LOCATION NACHUSA IL

Established Series
Rev. HWG-SEZ-JWS
02/2011

NACHUSA SERIES

The Nachusa series consists of deep, somewhat poorly drained soils that formed in a thin layer of loamy aeolian deposits and in glacial till that contains a paleosol on till plains. They are moderately permeable in the upper loamy sediments and moderately slowly permeable in the lower paleosolic till. Slope ranges from 0 to 3 percent. Mean annual temperature is 9.4 degrees C (49 degrees F), and mean annual precipitation is about 864 mm (34 inches).

TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Aquic Argiudolls

TYPICAL PEDON: Nachusa silt loam - on a northwest-facing slope of 1 percent in a cultivated field. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 28 cm (0 to 11 inches); black (10YR 2/1) silt loam, dark grayish brown (10YR 4/2) dry; moderate fine granular structure; friable; common fine roots; neutral; abrupt smooth boundary. [Total thickness of the A horizon is 25 to 41 cm (10 to 16 inches).]

BA--28 to 41 cm (11 to 16 inches); dark grayish brown (10YR 4/2) silt loam, light gray (10YR 7/2) dry; moderate fine subangular blocky structure parting to moderate fine granular; friable; few fine distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; common fine roots; common thin very dark gray (10YR 3/1) organic coats on faces of peds; neutral; clear smooth boundary. [0 to 15 cm (0 to 6 inches) thick]

Bt1--41 to 58 cm (16 to 23 inches); dark grayish brown (10YR 4/2) silty clay loam; weak medium prismatic structure parting to moderate fine subangular blocky; friable; common fine distinct yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; ommon fine roots; common faint dark gray (10YR 4/1) clay films on faces of peds; few fine dark concretions (Fe and Mn oxides); moderately acid; clear smooth boundary. [Thickness of the Bt horizon is 18 to 38 cm (7 to 15 inches).]

2Bt2--58 to 84 cm (23 to 33 inches); yellowish brown (10YR 5/8) clay loam; moderate medium prismatic structure parting to moderate medium angular blocky; firm; few fine prominent grayish brown (2.5Y 5/2) iron depletions and few fine faint strong brown (7.5YR 5/8) masses of oxidized iron in the matrix; common fine roots; common fine prominent dark gray (10YR 4/1) clay films on vertical and horizontal faces of peds; common fine dark concretions (Fe and Mn oxides); slightly acid; clear smooth boundary.

2Bt3--84 to 117 cm (33 to 46 inches); yellowish brown (10YR 5/8) clay loam; moderate medium prismatic structure; firm; few fine prominent grayish brown (2.5Y 5/2) iron depletions and few fine distinct strong brown (7.5YR 5/8) masses of oxidized iron in the matrix; few fine roots; few thin dark gray (10YR 4/1) clay films on both vertical and horizontal faces of peds; thick gray (10YR 5/1) and very dark gray (10YR 3/1) fillings in root channels; few fine dark concretions (Fe-Mn oxides); neutral; clear smooth boundary.

2Bt4--117 to 152 cm (46 to 60 inches); yellowish brown (10YR 5/8) loam with lenses of sandy loam; weak coarse prismatic structure; friable; common fine distinct gray (10YR 6/1) iron depletions in the matrix; common thin gray (10YR 5/1) clay films on faces of peds; neutral. [Combined thickness of the 2Bt horizon is 51 to 127 cm (20 to 50 inches).]

TYPE LOCATION: Lee County, Illinois; 3/4 mile northwest of Amboy; 246 feet east and 952 feet north of the southwest corner of sec. 10, T. 20 N., R. 10 E.

RANGE IN CHARACTERISTICS:
Thickness of the solum: 122 to 183 cm (48 to 72 inches), and depends upon the amount of truncation of the paleosol.
Thickness of the mollic epipedon: 25 to 41 cm (10 to 16 inches)
Thickness of the aeolian sediments over the paleosol: 51 to 86 cm (20 to 34 inches)
Average content of clay in the control section: between 25 and 35 percent
Average content of fine sand or coarser sand in the control section: between 15 and 40 percent

A horizon:
Hue: 10YR
Value: 2 or 3 moist and 4 or 5 dry
Chroma: 1 to 3
Texture: typically silt loam but some horizons are loam.
Reaction: medium acid to neutral

Some pedons have A12 or A3 horizons 10 to 20 cm (4 to 8 inches) thick.

