LOCATION VIRDEN IL+MOEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Argiaquolls
TYPICAL PEDON: Virden silty clay loam - in a nearly level cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 20 cm (0 to 8 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate medium granular structure; firm; slightly alkaline; abrupt smooth boundary.
A--20 to 41 cm (8 to 16 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine granular structure; firm; moderately acid; clear smooth boundary. [Combined thickness of the A horizons is 20 to 51 cm (10 to 20 inches).]
Btg1--41 to 58 cm (16 to 23 inches); very dark gray (10YR 3/1) silty clay, grayish brown (10YR 5/2) dry; strong fine angular blocky structure; firm; few faint black (10YR 2/1) organo-clay films on faces of peds; few fine faint black (10YR 2/1) manganese concretions throughout; slightly acid; clear smooth boundary.
Btg2--58 to 86 cm (23 to 34 inches); gray (5Y 5/1) silty clay loam; weak coarse prismatic structure parting to moderate medium angular blocky; firm; few distinct dark gray (10YR 4/1) clay films on faces of peds; many medium prominent brownish yellow (10YR 6/6) masses of iron accumulation and few fine prominent black (10YR 2/1) masses of manganese accumulation throughout; slightly acid; clear smooth boundary.
Btg3--86 to 107 cm (34 to 42 inches); gray (5Y 5/1) silty clay loam; weak and moderate coarse prismatic structure parting to moderate coarse angular blocky; firm; few distinct dark gray (5Y 4/1) clay films on faces of peds; common medium prominent light olive brown (2.5Y 5/6) masses of iron accumulation and few fine prominent black (10YR 2/1) masses of manganese accumulation throughout; neutral; clear smooth boundary.
Btg4--107 to 124 cm (42 to 49 inches); gray (5Y 5/1) silty clay loam; moderate coarse prismatic structure parting to weak coarse angular blocky; firm; very few distinct dark gray (N 4/0) clay films on faces of peds; many medium prominent olive brown (2.5Y 4/4) masses of iron and manganese accumulation throughout; neutral; gradual smooth boundary. [Combined thickness of the Btg horizons is 36 to 114 cm (14 to 45 inches).]
Cg--124 to 152 cm (49 to 60 inches); gray (5Y 5/1) silty clay loam; massive; firm; common medium prominent olive brown (2.5Y 4/4) masses of iron and manganese accumulation throughout; neutral.
TYPE LOCATION: Adams County, Illinois; 140 feet west and 54 feet north of the southeast corner of the sec. 3, T. 2 N., R. 6 W.; at an elevation of 699 feet; USGS Bowen, IL topographic quadrangle; lat. 40 degrees 10 minutes 49 seconds N. and long. 91 degrees 4 minutes 0 seconds W. or UTM zone15 664587E 4449564N, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 102 to 152 cm (40 to 60 inches). The mollic epipedon is 25 to 61 cm (10 to 24 inches) in thickness and commonly extends into the upper part of the B horizon. Depth to free carbonates ranges from 127 to 203 cm (50 to 80 inches). The particle size control section averages between 35 and 40 percent clay. The series control section averages 0 to 5 percent sand and 0 to 1 percent rock fragments. The soils are dry in all parts of the soil moisture control section for less than 30 of the 120 days following the summer solstice.
The Ap and A horizons have hue of 10YR, value of 2 or 3, and chroma of 1 or 2. Many pedons have redox features in the lower subhorizons. Texture is silty clay loam or silt loam. Average clay content 25 to 30 percent. Individual subhorizons can have from 20 to 33 percent clay.
Some pedons have an AB or BA horizon.
The Btg horizon has hue of 10YR, 2.5Y, 5Y or is neutral, value of 2 to 6, and chroma dominantly of 0 to 2 and ranging to 4. Clay films have value of 2 to 5 and chroma of 0 to 2. The B/A clay ratio is between 1.2 and 1.4. The texture is silty clay loam, silty clay, or silt loam. Clay content ranges form 25 to 42 percent clay in individual subhorizons. Reaction ranges from moderately acid to neutral.
