at the National Soil Survey Lab, Lincoln, NE.