LOCATION PLANO IL+IN WI IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Argiudolls
TYPICAL PEDON: Plano silt loam on a nearly level slope in a cultivated field at an elevation of about 218 meters (715 feet)above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 23 cm (0 to 9 inches); very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; friable; few very fine roots; slightly acid; clear smooth boundary.
A--23 to 36 cm (9 to 14 inches); dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine granular structure; friable; many very fine roots; slightly acid; clear smooth boundary. [Combined thickness of the A horizons is 25 to 51 cm (10 to 20 inches)]
Bt1--36 to 48 cm (14 to 19 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate fine subangular blocky structure; friable; common very fine roots; many distinct dark brown (10YR 3/3) organo-clay films on faces of peds; slightly acid; clear smooth boundary.
Bt2--48 to 79 cm (19 to 31 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; friable; common very fine roots; many distinct brown (10YR 4/3) clay films on faces of peds; slightly acid; clear smooth boundary.
Bt3--79 to 109 cm (31 to 43 inches); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium prismatic structure parting to moderate medium subangular blocky; friable; few very fine roots; many distinct brown (10YR 4/3) clay films on faces of peds; common distinct very pale brown (10YR 7/3) (dry) silt coatings on faces of peds; few fine faint yellowish brown (10YR 5/4) iron-manganese accumulations in the matrix; slightly acid; clear smooth boundary.
Bt4--109 to 124 cm (43 to 49 inches); dark yellowish brown (10YR 4/4) silt loam; moderate medium prismatic structure; friable; few very fine roots; many distinct brown (10YR 4/3) clay films on faces of peds; few distinct very pale brown (10YR 7/3) (dry) silt coatings on faces of peds; slightly acid; clear smooth boundary. [Combined thickness of the Bt horizons is 51 to 89 cm (20 to 35 inches)]
2Bt5--124 to 135 cm (49 to 53 inches); dark yellowish brown (10YR 4/4) clay loam; weak medium prismatic structure; friable; few fine roots; many distinct brown (10YR 4/3) clay films on faces of peds; neutral; clear smooth boundary. [15 to 51 cm (6 to 20 inches) thick]
2BC--135 to 152 cm (53 to 60 inches); brown (7.5YR 4/4) sandy loam; weak medium subangular blocky structure; very friable; many distinct dark yellowish brown (10YR 3/4) clay bridging between sand grains; 5 percent gravel; neutral; gradual smooth boundary. [0 to 25 cm (0 to 10 inches) thick]
2C--152 to 183 cm (60 to 72 inches); stratified yellowish brown (10YR 5/6) and brown (7.5YR 4/4) sandy loam, loam, and loamy sand; massive; friable; 12 percent gravel; neutral.
TYPE LOCATION: Stark County, Illinois; Valley township; 1,200 feet south and 1,920 feet east of the northwest corner of sec. 13, T. 12 N., R. 7 E.; USGS Castleton, IL topographic quadrangle; lat. 41 degrees, 01 minute, 45 seconds, N. and long. 89 degrees, 39 minutes, 00 seconds W.; NAD 27; UTM Zone 16, easting 0277210, northing 4545382, NAD 83.
RANGE IN CHARACTERISTICS: The depth to the base of the argillic horizon ranges from 112 to 178 cm (44 to 70 inches). The depth to horizons with more than 10 percent sand ranges from 102 to 152 cm (40 to 60 inches). These soils do not have carbonates in the solum. The mollic epipedon is 25 to 51 cm (10 to 20 inches) in thickness. The particle-size control section averages 27 to 35 percent clay and less than 10 percent sand.
The Ap or A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 to 3 moist or dry. Clay content ranges from 18 to 27 percent. It is slightly acid or neutral.
The AB or BA horizon, where present, has hue of 10YR, value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 to 4 moist or dry. It is silt loam or silty clay loam. It is moderately acid to neutral.
The upper part of the Bt horizon has hue of 10YR, value of 4 or 5 and chroma of 3 or 4. Clay content ranges from 20 and 35 percent. It typically is moderately acid but ranges from strongly acid to neutral.
The lower part of the Bt horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 2 to 4. Some pedons have iron depletions or clay films with chroma of 1 or 2. Average clay content ranges from 25 to 30 percent. Individual subhorizons range from 20 to 33 percent clay. It is moderately acid to neutral.
The 2Bt or 2BC horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 2 to 6. It is silt loam, loam, sandy loam, clay loam, or sandy clay loam. Average clay content ranges from 15 to 32 percent and average sand content range from 20 to 60 percent. Volume of coarse fragments averages between 2 to 15 percent. Individual subhorizons or strata range from 5 to 35 percent clay, 20 to 90 percent sand, and from 2 to 25 percent gravel. It ranges from moderately acid to slightly alkaline.