Some pedons have BCg horizon.
The Cg horizon has hue of 10YR, 2.5Y, 5Y, or is neutral, value of 4 to 6, and chroma dominantly of 0 to 2 and ranging to 4. It is silty clay loam or silt loam. Clay content ranges from 20 to 32 percent. Reaction ranges from slightly acid to moderately alkaline.
COMPETING SERIES: These are the Butler, Carbika, Chancellor, Clarinda, Coatsburg, Edinburg, Fosterburg, Haig, Lodgepole, Mazaska, Minnetonka, Sacville, Sampsel, Taintor, Terrabella, and Worthing series. Butler, Clarinda, Haig, Minnetonka, and Terrabella soils average more than 40 percent clay in the particle size control section. Carbika, Coatsburg and Lodgepole soils average more than 5 percent sand in the control section. Chancellor and Worthing soils have a mollic epipedon more than 61 centimeters (24 inches) in thickness. Edinburg soils have an albic horizon or noticeable clean silt grains in some subhorizon in the upper one-half of the control section. Fosterburg soils have a concentration of exchangeable sodium in the argillic horizon. Mazaska soils average more than 10 percent sand in the bottom one-forth of the control section. Sacville soils have gravel in the middle and lower parts of the series control section. Sampsel soils have a paralithic contact in the lower part of the series control section. Tainter and Worthing soils average less than 12 degrees C. (54 degrees F.) in the temperature control section.
GEOGRAPHIC SETTING: Virden soils are on nearly level summits on loess covered Illinoian till plain. Slopes commonly are less than 1 percent, but range from 0 to 2 percent. The Virden soils formed in loess. The mean annual air temperature ranges from 11.7 to 13.9 C. (53 to 57 degrees F.); mean annual precipitation ranges from 864 to 1143 mm (34 to 45 inches); frost free days range from 170 to 200 days; and elevation ranges from 104 to 244 meters (340 to 800 feet) above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cowden, Denny, Harrison, Herrick, Ipava, Oconee and Piasa soils. Cowden and Oconee soils do not have mollic epipedons and have albic horizons. Cowden soils are on similar nearby nearly level summits and Oconee soils are nearby on low convex ridges or along drainageways. The moderately well drained Harrison soils and the somewhat poorly drained Herrick and Ipava soils are on convex ridges or along the dissecting drainageways and form a hydrosequence with Virden soils. Piasa soils have a natric horizon and an albic horizon and are on nearly level summits nearby.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. Potential for surface runoff is negligible to low. Saturated hydraulic conductivity is 1.41 to 4.23 micrometers per second in the subsoil and substratum. Permeability is moderately slow. In undisturbed areas there is an apparent seasonal high water table within a depth of 30 centimeters (1.0 foot) during November to May in normal years. Some areas are subject to ponding.
USE AND VEGETATION: Most areas are cropped. Corn, soybeans, and small grain are the principal crops. Native vegetation is wetland prairie grasses and sedges.
DISTRIBUTION AND EXTENT: West-central and southern Illinois. Virden soils are extensive in MLRA's 108B, 114B, 115B and 115C.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Christian County, Illinois, 1948.
REMARKS: A new typical pedon is added with this update (10/2006). The new pedon has a silty clay loam surface layer which is the dominant surface texture for the series.
Diagnostic horizons and features recognized in this pedon are:
mollic epipedon - the zone from the surface of the soil to a depth of 58 centimeters (23 inches) - Ap, A, and Btg1 horizons;
argillic horizon - the zone from 41 to 124 centimeters (16 to 49 inches) - Btg1, Btg2, Btg3, and Btg4 horizons
ADDITIONAL DATA: Data from the pedology laboratory, University of Illinois, for several pedons are on file at the Illinois state office. Engineering test data from the Illinois Department of Transportation for several pedons are also on file at the Illinois state office.