LOCATION TAMALCO ILEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aquic Natrudalfs
TYPICAL PEDON: Tamalco silt loam - on a north-facing slope of about 3 percent in a cultivated field, at an elevation of about 194 meters (636 feet) above mean sea level.(Colors are for moist soil unless otherwise stated.)
Ap--0 to 15 centimeters (0 to 6 inches); very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; friable; many fine roots; 2 percent exchangeable sodium; very strongly acid; abrupt smooth boundary. (15 to 23 cm or 6 to 9 inches thick)
E--15 to 23 centimeters (6 to 9 inches); brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; weak thin platy structure; friable; many fine roots; few fine prominent reddish brown (2.5YR 4/4) masses of oxidized iron-manganese throughout; 3 percent exchangeable sodium; very strongly acid; abrupt smooth boundary. (0 to 15 cm or 0 to 6 inches thick)
Bn\E--23 to 28 centimeters (9 to 11 inches); brown (10YR 5/3) silty clay loam (B); moderate medium subangular blocky structure; firm; many fine roots; many prominent gray (10YR 6/1) silt coats on faces of peds and as fillings between peds, light gray (10YR 7/1) (dry) (E); common fine prominent reddish brown (2.5YR 4/4) masses of oxidized iron-manganese throughout; 6 percent exchangeable sodium; very strongly acid; abrupt smooth boundary. (0 to 13 cm or 0 to 5 inches thick)
Btn--28 to 43 centimeters (11 to 17 inches); reddish brown (5YR 4/4) silty clay; moderate medium prismatic structure parting to moderate fine angular blocky; firm; many fine roots; common distinct dark brown (7.5YR 3/2) organo-clay films on faces of peds; 10 percent exchangeable sodium; strongly acid; clear smooth boundary. (13 to 38 cm or 5 to 15 inches thick)
Btkn--43 to 71 centimeters (17 to 28 inches); pale brown (10YR 6/3) silty clay loam; weak fine and medium angular blocky structure; firm; common fine roots; common distinct very dark grayish brown (10YR 3/2) organo-clay films on faces of peds and fillings in root channels; few fine faint light brownish gray (10YR 6/2) iron depletions, many fine faint brown (10YR 5/3) masses of oxidized iron-manganese, and few fine distinct yellowish brown (10YR 5/6) masses of oxidized iron throughout; common medium distinct white (10YR 8/1) concretions of calcium carbonates throughout; strongly effervescent on the concretions; 18 percent exchangeable sodium; slightly alkaline; clear smooth boundary.
Btkng--71 to 89 centimeters (28 to 35 inches); gray (10YR 6/1) silt loam; weak coarse angular blocky structure; firm; few fine roots; few distinct grayish brown (10YR 5/2) clay films on faces of peds; many medium prominent yellowish brown (10YR 5/6) masses of oxidized iron and few fine prominent black (10YR 2/1) masses of manganese throughout; few medium faint white (10YR 8/1) concretions of calcium carbonates throughout; strongly effervescent on the concretions; 26 percent exchangeable sodium; moderately alkaline; clear smooth boundary. [The combined thickness of the B horizons is 30 to 102 cm (12 to 40 inches).]
BCng--89 to 107 centimeters (35 to 42 inches); light brownish gray (10YR 6/2) silt loam; weak coarse subangular blocky structure; friable; many fine prominent strong brown (7.5YR 5/6) masses of oxidized iron and few fine prominent black (10YR 2/1) masses of manganese throughout; 24 percent exchangeable sodium; moderately alkaline; gradual smooth boundary. (0 to 38 cm or 0 to 15 inches thick)
2Cng--107 to 137 centimeters (42 to 54 inches); grayish brown (10YR 5/2) silt loam; massive; friable; many medium distinct brown (7.5YR 4/4) masses of oxidized iron-manganese throughout; few fine distinct black (10YR 2/1) masses of manganese throughout; 18 percent exchangeable sodium; moderately alkaline; gradual smooth boundary. (0 to 38 cm or 0 to 15 inches thick)
3Cn1--137 to 152 centimeters (54 to 60 inches); brown (7.5YR 4/4) silt loam; massive, friable; common medium distinct dark grayish brown (10YR 4/2) iron depletions and few fine prominent black (10YR 2/1) masses of manganese throughout; 13 percent exchangeable sodium; 1 percent gravel; moderately alkaline; gradual smooth boundary.
