LOCATION FISHHOOK ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Hapludalfs
TYPICAL PEDON: Fishhook silt loam - on an east-facing slope of 8 percent in a cultivated field at an elevation of about 725 feet (221 meters) above mean sea level (MSL). (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches (0 to 15 cm); dark yellowish brown (10YR 4/4) silt loam, light yellowish brown (10YR 6/4), dry; moderate medium subangular blocky structure; friable; few very fine and fine roots throughout; many fine continuous tubular pores; few fine prominent irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; moderately acid; abrupt smooth boundary. [5 to 10 inches ( 12 to 25 cm) thick]
Bt1--6 to 17 inches (15 to 43 cm); yellowish brown (10YR 5/4) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; few fine roots throughout; many fine continuous tubular pores; few distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; few fine prominent irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; common medium distinct irregular yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common medium distinct irregular light brownish gray (10YR 6/2) iron depletions in the matrix; strongly acid; clear wavy boundary.
Bt2--17 to 22 inches (43 to 56 cm); yellowish brown (10YR 5/4) silt clay loam; moderate medium subangular blocky structure; friable; few fine roots throughout; few fine continuous tubular pores; few distinct brown (10YR 4/3) clay films lining root channels and pores; common fine prominent irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; common medium distinct irregular yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common medium distinct irregular light brownish gray (10YR 6/2) iron depletions in the matrix; strongly acid; clear wavy boundary.
Bt3--22 to 27 inches (56 to 69 cm); yellowish brown (10YR 5/4) silty clay loam; moderate fine prismatic structure parting to moderate medium subangular blocky; friable; few very fine roots throughout; few very fine continuous tubular pores; common distinct dark yellowish brown (10YR 4/4) and few distinct brown (10YR 5/3) clay films on faces of peds; few fine prominent irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; common fine distinct irregular yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few fine distinct irregular light brownish gray (10YR 6/2) iron depletions along faces of peds; strongly acid; clear wavy boundary. [Combined thickness of the Bt horizon is 10 to 30 inches (25 to 76 cm).]
2Bt4--27 to 35 inches (69 to 89 cm); yellowish brown (10YR 5/4) silty clay loam; moderate fine subangular blocky structure; friable; few distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; few fine prominent irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; few fine distinct irregular light brownish gray (10YR 6/2) iron depletions in the matrix; few fine rock fragments; strongly acid; clear wavy boundary.
2Bt5--35 to 46 inches (89 to 117 cm); yellowish brown (10YR 5/4) silty clay loam; moderate medium subangular blocky structure; friable; few distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; few prominent light gray (10YR 7/2) silt coatings on faces of peds; few fine prominent irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; few fine distinct irregular light brownish gray (10YR 6/2) iron depletions in the matrix; few very fine and fine rock fragments; moderately acid; clear wavy boundary.
2Bt6--46 to 58 inches (117 to 147 cm); yellowish brown (10YR 5/4) clay loam; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; firm; common distinct dark yellowish brown (10YR 4/4) clay films on faces of peds; few fine and medium prominent rounded black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; common fine distinct irregular yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common fine and medium distinct irregular light brownish gray (10YR 6/2) iron depletions in the matrix; few fine and medium rock fragments; slightly acid; clear wavy boundary.
2Bt7--58 to 68 inches (147 to 172 cm); brown (10YR 5/3) clay loam; moderate medium prismatic structure parting to moderate fine subangular blocky; firm; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds; common fine distinct irregular black (2.5Y 2/1) masses of iron-manganese oxide accumulation throughout; common medium distinct irregular yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common fine faint irregular light brownish gray (10YR 6/2) iron depletions in the matrix; few very fine and fine rock fragments; slightly acid; gradual wavy boundary.
2Btg--68 to 82 inches (172 to 208 cm); grayish brown (10YR 5/2) clay; moderate medium prismatic structure parting to moderate fine subangular blocky; firm; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds; common medium prominent irregular black (2.5Y 2/1) iron-manganese oxide concretions throughout; common fine and medium prominent irregular yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; few very fine and fine rock fragments; slightly acid. [Combined thickness of the 2Bt and/or 2Btg horizons is 30 to more than 72 inches (76 to more than 183 cm).]
TYPE LOCATION: Brown County, Illinois; about 5 miles west and 3 miles north of Mt. Sterling, IL; 1,800 feet south and 360 feet east of the NW corner of sec. 34, T. 1 N., R. 4 W.; U.S.G.S. Mt. Sterling, IL topographic quadrangle; lat. 40 degrees, 1 minute, 36.2 seconds N. and long. 91 degrees, 6 minutes, 18.4 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon is greater than 50 inches. Loess thickness ranges from 20 to 40 inches (51 to 102 cm). The particle-size control section averages between 27 and 35 percent clay. Rock fragments are absent in the loess and range from 1 to 15 percent in the till. Rock fragments are of mixed lithology with very low content of shale and siltstone.
The Ap or A horizon has hue of 10YR, value of 3 to 5, and chroma typically of 2 or 3 but includes chroma of 4 in eroded pedons that have subsoil material mixed into the Ap horizon. It is silt loam or silty clay loam. Reaction is strongly acid to neutral.
An E horizon is present where it has not been mixed into the Ap horizon. A BE horizon is present in some pedons.
The Bt or Btg horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 3 or 4 in the upper part and 1 to 4 in the lower part. Redoxmorphic features have a hue of 10YR, 2.5Y or 7.5YR, value of 2 to 6, and chroma of 1 to 6. Texture is silty clay loam and averages between 27 to 35 percent clay. Average sand content is less than 10 percent. Reaction is very strongly acid to neutral.