The 2C horizon is in the lower part of the series control section in some pedons. It has hue of 7.5YR, 10YR, or 2.5Y, value to 3 to 5, and chroma of 3 to 6. Some pedons have redoximorphic features with value of 5 or 6 and chroma of 2 to 6. It is loam, loamy sand, sandy loam, or silt loam, and typically is stratified. Average clay content ranges from 5 to 20 percent and average sand content ranges from 25 to 80 percent. Volume of coarse fragments averages between 3 to 25 percent. It is moderately acid to moderately alkaline.
COMPETING SERIES: These are the Ashdale, Broadwell, Dinsdale, Douglas, Elkhart, Elmont, Healing, Lycurgus, Malcolm, Meadowbank, Mendota, Mickle, Ogle, Osco, Parkway, Proctor, Richwood, Ripon, Sibley, Sidell, Tama, Tecumseh, Toddville, Wakenda, Waupecan, and Wiota series. Ashdale, Elmont, and Ripon soils have sola terminated by bedrock within a depth of 152 cm (60 inches). Broadwell, Richwood, and Toddville soils have in the lowest one-quarter of the series control section an average sand content of greater than 80 percent. Dinsdale, Lycurgus, Meadowbank, Mendota, Proctor, Sidell, Tecumseh, and Waupecan soils have horizons with more than 10 percent sand within a depth of 102 cm (40 inches). Douglas and Parkway soils have in the lowest one-quarter of the series control section a narrower range in sand content with no subhorizon exceeding 45 percent sand nor exceeding 15 percent gravel. Elkhart, Osco, Tama, Wakenda, and Wiota soils have in the lowest one-quarter of the series control section an average sand content of less than 25 percent. Healing soils average more than 1 percent coarse fragments of chert in the upper part of the series control section. Malcolm soils have the base of the argillic horizon within a depth of 112 cm (44 inches). Mickle soils average 18 to 30 percent clay in the particle-size control section. Ogle soils have hue of 5YR or redder in the lower part of the series control section. Sibley soils have mollic epipedons greater than 51 cm (20 inches) thick.
GEOGRAPHIC SETTING: Plano soils are on outwash plains or stream terraces. Slope gradients commonly are 0 to 5 percent but some are as steep as 12 percent. The soils formed in 102 to 152 cm (40 to 60 inches) of loess or other silty material and the underlying loamy stratified outwash or sandy loam till. The mean annual air temperature ranges from 8 to 12 degrees C (46 to 54 degrees F), mean annual precipitation ranges from 740 to 990 mm (29 to 39 inches), frost-free period ranges from 160 to 180 days, and elevation ranges from 207 to 311 meters (680 to 1020 feet) above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Proctor soils and the Brenton, Catlin, Dana, Drummer, Elburn, and Thorp soils. The moderately well drained Catlin and Dana soils are on adjacent moraines. Proctor soils are on similar nearby parts of the landscape where the mantle of loess is thinner. The somewhat poorly drained Brenton and Elburn soils and the poorly drained Drummer and Thorp soils are on lower parts of the landscape. Elburn and Drummer soils form a drainage sequence with Plano soils in areas underlain by loamy outwash.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Plano soils are well drained. The potential for surface runoff is low or medium. Saturated hydraulic conductivity is 4.23 to 14.11 micrometers per second (moderate permeability) in the solum and 4.23 to 42.34 micrometers per second (moderate to moderately rapid permeability) in the underlying material. Very rarely flooded or rarely flooded phases of these soils that occur on stream terraces are recognized.
USE AND VEGETATION: Most areas of Plano soils are cultivated. Corn and soybeans are the principal crops. Native vegetation is prairie grasses.
DISTRIBUTION AND EXTENT: Illinois, Wisconsin, Iowa, and Indiana. LRRs K and M, MLRAs 95B, 104, 108A, 108B, 108C, 110, and 115C. The extent is large; more than 426,000 acres have been correlated to date, the majority of which is in MLRA 108.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Kendall County, Illinois, 1941.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
mollic epipedon -- from the a depth of 0 to 36 cm (0 to 14 inches) (Ap and A horizons)
argillic horizon -- from 36 to 135 cm (14 to 53 inches) (Bt1, Bt2, Bt3, Bt4, and 2Bt5 horizons)
lithologic discontinuity from loess to outwash at a depth of 124 cm (49 inches)