3Cn2--152 to 191 centimeters (60 to 75 inches); brown (7.5YR 4/4) silt loam; massive, friable; few fine prominent black (10YR 2/1) masses of manganese throughout; 9 percent exchangeable sodium; 1 percent gravel; slightly alkaline;; clear smooth boundary.
3C--191 to 213 centimeters (75 to 84 inches); brown (7.5YR 4/4) loam; massive, friable, 5 percent exchangeable sodium; 1 percent gravel; slightly alkaline.
TYPE LOCATION: Montgomery County, Illinois; about 4.8 kilometers (3 miles) north and 0.8 kilometer (0.5 mile) west of Hillsboro; 702 meters (2,300 feet) west and 24 meters (78 feet) south of the northeast corner of sec 26, T. 9 N., R. 4 W USGS Butler, Illinois topographic quadrangle; lat.39 degrees 12 minutes 8.3 seconds N. and long. 89 degrees 30 minutes 1.8 seconds W.; UTM Zone 16, 284081 easting and 4342209 northing, NAD 83.
RANGE IN CHARACTERISTICS:
Depth to the base of soil development: Typically 91 to 152 cm (36 to 60 inches), but ranges from 76 to more than 200 cm (30 to more than 80 inches).
Loess thickness: Typically, 91 cm to 152 cm (36 to 60 inches), but ranges from 76 to 200 cm (30 to 80 inches).
Natric horizon: A concentration of exchangeable sodium of 15 percent or more, or SAR of 13 percent or more is within the upper 40 cm (16 inches) of the top of the natric horizon, and typically is at depths of 18 to 61 cm (7 to 24 inches), but in some pedons it is as deep as 76 cm (30 inches) below the soil surface. Carbonates are common in the natric horizon but are not present everywhere.
Depth to base of the natric horizon: Typically 61 to 127 cm (24 to 50 inches); but ranges from 30 to 102 cm (12 to 40 inches) in thickness.
Clay content: The particle size control section averages between 35 and 42 percent clay, but individual subhorizons contain as much as 45 percent.
Sand content: The particle size control section averages less than 10 percent sand.
Redoximorphic features: Iron depletions with a chroma of 2 or less are within 25 cm (10 inches) of the top of the natric horizon.
The Ap or A horizons:
Hue: 10YR
Value: 3 to 5
Chroma: 2 or 3
Texture: Typically silt loam but ranges to silty clay loam on eroded pedons.
Clay content: Typically 12 to 27 percent, but ranges to 35 percent on eroded pedons.
Sand content: less than 10 percent
Reaction: Very strongly acid to slightly acid, but is neutral or slightly alkaline where limed.
Eroded pedons have hue of 10YR, 7.5YR or 5YR, value of 4 or 5 and chroma of 2 to 4.
The E horizon, where present:
Hue: 10YR
Value: 4 to 6
Chroma: 2 or 3
Texture: Silt loam
Clay content: 12 to 25 percent
Sand content: less than 10 percent
Reaction: Very strongly acid to neutral
Some pedons have a BE or Btn/E horizon.
Btn horizon(upper part):
Hue: 5YR or 7.5YR, less commonly 10YR
Value: 4 or 5
Chroma: Typically 4, but ranges from 3 to 6
Texture: Silty clay or silty clay loam
Clay content: 35 to 45 percent
Sand content: less than 10 percent
Reaction: Very strongly acid to neutral
Btn (lower part), Btkn, Btng or Btkng horizons:
Hue: 10YR or 2.5Y
Value: 4 to 6
Chroma: 1 to 6
Texture: Silty clay loam or silt loam
Clay content: 20 to 35 percent
Sand content: less than 10 percent
Reaction: Strongly acid to moderately alkaline in the upper part, slightly alkaline to strongly alkaline in the lower part
Some pedons contain carbonates.
BCn, BCng,BCkn, or BCkng horizons where present:
Hue: 10YR or 2.5Y
Value: 4 to 6
Chroma: 1 to 6
Texture: Silty clay loam or silt loam
Clay content: 20 to 30 percent
Sand content: less than 10 percent
Reaction: Slightly alkaline to strongly alkaline
Some pedons contain carbonates.
Cn or Cng horizons where present:
Hue: 10YR, or 2.5Y
Value: 4 to 6
Chroma: 2 to 6
Texture: Silt loam
Clay content: 15 to 27 percent
Sand content: less than 10 percent
Reaction: Slightly alkaline to strongly alkaline
Some pedons contain carbonates.
