Soil Survey of McHenry County, Illinois Part I - Soil Data Mart

McHenry County, Illinois—Part I 99
(10YR 2/1) iron and manganese oxide concretions
throughout; common fine distinct yellowish brown
(10YR 5/6) masses of iron accumulation and
grayish brown (2.5Y 5/2) iron depletions in the
matrix; 1 percent gravel; neutral; clear smooth
boundary.
Bt3—24 to 34 inches; dark grayish brown (10YR 4/2)
silty clay; moderate medium prismatic structure
parting to moderate medium angular blocky; firm;
common very fine and few fine roots; many
distinct dark grayish brown (2.5Y 4/2) clay films on
faces of peds; few fine black (10YR 2/1) iron and
manganese oxide concretions throughout;
common fine distinct yellowish brown (10YR 5/6)
masses of iron accumulation and grayish brown
(2.5Y 5/2) iron depletions in the matrix; 1 percent
gravel; very slightly effervescent; moderately
alkaline; gradual wavy boundary.
Bk—34 to 43 inches; brown (10YR 5/3) silty clay;
moderate medium prismatic structure; firm;
common very fine roots; common fine white
(10YR 8/1) masses of carbonate; many fine and
medium distinct yellowish brown (10YR 5/6)
masses of iron accumulation in the matrix;
common fine and medium distinct grayish brown
(2.5Y 5/2) iron depletions in the matrix; 1 percent
gravel; slightly effervescent; moderately alkaline;
gradual wavy boundary.
C—43 to 63 inches; brown (10YR 5/3) silty clay;
massive; firm; many fine and medium distinct
yellowish brown (10YR 5/6) masses of iron
accumulation in the matrix; common fine and
medium distinct grayish brown (2.5Y 5/2) iron
depletions in the matrix; 1 percent gravel; slightly
effervescent; moderately alkaline.
MLRA Series Range in Characteristics
Depth to carbonates: 20 to 40 inches
Thickness of the solum: 24 to 50 inches
Ap horizon:
Hue—10YR
Value—3 or 4
Chroma—1 to 3
Texture—silt loam or silty clay loam
Bt horizon:
Hue—10YR or 2.5Y
Value—4 to 6
Chroma—2 to 4
Texture—silty clay, clay, or silty clay loam
C horizon:
Hue—10YR or 2.5Y
Value—4 to 6
Chroma—2 to 4
Texture—silty clay, silty clay loam, clay loam, or
clay
228B—Nappanee silt loam, 2 to 4 percent
slopes
Setting
Landform: Lake plains and moraines
Position on the landform: Summits, shoulders, and
backslopes
Slope range: 2 to 4 percent
A typical soil series description with range in
characteristics is included, in alphabetical order, in this
section. Additional information specific to this map
unit, such as horizon depth and textures, is available
in the “Soil Properties” section in Part II of this
publication.
Composition
Nappanee and similar soils: 85 percent
Dissimilar soils: 15 percent
Similar soils:
• soils that are moderately eroded
• soils that have a darker surface layer
• soils that contain less clay in the profile
• soils that have a seasonal high water table at a
depth of more than 2 feet
Dissimilar soils:
• the somewhat excessively drained Casco and well
drained Fox soils in the higher positions on the
landform
Management
For general and detailed information about
managing this map unit, see the following sections in
Part II of this publication:
• “Agronomy” section
• “Forestland” section
• “Wildlife Habitat” section
• “Engineering” section
• “Soil Properties” section
Octagon Series
Drainage class: Well drained
Permeability: Moderate in the upper part and
moderately slow in the lower part
Landform: Moraines and till plains
Parent material: Thin mantle of silty material and the
underlying loamy till