LOCATION KNOBCREEK INEstablished Series
The Knobcreek series consists of very deep, well drained soils that formed in thin loess and the underlying clayey residuum, and are on hills and sinkholes underlain with limestone. Slope ranges from 6 to 25 percent. Mean annual precipitation is about 1092 mm (43 inches), and mean annual temperature is about 12 degrees C (54 degrees F).
TAXONOMIC CLASS: Fine-silty over clayey, mixed, active, mesic Typic Paleudalfs
TYPICAL PEDON: Knobcreek silt loam on a 13 percent slope in a pasture at an elevation of about 262 meters (860 feet) above MSL. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 cm (0 to 7 inches); brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; weak fine subangular blocky structure parting to moderate fine and medium granular; very friable; strongly acid; abrupt smooth boundary. (8 to 23 cm or 3 to 9 inches thick)
Bt1--18 to 28 cm (7 to 11 inches); strong brown (7.5YR 5/6) silty clay loam; moderate very fine and fine subangular blocky structure; friable; many distinct strong brown (7.5YR 4/6) clay films on faces of peds; 1 percent subangular gravel (chert); strongly acid; clear smooth boundary.
Bt2--28 to 41 cm (11 to 16 inches); strong brown (7.5YR 5/6) silty clay loam; moderate very fine and fine subangular blocky structure; friable; many distinct strong brown (7.5YR 4/6) clay films on faces of peds; 1 percent subangular gravel (chert); very strongly acid; clear wavy boundary. (Combined thickness of the Bt horizon is 13 to 33 cm or 5 to13 inches thick.)
2Bt3--41 to 79 cm (16 to 31 inches); 60 percent yellowish red (5YR 4/6) and 40 percent strong brown (7.5YR 5/6) clay; moderate very fine and fine angular blocky structure; firm; many prominent red (2.5YR 4/6) and common prominent dark yellowish brown (10YR 4/6) clay films on faces of peds; 1 percent subangular gravel (chert); very strongly acid; gradual wavy boundary.
2Bt4--79 to 109 cm (31 to 43 inches); strong brown (7.5YR 5/6) clay; moderate very fine and fine angular blocky structure; firm; common prominent red (2.5YR 4/6), few distinct strong brown (7.5YR 4/6) and few distinct pale brown (10YR 6/3) clay films on faces of peds; 1 percent subangular gravel (chert); very strongly acid; clear wavy boundary.
2Bt5--109 to 130 cm (43 to 51 inches); strong brown (7.5YR 5/6) clay; moderate very fine and fine angular blocky structure; firm; common prominent red (2.5YR 4/6), many faint strong brown (7.5YR 5/6) and very few prominent light gray (10YR 7/2) clay films on faces of peds; 1 percent subangular gravel (chert); very strongly acid; clear wavy boundary.
2Bt6--130 to 160 cm (51 to 63 inches); yellowish brown (10YR 5/6) clay; moderate very fine and fine angular blocky structure; firm; many prominent dark yellowish brown (10YR 4/6) and few prominent red (2.5YR 4/6) and few prominent light gray (10YR 7/2) clay films on faces of peds; 4 percent subangular gravel (chert) and 1 percent subrounded cobbles(chert); moderately acid; clear wavy boundary.
2Bt7--160 to 226 cm (63 to 89 inches); yellowish brown (10YR 5/6) clay; moderate very fine and fine angular blocky structure; firm; common prominent dark yellowish brown (10YR 4/6) and few prominent light gray (10YR 7/2) clay films on faces of peds; few prominent black (10YR 2/1) iron and manganese stains on faces of peds; 2 percent subangular gravel (chert); neutral. (Combined thickness of the 2Bt horizon is 102 to more than 254 cm or 40 to more than 100 inches.)
TYPE LOCATION: Floyd County, Indiana; 2050 feet west and 100 feet south of the northeast corner of sec. 36, T. 1 S., R. 4 E.; USGS Palmyra topographic quadrangle, lat. 38 degrees 23 minutes 19 seconds N., long. 86 degrees 01 minutes 17 seconds W., NAD 27; UTM Zone 16, 585467 easting and 4249393 northing, NAD 83.
