LOCATION KNIGHT ILEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Argiaquic Argialbolls
TYPICAL PEDON: Knight silt loam - on a south facing slope about 1 percent in a cultivated field at an elevation of about 530 feet above mean sea level. (Colors are for moist soil.)
Ap--0 to 25 centimeters (0 to 10 inches); black (10YR 2/1) silt loam; moderate very fine subangular blocky structure (compacted); friable; few fine roots; neutral; abrupt smooth boundary. [Combined thickness of the A horizons is 25 to 61 centimeters (10 to 24 inches)]
Eg--25 to 41 centimeters (10 to 16 inches); gray (10YR 5/1) silt loam; moderate medium platy structure; friable; few fine roots; few distinct dark grayish brown (10YR 4/2) organic stains on faces of peds; few fine distinct dark brown (7.5YR 3/4) extremely weakly cemented iron-manganese accumulations in the matrix; neutral; clear smooth boundary. [Combined thickness of the Eg horizons is 13 to 51 centimeters (5 to 20 inches)]
BEg--41 to 56 centimeters (16 to 22 inches); light brownish gray (2.5Y 6/2) silt loam; moderate coarse platy structure parting to moderate fine subangular blocky; friable; few fine roots; few distinct dark grayish brown (10YR 4/2) organic stains on faces of peds; few fine prominent dark brown (7.5YR 3/4) extremely weakly cemented iron-manganese accumulations in the matrix; neutral; gradual smooth boundary. [0 to 23 centimeters (0 to 9 inches thick)]
Btg1--56 to 89 centimeters (22 to 35 inches); light brownish gray (2.5Y 6/2) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; friable; few faint gray (2.5Y 6/1) silt coats on faces of peds, common distinct grayish brown (10YR 5/2) clay films on faces of peds and few distinct dark grayish brown (10YR 4/2) clay films on surfaces along pores; few fine distinct black (7.5YR 2.5/1) iron-manganese concretions in the matrix and few fine prominent strong brown (7.5YR 4/6) extremely weakly cemented iron-manganese accumulations in the matrix; slightly acid; gradual smooth boundary.
Btg2--89 to 135 centimeters (35 to 53 inches); varigated strong brown (7.5YR 5/6) and (7.5YR 4/6) and light brownish gray (2.5Y 6/2) silty clay loam; weak coarse prismatic structure; friable; few faint gray (2.5Y 6/1) silt coats on faces of peds; few distinct grayish brown (10YR 5/2) clay films on faces of peds and few distinct dark grayish brown (10YR 4/2) clay films on surfaces along pores; few fine distinct black (7.5YR 2.5/1) iron-manganese concretions in the matrix; slightly acid; gradual smooth boundary. [Combined thickness of the Btg horizon is 56 to 89 centimeters (22 to 35 inches)]
BCg--135 to 178 centimeters (53 to 70 inches); varigated light brownish gray (2.5Y 6/2) and strong brown (7.5YR 5/6) and (7.5YR 4/6) silt loam; weak coarse prismatic structure; friable; few distinct dark grayish brown (10YR 4/2) clay films on surfaces along pores; few fine distinct black (7.5YR 2.5/1) iron-manganese concretions and few fine distinct strong brown (7.5YR 4/6) masses of oxidized iron in the matrix; neutral; abrupt smooth boundary. [0 to 51 centimeters (0 to 20 inches in thickness)]
2Cg1--178 to 201 centimeters (70 to 79 inches); grayish brown (10YR 5/2) stratified sandy clay loam and sandy loam; massive; friable; few fine prominent strong brown (7.5YR 4/6) masses of oxidized iron and few fine distinct black (7.5YR 2.5/1) iron-manganese concretions in the matrix; 5 percent gravel; neutral; gradual smooth boundary.
2Cg2--201 to 224 centimeters (79 to 88 inches); dark grayish brown (10YR 4/2) gravelly sandy clay loam; massive; friable; few fine distinct black (7.5YR 2.5/1) iron-manganese concretions and few fine prominent strong brown (7.5YR 4/6) extremely weakly cemented iron-manganese accumulations in the matrix; 15 percent gravel, neutral.