BA horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 2 or 3
Texture: silt loam
Other features: redoximorphic features of yellowish brown or strong brown
Other features: Clay films are present on the faces of peds in some pedons.

Bt horizon:
Hue: 10YR or 2.5Y
Value: 4, 5 or 6
Chroma: 2 to 4
texture: commonly silty clay loam but some pedons include silt loam in the upper part and grade to clay loam or loam in the lower part.
Reaction: commonly medium acid but ranges from very strongly acid to neutral.

2Bt horizon:
Hue: typically 7.5YR or 10YR, but includes pedons or subhorizons with hue of 2.5Y or 5Y
Value: 4 to 6
Chroma: 2 to 8
Texture: commonly clay loam but some subhorizons range to loam or clay in the upper part; typically loam but ranges to silt loam or clay loam in the lower part
Reaction: typically moderately acid in the upper part but ranges from strongly acid to neutral; moderately acid to neutral in the lower part
Redoximorphic features: present throughout
Other features: Many of the properties of the 2Bt horizon are believed to be inherited from a paleosol of probable Sangamonian age truncated by Wisconsinan glacial meltwaters.

2C horizon:
Hue: 7.5YR or 10YR in the matrix
Value: 4 to 6
Chroma: 4 to 8
Texture: commonly loam but ranges to clay loam. Some pedons contain lenses of sandy loam, loamy sand, or silt loam.
Reaction: slightly acid to moderately alkaline and commonly lacks free carbonates above a depth of 152 cm (60 inches).

COMPETING SERIES: These are the Aurand, Crane, Mokena, Nenno, and Tiderishi series. Aurand soils have a densic contact within the series control section. Crane soils have more than 15 percent rock fragments in the lower part of the series control section. Mokena soils average more than 40 percent clay in the lower part of the series control section. Nenno soils have less than 61 cm (24 inches) thick solum to the base of the argillic horizon. Tiderishi soils have rock fragments in the lower part of the series control section.

GEOGRAPHIC SETTING: Nachusa soils are on till plains on uplands. Slope gradients range from 0 to 3 percent. They formed in 51 to 86 cm (20 to 34 inches) of loamy aeolian sediments and in paleosols formed in glacial till presumed to be of Illinoian age. Mean annual temperature ranges from 8.3 to 11.1 degrees C (47 to 52 degrees F), and mean annual precipitation ranges from 813 to 914 mm (32 to 36 inches).

GEOGRAPHICALLY ASSOCIATED SOILS: These are Odell, Parr, Prairieville, and Wolcott soils. Somewhat poorly drained Odell soils and well drained Parr soils have thinner sola and commonly occur downslope from Nachusa soils and commonly are adjacent to major drainageways. The moderately well drained Prairieville and poorly drained Wolcott soils are in a drainage sequence with Nachusa soils.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. Runoff is slow. Saturated hydraulic conductivity is moderately high to high (4.23 to 14.11 micrometers per second) in the loamy aeolian sediments and moderately high (1.41 to 4.23 micrometers per second) in the paleosolic till. Permeability is moderate in the loamy aeolian sediments and moderately slow in the paleosolic till. Water commonly is perched above the paleosolic horizon during winter and spring months.

USE AND VEGETATION: Mainly cropped. Corn, meadow, small grain, and soybeans are the principal crops. Native vegetation was prairie grasses.

DISTRIBUTION AND EXTENT: MLRA 108B in northern Illinois. The soils of this series are not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana

SERIES ESTABLISHED: Lee County, Illinois, 1981.

REMARKS: These soils are borderline between fine-loamy and fine.

ADDITIONAL DATA: Mechanical analysis data are on file in the Illinois state office for two pedons including the typical pedon.

National Cooperative Soil Survey
U.S.A.