LOCATION AZTALAN WI

Established Series
Rev. HFG-AAC
09/2023

AZTALAN SERIES

The Aztalan series consists of very deep, somewhat poorly drained soils formed in loamy outwash and in the underlying mostly clayey and silty stratified lacustrine deposits on glacial lake basins and stream terraces. Slope ranges from 0 to 6 percent. Mean annual precipitation is about 762 mm (30 inches). Mean annual air temperature is about 8.9 degrees C (48 degrees F).

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

TYPICAL PEDON: Aztalan loam - on a 2 percent slope in a cultivated field at an elevation of about 249 meters (818 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 18 cm (0 to 7 inches); black (10YR 2/1) loam, grayish brown (10YR 5/2) dry; cloddy with areas of weak fine granular and weak fine subangular blocky structure; friable; many fibrous roots; neutral; abrupt smooth boundary.

A--18 to 31 cm (7 to 12 inches); very dark brown (10YR 2/2) loam, grayish brown (10YR 5/2) dry; weak fine and medium subangular blocky structure; friable; many fibrous roots; neutral; clear smooth boundary. [Combined thickness of the Ap and A horizons ranges from 25 to 41 cm (10 to 16 inches).]

Bt1 --31 to 41 cm (12 to 16 inches); brown (10YR 4/3) loam; moderate fine and medium subangular blocky structure; friable; many distinct very dark grayish brown (10YR 3/2) organic coatings on faces of peds; common fine fibrous roots; few faint brown (10YR 4/3) clay films on faces of peds; few fine faint dark yellowish brown (10YR 4/4)and prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; few fine distinct gray (10YR 5/1) iron depletions in the matrix; neutral; clear wavy boundary. [8 to 20 cm (3 to 8 inches) thick]

Bt2--41 to 69 cm (16 to 27 inches); olive brown (2.5Y 4/4) and brown (10YR 4/3) loam; moderate medium subangular blocky structure; firm; few fibrous roots; few faint clay films on faces of peds; common fine faint dark yellowish brown (10YR 4/4) distinct yellowish brown (10YR 5/6) and prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; common fine distinct gray (10YR 5/1) iron depletions in the matrix; neutral; abrupt smooth boundary. [13 to 31 cm (5 to 12 inches) thick]

2Bt3--69 to 94 cm (27 to 37 inches); brown (10YR 5/3) silty clay loam; weak coarse prismatic structure parting to moderate fine and medium subangular and angular blocky; very firm; few fibrous roots and few fine taproots; few faint clay films on faces of peds; many fine prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; many fine distinct gray (10YR 6/1) iron depletions in the matrix; slightly alkaline; gradual smooth boundary. [10 to 28 cm (4 to 11 inches) thick]

2Bt4--94 to 109 cm (37 to 43 inches); brown (7.5YR 4/4) and dark yellowish brown (10YR 4/4) silty clay loam; weak coarse prismatic structure parting to weak medium angular blocky; firm; few taproots; few faint gray (5Y 5/1) clay films on vertical faces of peds; common fine and medium distinct yellowish brown (10YR 5/6) and prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; common fine and medium distinct light brownish gray (10YR 6/2) iron depletions in the matrix; slightly alkaline; clear wavy boundary. [8 to 15 cm (3 to 6 inches) thick]

2C--109 to 152 cm (43 to 60 inches); brown (7.5YR 5/4) and strong brown (7.5YR 5/6) silty clay loam with strata of silt and silty clay; massive breaking to thick plates along depositional strata; firm; common medium prominent yellowish brown (10YR 5/8) masses of oxidized iron in the matrix; common medium prominent grayish brown (10YR 5/2) iron depletions in the matrix; strongly effervescent; moderately alkaline.

TYPE LOCATION: Walworth County, Wisconsin; about 4 miles east of Whitewater; 100 feet north and 50 feet west of the southeast corner of sec. 1, T. 4 N., R. 15 E. USGS Whitewater, Wisconsin topographicquadrangle; lat. 42 degrees 49 minutes 42 seconds N., and long. 88 degrees 39 minutes 34 seconds W., NAD 27.

RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon: 25 to 51 cm (10 to 20 inches)
Thickness of the loamy outwash mantle: 46 to 91 cm (18 to 36 inches)
Depth to the base of the argillic horizon: 61 to 135 cm (24 to 53 inches)
Depth to carbonates: 61 to 135 cm (24 to 53 inches)
Particle-size control section: averages 18 to 27 percent clay, 35 to 60 percent fine sand or coarser
Volume of gravel in the loamy outwash: 0 to 10 percent; no rock fragments in the underlying lacustrine deposit
Reaction: slightly acid to slightly alkaline in the upper part of the soil, slightly alkaline or moderately alkaline in the lower part
Carbonates: in the C horizon, in the lower part of the B horizon in some pedons
Redox features: saturation and redoxomorphic features within 41 cm (16 inches) of the soil surface or saturation directly below the mollic epipedon in one or more horizons with a total thickness of 15 cm (6 inches) or more with redoxomorphic depletions

A horizon:
Hue: 10YR
Value: 2 or 3
Chroma: 1 or 2
Texture: typically loam, but sandy loam, fine sandy loam, and silt loam within the range

Bt horizon:
Hue: 10YR or 2.5Y
Value: 4 or 5
Chroma: 3 or 4
Texture: loam, fine sandy loam, sandy loam or sandy clay loam

2Bt horizon:
Hue: typically 7.5YR, 10YR or 2.5Y
Value: 4 or 5
Chroma: 3 to 6, some pedons have subhorizons with dominant chroma of 1 or 2
Texture: typically silty clay loam, but, in some pedons, it has thin strata of finer or coarser textures

2C horizon:
Hue: 7.5YR, 10YR or 2.5Y
Value: 5 or 6
Chroma: 1 to 6
Texture: typically silty clay loam with thin strata of finer or coarser textures
Clay content: averages more than 25 percent

COMPETING SERIES: These are the Andres, Darroch, Francesville, Gilboa, Houstenader, La Hogue, Lahoguess, Le Sueur, Marcellon, Newhaven, Odell, Protivin, and Vigar. Andres soils average more than 27 percent clay in the particle_size control section; Darroch and La Hogue soils have less than 20 percent clay in the lower part of the series control section. Francesville and Odell soils have a densic contact at 61 to 102 cm (24 to 40 inches). Gilboa, Le Sueur, and Marcellon soils are not stratified in the lower part of the series control section. In addition, Le Sueur and Marcellon soils have rock fragments there and Marcellon soils have less than 20 percent clay there. Houstenader soils do not have carbonates within the series control section and have gravel in the lower part of the series control section. Lahoguess soils have 80 to 98 percent sand in the lower part of the series control section. Newhaven soils have soils have lamellae in the lower part of the series control section. Protivin soils average more than 28 percent clay in the particle-size control section. Vigar soils have mollic epipedons more than 24 inches thick.

GEOGRAPHIC SETTING: Aztalan soils are on glacial lake basins and stream terraces. Slope ranges from 0 to 6 percent. These soils formed in a mantle of loamy outwash and in mostly silty and clayey stratified lacustrine deposits. Mean annual precipitation ranges from 660 to 890 mm (26 to 35 inches). Mean annual air temperature ranges from 7.8 to 10.0 degrees C (46 to 50 degrees F).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kibbie, Martinton, and Navan soils. The poorly drained and very poorly drained Navan soils form a drainage sequence with Aztalan soils and are the most common associates in the nearly level and gently undulating landscapes. Aztalan, Kibbie, and Martinton are soils often associated in the landscape but cannot be identified with or separated one from another by specific relief; consequently, all reflect the varying influences of stratification and overwash. Kibbie soils formed in thinly stratified silty and very fine sandy deposits, whereas Martinton soils formed in stratified silty and clayey deposits.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. Surface runoff is medium or low. Saturated hydraulic conductivity is moderately high to high (4.23 to 14.11 micrometers per second) in the loamy outwash mantle and moderately high (1.41 to 4.23 micrometers per second) in the underlying lacustrine deposits. Permeability is moderate in the loamy outwash mantle and moderately slow in the underlying stratified lacustrine deposit. These soil have a perched seasonal high water table at a depth of 31 to 76 cm (1 to 2.5 feet) for some time in most years.

USE AND VEGETATION: Much of this soil is used for cropland. Common crops are corn, small grains, and hay. Native vegetation is prairie grasses with a few trees.

DISTRIBUTION AND EXTENT: MLRAs 95B and 110 in southeastern Wisconsin. The Aztalan soils are of moderate extent.

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

SERIES ESTABLISHED: Walworth County, Wisconsin, 1966.

REMARKS:
7/04 The concept of this series is a mantle of loamy outwash over silty and clayey stratified lacustrine deposits. In some county surveys, soils that formed in loamy outwash over clayey till have also been correlated as Aztalan. This includes at least part of the acreage of Aztalan in the Kenosha-Racine and Ozaukee soil surveys and possibly the Milwaukee-Waukesha and other surveys. These areas need to be correlated to another (new?) series when the surveys are updated.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 31 cm (0 to 12 inches) (AP and A ); argillic horizon - 31 to 109 cm (12 to 43 inches) (Bt1, Bt2, 2Bt3, and 2Bt4); aquic feature redox features and saturation within 16 inches of the surface.

National Cooperative Soil Survey
U.S.A.