LOCATION TIMEWELL ILEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aquic Argiudolls
TYPICAL PEDON: Timewell silt loam - nearly level, in a cultivated field at an elevation of about 750 feet above sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; friable; few fine roots; neutral; abrupt smooth boundary.
A--8 to 12 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak medium platy structure parting to moderate fine granular; friable; few fine roots; neutral; abrupt smooth boundary. (Combined
thickness of the Ap or A horizons is 10 to 15 inches.)
AE--12 to 18 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate thin platy structure parting to weak fine granular; friable; few fine roots; common fine irregular distinct light gray (10YR 7/1) clay depletions throughout and few fine irregular prominent yellowish brown (10YR 5/8) masses of iron accumulation throughout and few fine rounded distinct black (7.5YR 2/1) masses of iron and manganese accumulation throughout; moderately acid; clear smooth boundary. (3 to 6 inches thick)
Bt1--18 to 22 inches; yellowish brown (10YR 5/4) silty clay loam; moderate fine subangular blocky structure; firm; few fine roots; many distinct continuous very dark gray (10YR 3/1) organo-clay films on faces of peds; few fine irregular distinct yellowish brown (10YR 5/8) masses of iron accumulation throughout and few fine irregular distinct grayish brown (10YR 5/2) iron depletions throughout and common fine rounded distinct black (7.5YR 2/1) masses of iron and manganese accumulation throughout; strongly acid; clear smooth boundary.
Bt2--22 to 29 inches; yellowish brown (10YR 5/4) silty clay; weak medium prismatic structure parting to moderate fine subangular blocky; firm; few fine roots; many distinct continuous very dark gray (10YR 3/1) organo-clay films on faces of peds; many fine irregular distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout and few fine irregular distinct grayish brown (10YR 5/2) iron depletions throughout and common fine rounded distinct black (7.5YR 2/1) masses of iron and manganese accumulation throughout; strongly acid; clear smooth boundary.
Btg1--29 to 40 inches; grayish brown (2.5Y 5/2) silty clay; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; few fine roots; many distinct continuous very dark gray (10YR 3/1) organo-clay films on faces of peds and in pores; common fine irregular distinct yellowish brown (10YR 5/4) masses of iron accumulation throughout and common fine irregular prominent strong brown (7.5YR 5/6) masses of iron accumulation throughout and common fine and medium rounded prominent black (7.5YR 2/1) masses of iron and manganese accumulation throughout; moderately acid; clear smooth boundary.
Btg2--40 to 48 inches; light brownish gray (2.5Y 6/2) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; few fine roots; common distinct continuous dark gray (10YR 4/1) clay films on faces of peds and common distinct continuous very dark gray (10YR 3/1) organic coats in root channels and/or pores; many medium irregular distinct yellowish brown (10YR 5/4) masses of iron accumulation throughout and common medium irregular prominent yellowish brown (10YR 5/8) masses of iron accumulation throughout and common prominent fine and medium rounded black (7.5YR 2/1) masses of iron and manganese accumulation throughout; moderately acid; clear smooth boundary.
Btg3--48 to 56 inches; light brownish gray (2.5Y 6/2) silty clay loam; weak medium prismatic structure parting to weak medium subangular blocky; friable; few fine roots; common distinct continuous dark gray (10YR 4/1) clay films on faces of peds and few distinct continuous very dark gray (10YR 3/1) organic coats in root channels and/or pores; few fine irregular distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout and common fine irregular prominent light yellowish brown (10YR 6/4) masses of iron accumulation throughout and few fine rounded prominent black (7.5YR 2/1) masses of iron and manganese accumulation throughout; moderately acid; clear smooth boundary. (Combined thickness of the Bt horizons is 20 to 40 inches.)
BCtg--56 to 67 inches; light brownish gray (2.5Y 6/2) silt loam; weak medium prismatic structure; friable; few fine roots; few distinct discontinuous dark gray (10YR 4/1) clay films on faces of peds and few distinct discontinuous very dark gray (10YR 3/1) organic coats in root channels and/or pores; many fine irregular distinct yellowish brown (10YR 5/6) masses of iron accumulation throughout and common fine irregular distinct light yellowish brown (10YR 6/4) masses of iron accumulation throughout and few fine rounded prominent black (7.5YR 2/1) masses of iron and manganese accumulation throughout; moderately acid; clear smooth boundary. (0 to 20 inches thick)
Cg--67 to 80 inches; light gray (5Y 7/1) silt loam; massive; friable; very few distinct discontinuous very dark gray (10YR 3/1) organic coats in root channels and/or pores; many medium irregular prominent yellowish brown (10YR 5/6) masses of iron accumulation throughout and few fine rounded prominent black (7.5YR 2/1) masses of iron and manganese accumulation throughout; neutral.