RANGE IN CHARACTERISTICS:
Depth to the base of the argillic horizon and a lithic contact: 152 to more than 254 cm (60 to more than 100 inches)
Thickness of the loess: 20 to 51 cm (8 to 20 inches)
Rock fragments: dominantly gravel (chert), and includes cobbles to boulders in the 2Bt horizon
Mean Annual Soil Temperature (MAST) range: 12 to 15 degrees C (53 to 59 degrees F)
Ap horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5
Chroma: 3 to 6
Texture: silt loam or silty clay loam
Clay content: 15 to 35 percent
Sand content: 2 to 12 percent
Rock fragment content: 0 to 14 percent
Reaction: very strongly acid to neutral
A horizon, 5 to 10 cm (2 to 4 inches) thick, where present:
Hue: 10YR
Value: 2 or 3
Chroma: 1 to 3
Texture: silt loam
Clay content: 13 to 20 percent
Sand content: 2 to 12 percent
Rock fragment content: 0 to 14 percent
Reaction: very strongly acid or strongly acid
E or BE horizon, where present:
Hue: 10YR
Value: 5 or 6
Chroma: 3 or 4
Texture: silt loam
Reaction: very strongly acid or strongly acid, and the upper part ranges to neutral in limed areas
Bt horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5
Chroma: 6 to 8
Texture: silt loam or silty clay loam
Clay content: 24 to 38 percent
Sand content: 2 to 10 percent
Reaction: very strongly acid, and the upper part ranges to neutral in limed areas
Rock fragment content: 0 to 14 percent gravel
2Bt horizon:
Hue: 2.5YR to 7.5YR, and ranges to 10YR in the lower part
Value: 4 or 5
Chroma: 6 to 8, and typically variegated
Texture: silty clay or clay, or their gravelly analogues
Clay content 45 to 73 percent
Sand content: 2 to 20 percent
Reaction: very strongly acid or strongly acid in the upper part, and ranges to neutral in the lower part
Rock fragment content: 0 to 20 percent gravel and 0 to 10 percent cobbles, stones and boulders
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Knobcreek soils are on shoulders and back slopes of hills and sinkholes underlain with limestone of Mississippian Age. Slopes are typically 6 to 22 percent, but range to 25 percent. The soils formed in 20 to 51 cm (8 to 20 inches) of loess, and the underlying clayey residuum. The mean annual temperature ranges from 11 to 14 degrees C (52 to 57 degrees F), and the mean annual precipitation ranges from 1016 to 1168 mm (40 to 46 inches). Frost free days range from 170 to 200, and elevation ranges from 152 to 305 meters (500 to 1000 feet).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caneyville, Crider, Haggatt, and Navilleton soils which are all underlain with limestone. The moderately deep Caneyville, and deep Haggatt soils are on shoulders and back slopes. The well drained, very deep, more silty Crider and Navilleton soils are on summits, shoulders, and back slopes.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers/s) in the upper part of the subsoil and moderately low to moderately high (0.42 to 4.23 micrometers/s) in the lower part. Permeability is moderate in the upper part of the subsoil and moderately slow or slow in the lower part. The potential for surface water runoff is high or very high.
USE AND VEGETATION: Most of these soils are used to grow grasses and legumes for hay and pasture or are in woodland. Some areas with slopes of less than 18 percent are used to grow corn, soybeans and small grain. Native vegetation is deciduous hardwood forest.
DISTRIBUTION AND EXTENT: South-central Indiana. The soil is of small extent in MLRA 122.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Floyd County, Indiana 1999.
REMARKS: Base saturation data for this series as of 9/99 shows pedons to be both above and below 35 percent at the critical depth. This series is tentatively placed in the Alfisol Order. Also data shows that the particle-size control section is both contrasting and non-contrasting, but dominantly contrasting.
Representative component and horizon data is in DMU# 151472.
Diagnostic horizons and features recognized in this pedon are: 1) Ochric epipedon - the zone between 0 and 18 cm (0 and 7 inches) (Ap horizon); 2) Argillic horizon - the zone between 18 and 226 cm (7 and 89 inches) (Bt and 2Bt horizons).
ADDITIONAL DATA: Laboratory data on sample number 97IN043-004 is from the NSSL in Lincoln, NE.