2BCn, or 2BCng horizons, where present:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 to 6
Chroma: 2 to 6
Texture: Silty clay loam, clay loam, silt loam, or loam
Clay content: 15 to 30 percent
Sand content: 5 to 40 percent
Reaction: Slightly alkaline to strongly alkaline
Rock fragments: 0 to 5 percent
Some pedons contain carbonates.
2Cn, or 2Cng horizons:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 to 6
Chroma: 2 to 6
Texture: Silty clay loam, clay loam, silt loam, or loam
Clay content: 15 to 30 percent
Sand content: 5 to 40 percent
Reaction: Slightly alkaline to strongly alkaline
Rock fragments: 0 to 5 percent
Some pedons contain carbonates.
3C 3Cn, or 3Cng horizons, where present:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 to 6
Chroma: 2 to 6
Texture: Silty clay loam, clay loam, silt loam, or loam
Clay content: 15 to 30 percent
Sand content: 15 to 40 percent
Reaction: Slightly alkaline to strongly alkaline
Rock fragments: 1 to 15 percent
Some pedons contain carbonates.
COMPETING SERIES: There are no other series in this family. Series in closely related families are Coulterville, Darmstadt, Grantfork, and Piasa. Coulterville and Grantfork soils do not have natric horizons. Darmstadt soils average less than 35 percent clay in the particle size control section. Piasa soils have chroma of 2 or less in the upper part of the B horizon.
GEOGRAPHIC SETTING: Tamalco soils are on convex summits and sideslopes of ridges and on sideslopes of drainageways on the loess-covered till plains of the Illinois episode. Slope ranges from 0 to 10 percent. Tamalco soils typically formed in loess. Some pedons formed in loess and the underlying mixed loess and drift. Tamalco soils are underlain, at a depth of 1.0 to 2.0 meters (3.5 to 6.5 feet), by the Farmdale Geosol. The Farmdale soil is underlain by the Sangamon Geosol at depths greater than 200 cm (80 inches). The paleosol may or may not have been truncated by erosion prior to loess deposition. Mean annual air temperature ranges from 12 to 13 degrees C (53 to 56 degrees F), mean annual precipitation ranges from 914 to 1,067 mm (36 to 42 inches), frost-free period is 180 to 200 days, and elevation is 137 meters (450 feet) to 229 meters (750 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cisne, Cowden, Darmstadt, Hoyleton, Huey, Oconee, Piasa, and Richview soils. The poorly drained Cisne, Cowden, Huey, and Piasa soils are on talfs. In addition Cisne and Cowden soils do not have natric horizons. The somewhat poorly drained Darmstadt soils are on talfs, lower broad convex summits, or on similar sideslopes nearby. The somewhat poorly drained Hoyleton and Oconee soils are on talfs, or lower summits, and do not have natric horizons. The moderately well drained Richview soils do not have a natric horizon and are on slightly higher summits nearby.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained. Depth to the top of a perched water table is from 43 to 91 cm (17 to 36 inches) at some time from February to April in normal years. Saturated hydraulic conductivity is moderately high in the surface and subsurface layers, low to moderately low in the upper subsoil, and moderately low in the lower subsoil and underlying material. Permeability is moderate in the surface and subsurface layers, very slow in the upper subsoil, and slow in the lower subsoil and underlying material
USE AND VEGETATION: Most areas of Tamalco soils are cultivated. Corn, soybeans, and small grain are the principal crops. Native vegetation was hardwood trees.
DISTRIBUTION AND EXTENT: Southern Illinois. The series is of moderate extent in MLRAs 113 and 114B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Montgomery County, Illinois, 1968.
REMARKS: The classification of the Tamalco Series was changed from Typic to Aquic in 1/2009 as the aquic subgroup was added to Natrudalfs with the Eighth Edition of Keys to Soil Taxonomy.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - zone from the surface of the soil to a depth of 28 cm (11 inches) (Ap, E, and BE horizons); natric horizon the zone from a depth of 28 to71 cm (11 to 28 inches) (Btn, Btkn horizons).
ADDITIONAL DATA: Data from Pedology Lab at the University of Illinois for the typical pedon was published in the 1969 Soil Survey of Montgomery County, Illinois. The pedon number is 59IL-135-003, and the lab number is 18350-18368. This pedon was re-sampled to update the redoximorphic features and provide horizon information to a depth of 203 cm (80 inches). Additional data from the National Soil Survey Lab and the University of Illinois are on file for several pedons. The typical pedon will be linked to NASIS data mapunit #517398.