TYPE LOCATION: Brown County, Illinois; about 2 miles southwest of Mound Station; 271 feet north and 1808 feet east of the southwest corner of sec. 7, T. 1 S., R. 4 W.; USGS Kellerville, IL. topographic quadrangle; Latitude 39 degrees 59 minutes 20 seconds N., and Longitude 90 degrees 54 minutes 20 seconds W.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 45 to 70 inches. The mollic epipedon ranges from 10 to 21 inches in thickness and includes the AE or E horizon in some pedons. All horizons have base saturation greater than 50 percent. Free carbonates are not present within a depth of 60 inches. The series control section has sand content less than 8 percent and rock fragment content less than 1 percent. The particle- size control section averages between 35 and 42 percent clay.
The upper part of the control section (Ap, A, E, or AE horizons) has clay content of 18 to 27 percent. Reaction is strongly acid to neutral. Individual horizons have properties as follows:
The Ap or A horizon has value of 2 or 3 (4 or 5 dry) and chroma of 1 or 2. It is silt loam.
The E or AE horizon ranges from distinct to incipient. It has value of 3 or 4 (5 or 6 dry), and chroma of 1 or 2. Clay depletions have value of 5 or 7, and chroma of 1 or 2. Some pedons have faint redoximorphic iron and manganese accumulations with value of 3 to 6 and chroma of 3 to 8.
The middle part of the control section (B horizon) has average clay content of 35 to 38 percent. Individual subhorizons have between 25 and 45 percent clay. Reaction ranges from very strongly acid in the upper horizons to neutral in the lower horizons. Other properties by horizon are as follows:
The B horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 2 to 6. Hue of 5Y, if present, is in the lower part. Redoximorphic iron and manganese accumulations and depletions have hue of 7.5YR, 10YR, or 2.5Y, value of 2 to 6, and chroma of 1 to 8. The Bt horizon is silty clay loam or silty clay in the upper part, and silty clay loam or silt loam in the lower part.
The lower part of the control section (C horizon) has hue of 10YR, 2.5Y, or 5Y; value of 4 to 7; and chroma of 1 to 6. Redoximorphic iron and manganese accumulations and depletions have colors similar to the range described in the B horizon. It is silt loam or, less commonly, silty clay loam. Clay content ranges from 20 to 30 percent. Reaction ranges from moderately acid to neutral.
COMPETING SERIES: These are the Adair, Arisburg, Arispe, Biddle, Chase, Flanagan, Greenton, Grundy, Herrick, Ipava, Lagonda, Lamoni, Mahaska, Martin, Mayberry, Pawnee, Rutland, Seymour, Shorewood, Tina, and Wymore soils. Adair, Flanagan, Lagonda, Lamoni, Pawnee, Shorewood, and Tina soils have more than 8 percent sand in the lower part of the control section. Arisburg and Herrick soils have a mean annual soil temperature more than 56 degrees F. Arispe soils have the maximum content of clay at depths less than 20 inches. Biddle soils have 5 to 15 percent exchangeable sodium in the subsoil. Chase and Martin soils have mollic epipedons greater than 24 inches thick. Greenton and Rutland soils average more than 30 percent clay in the lower part of the control section. Grundy, Seymour, and Wymore soils average more than 42 percent clay in the particle-size control section. Ipava and Mahaska soils do not have an AE or E horizon or a moist color value more than 3 in the upper part of the control section. Mayberry soils have hue redder than 10YR in the middle part of the series control section.
GEOGRAPHIC SETTING: Timewell soils are on summits and sideslopes on till plains. Slope gradients range from 0 to 5 percent. They formed in 5 to more than 20 feet of loess. Mean annual air temperature ranges from 50 to 54 degrees F., mean annual soil temperature ranges from 52 to 56 degrees F., mean annual precipitation ranges from 34 to 40 inches, frost free days range from 160 to 190 days, and elevation ranges from 350 to 1020 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Clarksdale, Ipava, Newvienna, Osco, Rubio, and Virden soils. Clarksdale soils have a thinner dark surface soil, and are closer to dissecting drainageways. Ipava soils are on similar landform positions, and do not have an E horizon. Osco and Newvienna soils average less clay in the particle-size control section, are moderately well drained, and are on similar and more sloping landform positions. Rubio and Virden soils are poorly drained, and on slightly lower to depressional landform positions. In addition, Rubio soils have a thinner dark surface soil, and Virden soils do not have an E horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Surface runoff is slow. Permeability is moderately slow. The seasonal high water table is at a depth of 1.0 to 2.0 feet below the surface in the spring.
USE AND VEGETATION: These soils are mostly cultivated. Corn and soybeans are the dominant crops. Small acreages are used for small grains and meadow.
DISTRIBUTION AND EXTENT: Western Illinois. Extent is moderate, and mainly in MLRA 115C.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES PROPOSED: Brown County, Illinois, 1997. The Timewell series was named for the northwestern extent of the Herrick series.
REMARKS: Timewell soils were formerly included with the Herrick series. Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 18 inches (Ap, A, and AE horizons); argillic horizon - zone from approximately 18 to 67 inches (Bt1, Bt2, Btg1, Btg2, Btg3, and BCtg horizons). Udic moisture regime.
ADDITIONAL DATA: Particle size data are on file for pedons of the Timewell soils, at the NRCS MLRA Office Region 11.