The 2Bt or 2Btg horizon has hue of 10YR, 2.5Y, or 5Y; value of 2 to 7; and chroma of 1 to 4. Redoxmorphic features have a hue of 10YR, 2.5Y or 7.5YR, value of 2 to 6, and chroma of 1 to 6. Texture is clay loam, clay, silty clay, silty clay loam, or loam, and averages between 35 and 45 percent clay. Average sand content ranges from 10 to 35 percent. Reaction is neutral to very strongly acid in the upper part and moderately acid to slightly alkaline in the lower part.
Some pedons have a 2BC or 2BCg horizon.
Where present, the 2BC, 2BCg or 2Cg horizon has hue of 10YR, 2.5Y, or 5Y; value of 4 to 6; and chroma of 1 or 2. Redoxmorphic features have a hue of 10YR, 2.5Y or 7.5YR, value of 2 to 6, chroma of 1 to 6. It is clay loam, clay, silty clay loam, or loam. Reaction is slightly acid to moderately alkaline.
COMPETING SERIES: These are the Appleriver, Blair, Bunkum, Freeburg, Geff, Glenford, Keene, Muren, Reesville, Sugarvalley, Torox, and Xenia series. Appleriver soils have a paralithic contact within a depth of 60 inches. Blair soils average more than 10 percent sand within a depth of 20 inches. Bunkum, Freeburg, Geff, Glenford, Muren, Reesville, Sugarvalley, Torox and Xenia soils average less than 35 percent clay in the lower part of the series control section. In addition, Reesville and Torox soils contain carbonates within a depth of 60 inches. Keene soils have rock fragments in the lower part of the series control section that are mostly shale and siltstone.
GEOGRAPHIC SETTING: Fishhook soils are on gently sloping to moderately steep parts of dissected Illinoian and Pre-Illinoian till plains. Slope gradients are 2 to 18 percent. These soils formed in 20 to 40 inches (51 to 102 cm) of loess and the underlying till that contains a strongly developed paleosol. Mean annual temperature ranges from 46 to 57 degrees F. (8 to 14 degrees C.), mean annual precipitation ranges from 32 to 42 inches (813 to 1067 mm), frost free days range from 170 to 200 days, and elevation ranges from 350 to 1020 feet (107 to 311 meters) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Atlas, Blair, Coatsburg, Elco, Winfield, Fayette, Hickory, Keller, Keomah, Rozetta, and Ursa soils. The somewhat poorly drained Atlas and Coatsburg soils and the well drained Hickory and Ursa soils are downslope. Atlas and Coatsburg soils are shallower to the paleosol and Coatsburg soils have a mollic epipedon. Hickory soils average more than 15 percent sand in the particle-size control section and do not contain a paleosol. Ursa soils average more than 35 percent clay in the particle-size control section. The somewhat poorly drained Blair soils are on similar landform positions but have the major part of their solum formed in water-worked sediments that lie above the till and beneath the Peoria loess. Elco soils are moderately well drained and are on similar landform positions. The moderately well drained Winfield, the well drained Rozetta and Fayette soils, and the somewhat poorly drained Keomah soils formed entirely in loess and are upslope on higher backslopes and shoulders or on crests of summits. The somewhat poorly drained Keller soils have a mollic epipedon, are in biosequence with Fishhook soils, and are on similar landform positions.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. The seasonal high water table is 1.0 foot to 2.0 feet (30 to 61 cm) below the surface in spring during normal years. The potential for surface runoff is low to medium. Saturated hydraulic conductivity is moderately high or high (4.23 to 14.11 micrometers per second) in the loess and moderately low or moderately high (0.42 to 1.41 micrometers per second) in the till. Permeability is moderate (0.6 to 2 inches per hour) in the loess and slow (0.06 to 0.2 inches per hour) in the till.
USE AND VEGETATION: Many areas are used for cultivated crops. Corn, soybeans, and small grain are the principal crops. Other areas are used for forage, hay, pasture, or woodland. Native vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: Western, northwestern, and southwestern Illinois. Extent is moderate in MLRA's 108B, 113, 114B, 115A and 115C. The type location is in MLRA 115C.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Stephenson County, Illinois, 1969.
REMARKS: The 2Bt or 2Btg horizon of the Fishhook soils is the lower part of a modern solum superimposed upon a Sangamon paleosol in the Illinoian or Pre-Illinoian till. Many of the properties of those horizons are believed to be inherited from the paleosol. The variability of the properties is related to the geologic truncation of the paleosol before it was buried by loess, and to the extent of modern soil development in the old materials. Calcium and other bases have been replenished in some pedons after burial by loess through infiltration. It is difficult to differentiate the properties of the lower part of the modern solum from those of the paleosol in many pedons. Some pedons contain a thin layer of loamy pedisediment between the loess and the till.
Diagnostic horizons and features recognized in this pedon are:
ochric epipedon - the zone from the surface of the soil to a depth of 6 inches (Ap horizon); argillic horizon - the zone from about 6 inches to a depth of more than 82 inches (Bt1, Bt2, Bt3, 2Bt4, 2Bt5, 2Bt6, 2Bt7, and 2Btg horizons); udic moisture regime; mesic temperature regime.
This pedon was checked in the field by RDC 5/25/95 and adjustments were made in the description on depth of soil development, colors and redoximorphic features. CLL, RLT.
ADDITIONAL DATA: Data for different pedons of Fishhook from Brown County and Stephenson County are on file at the NRCS Region 11 MLRA Office, Indianapolis, Indiana.