LOCATION WEIR IL

Established Series
Rev. JBF-JWS-JCD
03/2011

WEIR SERIES

The Weir series consists of very deep, poorly drained soils formed in loess on nearly level uplands. Slopes range from 0 to 2 percent. Mean annual temperature is about 55 degrees F. (13 degrees C.), and mean annual precipitation is about 42 inches (1067 mm).

TAXONOMIC CLASS: Fine, smectitic, mesic Typic Endoaqualfs

TYPICAL PEDON: Weir silt loam - nearly level in a cultivated field at an elevation of about 495 feet (151 meters) above mean sea level. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 8 inches (0 to 20 cm); dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; weak fine granular structure; friable; moderately acid; abrupt smooth boundary. {5 to 10 inches (13 to 25 cm) thick]

Eg--8 to 17 inches (20 to 43 cm); light brownish gray (10YR 6/2) silt loam; weak thin platy structure; friable; few medium distinct light yellowish brown (10YR 6/4) masses of oxidized iron in the matrix; very strongly acid; clear smooth boundary. [7 to 15 inches (18 to 38 cm) thick]

Btg1--17 to 21 inches (43 to 53 cm); gray (10YR 5/1) silty clay loam; weak medium prismatic structure parting to moderate medium angular blocky; firm; common distinct grayish brown (10YR 5/2) clay films on faces of peds; common medium distinct brown (10YR 5/3) and yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; very strongly acid; clear smooth boundary.

Btg2--21 to 30 inches (53 to 76 cm); gray (10YR 5/1) silty clay loam; moderate medium prismatic structure parting to moderate medium angular blocky; firm; common distinct grayish brown (10YR 5/2) clay films on faces of peds; many medium distinct yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; very strongly acid; gradual smooth boundary.

Btg3--30 to 39 inches (76 to 99 cm); gray (10YR 5/1) silty clay loam; moderate medium subangular blocky structure; firm; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds; many medium distinct yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; very strongly acid; gradual smooth boundary. [Combined thickness of the Btg horizon is 20 to 45 inches (51 to 114 cm).]

BCg--39 to 46 inches (99 to 117 cm); gray (10YR 6/1) silt loam; weak coarse subangular blocky structure; firm; few faint dark grayish brown (10YR 4/2) clay films on faces of peds; many medium distinct yellowish brown (10YR 5/4) masses of oxidized iron in the matrix; strongly acid; gradual smooth boundary. [0 to 21 inches (0 to 53 cm) thick]

Cg--46 to 60 inches (117 to 152 cm); light brownish gray (10YR 6/2) silt loam; massive; friable; many medium prominent yellowish brown (10YR 5/6) masses of oxidized iron in the matrix; moderately acid.

TYPE LOCATION: Lawrence County, Illinois; about 2 miles west of Lawrenceville; 200 feet south and 50 feet east of the northwest corner of sec. 2, T. 3 N., R. 12 W.; USGS Lawrenceville topographic quadrangle; lat. 38 degrees 43 minutes 53 seconds N., and long. 87 degrees 43 minutes 18 seconds W.; UTM Zone 16S 0437271E 4287222N; NAD 83.

RANGE IN CHARACTERISTICS:
Depth to the base of the argillic horizon: 35 to more than 60 inches (89 to >152 cm)
Particle-size control section: averages between 35 and 40 percent clay; Individual subhorizons contain as much as 45 percent clay.
Series control section: less than 10 percent fine sand or coarser
Mean annual soil temperature: 55 to 59 degrees F. (13 to 15 degrees C.).

Ap or A horizon:
Hue: 10YR
Value: 4 or 5
Chroma: 1 or 2
Reaction: very strongly acid to moderately acid, except pedons that have been limed include slightly acid or neutral

Eg horizon:
Hue: 10YR or 2.5Y
Value: 5 to 7
Chroma: 2
Reaction: very strongly acid to moderately acid except pedons that have been limed include slightly acid or neutral.

Some pedons have a BE horizon.

Btg or BCg horizon:
Hue: 10YR, 2.5Y or 5Y
Value: 4 to 6,
Chroma: 1 or 2
Texture: Btg horizon is typically silty clay loam, but includes subhorizons of silty clay in some pedons and the BCg horizon, where present, is silt loam or silty clay loam
Clay content: 20 to 30 percent
Reaction is extremely acid to moderately acid in the Btg horizon and very strongly acid or strongly acid in the BCg horizon

Cg horizon:
Hue: 10YR, 2.5Y, 5Y, or is neutral
Value: 4 to 6
Chroma: 0 to 2
Texture: silt loam.
Clay content: 20 to 26 percent
Reaction: very strongly acid to slightly acid to a depth of 60 inches (152 cm) or more

COMPETING SERIES: These are the Concord, Elbert, Kampville, Sexton, and Traer series. The Concord soils have a mean annual soil temperature (MAST) of less than 55 degrees F. and average more than 40 percent clay in the particle-size control section. Elbert soils have a paralithic contact at depths of 40 to 60 inches (102 to 152 cm). Kampville soils have 27 percent or more clay in the Cg horizon. Sexton soils have more than 10 percent sand in the lower part of the series control section. The Traer soils have a mean annual soil temperature (MAST) of less than 55 degrees F. and typically have carbonates in the Cg horizon.

GEOGRAPHIC SETTING: Weir soils are on upland divides that have a planar or concave surface. Slopes range from 0 to 2 percent. The soils formed in loess. Mean annual air temperature ranges from 54 to 57 degrees F. (12 to 14 degress C.), mean annual precipitation ranges from 35 to 48 inches (890 to 1219 mm), frost free period ranges from 170 to 200 days, and elevation ranges from 340 to 1,020 feet (104 to 311 meters) above sea level.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hosmer, Marine, and Stoy soils. The moderately well drained Hosmer soils and the somewhat poorly drained Stoy soils are fine-silty. They are nearby on similar or more sloping parts of the landscape and form a drainage sequence with Weir soils. The somewhat poorly drained Marine soils have an abrupt textural change from the E horizon to the Bt horizon. They are on similar parts of the landscape nearby.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. An intermittent perched seasonal high water table is within 1 foot (30 cm) of the surface at some time between January and June in normal years. This soil is subject to periods of occasional, very brief ponding at depths up to 15 cm (0.5 foot) from January to June in normal years. The potential for surface water runoff is high. Saturated hydraulic conductivity is low or moderately low (0.07 to 0.42 micrometers/sec) in the slowest layer. Permeability is very slow (0.01 to 0.06 inches per hour).

USE AND VEGETATION: Most areas are cropped. Corn and soybeans are the principal crops. Native vegetation is deciduous forest.

DISTRIBUTION AND EXTENT: Southern Illinois and Missouri. The extent is moderate in MLRAs 113, 114B, 115A, 115B and 120A.

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

SERIES ESTABLISHED: Lawrence County, Illinois, 1952.

REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 17 inches (43 cm) [Ap and Eg horizons];
albic horizon - the zone from approximately 8 to 17 inches (20 to 43 cm) [Eg horizon];
argillic horizon - the zone from approximately 17 to 39 inches (43 to 99 cm) [Btg1, Btg2, and Btg3 horizons].

National Cooperative Soil Survey
U.S.A.