TYPE LOCATION: Logan County, Illinois; about 4 miles south east of Lawndale, 330 feet north and 2170 feet east of the southwest corner of sec. 9, T.20 N., R.1W.; lat. 40 degrees 11 minutes 39 seconds N. and long. 89 degrees 12 minutes 53 seconds W. or UTM zone 16 311490E 4451657N, NAD 83
RANGE IN CHARACTERISTICS: The mollic epipedon is 10 to 24 inches thick. The depth to the top of the argillic horizon is greater than 20 inches. The depth to the base of the argillic horizon ranges from 45 to 60 inches. Some pedons have development into the underlying loamy or coarse textured material. The particle size control section averages 27 to 35 percent clay. The soil horizons to a depth of 54 inches have less than 10 percent sand. Sand content in the underlying material ranges from 15 to 95 percent. The depth to carbonates is greater than 54 inches.
The Ap and A horizons have hue of 10YR, value of 2 or 3, and chroma of 1 or 2. It is silt loam. Reaction ranges from strongly acid to neutral.
The Eg horizon has hue of 10YR. 2.5Y or 5Y, value of 4 to 6, and chroma of 2 or less. The lower part commonly has redox accumulations of higher chroma. Texture is silt loam. Reaction ranges from strongly acid to neutral.
The Btg or BCg horizon has hue of 10YR, 2.5Y or 5Y, value of 4 to 6, and chroma of 2 or less. Redoximorphic features have higher chroma. Texture is dominantly silty clay loam, but is silt loam in the upper or lower parts in some pedons. The clay content ranges from 22 to 35 percent. Reaction ranges from strongly acid to neutral.
Some pedons have a 2BCg horizon with colors similar to the 2C or 2Cg horizons.
The 2C or 2Cg horizon has hue of 10YR, 2.5Y or 5Y, value of 4 to 6, and chroma of 1 to 6. It is typically stratified sandy clay loam, sandy loam, silt loam, loam, sand, or their gravelly or very gravelly analogs. Rock fragments range from 0 to 60 percent. The clay content ranges from 5 to 30 percent. Reaction ranges from slightly acid to moderately alkaline. Carbonates are present in some pedons.
COMPETING SERIES: These are the Corley, Ebbert, Edgington, Marissa, Normal, Speed, Thorp, and Vesser series. Corley soils have part of the mollic epipedon below the albic horizon. Ebbert, Marissa, and Speed soils have mean annual soil temperature of more than 55 degrees in the soil temperature control section. Edgington soils do not have loamy materials within a depth of 72 inches. Normal soils have a matrix color with greater than 2 chroma in one or more horizons in the upper part of the series control section. Thorp soils have horizons with more than 10 percent sand within a depth of 54 inches. Vesser soils contain more than 10 percent sand in the upper part of the series control section.
GEOGRAPHIC SETTING: Knight soils are on outwash plains, stream terraces, and flood plain steps. Slopes are usually less than 2 percent. They formed in less than 72 inches of loess or silty material and are underlain by loamy or coarse textured outwash. Mean annual air temperature ranges from about 49 to 58 degrees F. and annual precipitation ranges from about 24 to 51 inches near the type location.
GEOGRAPHICALLY ASSOCIATED SOILS: They are the Elburn, Plano, Proctor, and Tama soils. All lack E horizons, are better drained, and are at somewhat higher elevations in the same general landscape.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. Potential for surface runoff is negligible. Permeability is moderately slow or moderate (moderately high saturated hydraulic conductivity) in the upper part of the solum and moderate to moderately rapid (moderately high to high saturated onductivity) in the lower part of the solum and in the substratum. In normal years, the apparent seasonal high water table is at the surface to 1 foot below the surface in spring. Ponding depth is generally less than 0.5 foot above the surface. A rarely flooded phase has is recognized.
USE AND VEGETATION: Most areas are cultivated. Principal crops are corn, soybeans, and small grains. Native vegetation is prairie grasses tolerant of prolonged periods of wetness.
DISTRIBUTION AND EXTENT: Central and northeastern Illinois. The extent is small in MLRAs 108A and 108B
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Kendall County, Illinois, 1941.
REMARKS: With this update (3/2006) the type location is relocated to a new site. Diagnostic horizons and features recognized in this pedon are: Mollic epipedon -- the zone from the surface to a depth of 25 centimeters (10 inches) Albic horizon -- the zone from 25 to 56 centimeters [10 to 22 inches (Eg and BEg horizons)] Argillic horizon -- the zone from 56 to 135 centimeters [22 to 53 inches (Btg1 and Btg2 horizon)]