The Buckhart series consists of very deep, moderately well drained soils formed
in loess on ground moraines. Permeability is moderate. Slope ranges from 0 to 5
percent. Mean annual precipitation is about 36 inches and mean annual air
temperature is about 52 degrees F.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Argiudolls
TYPICAL PEDON: Buckhart silt loam, 2 to 5 percent slopes, on a south-facing slope in a cultivated field at an elevation of about 603 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; moderate medium granular structure; friable; few very fine roots; moderately acid; clear smooth boundary.
A--8 to 15 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine subangular blocky structure parting to moderate medium granular; friable; few very fine roots; moderately acid; clear smooth boundary. (Combined thickness of the A horizons is 10 to 20 inches)
Bt1--15 to 26 inches; dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure parting to moderate medium granular; friable; few very fine roots; many distinct brown (10YR 4/3) clay films on faces of peds and few distinct very dark grayish brown (10YR 3/2) organic coatings in root channels and/or pores; slightly acid; clear smooth boundary.
Bt2--26 to 37 inches; dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; friable; few very fine roots; many distinct dark grayish brown (10YR 4/2) clay films on faces of peds; few fine irregular prominent strong brown (7.5YR 5/6) masses of iron and manganese accumulations along pores and few fine irregular prominent light brownish gray (2.5Y 6/2) iron depletions along pores; neutral; clear smooth boundary.
Bt3--37 to 52 inches; brown (10YR 5/3) silt loam; weak medium subangular blocky structure; friable; few very fine roots; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds; common fine irregular prominent strong brown (7.5YR 5/6) masses of iron and manganese accumulations along pores and few fine rounded prominent black (7.5YR 2/1) iron-manganese nodules throughout and common fine distinct irregular light brownish gray (2.5Y 6/2) iron depletions along pores; slightly acid; clear smooth boundary. (Combined thickness of the Bt horizons is 25 to 40 inches)
BCt--52 to 67 inches; light olive brown (2.5Y 5/3) silt loam; weak coarse subangular blocky structure; friable; few very fine roots; few distinct dark grayish brown (10YR 4/2) clay films in root channels and/or pores; common fine irregular prominent strong brown (7.5YR 5/6) masses of iron and manganese accumulations along pores and common fine irregular light brownish gray (2.5Y 6/2) iron depletions along pores and few fine rounded prominent black (7.5YR 2/1) iron-manganese nodules throughout; neutral; gradual smooth boundary. (5 to 20 inches thick)
C--67 to 80 inches; yellowish brown (10YR 5/4) silt loam; massive; friable; common medium irregular distinct strong brown (7.5YR 5/6) masses of iron and manganese accumulations throughout and common medium irregular prominent light brownish gray (2.5Y 6/2) iron depletions throughout and few fine rounded prominent black (7.5YR 2/1) iron-manganese nodules throughout; neutral.
TYPE LOCATION: Christian County, Illinois, approximately 360 feet west and 540 feet north of the southeast corner of sec. 24, T. 14 N., R. 3 W.; USGS GROVE CITY, IL. topographic quadrangle; lat. 39 degrees 33 minutes 53 seconds N. and long. 89 degrees 22 minutes 6 seconds W; NAD 27, zone 16.
RANGE IN CHARACTERISTICS: Depth to the base of the argillic horizon ranges from 40 to 55 inches. Loess is greater than 80 inches thick. The mollic epipedon ranges from 10 to 20 inches thick. The particle-size control section averages 27 to 35 percent clay. Sand content is less than 7 percent throughout the series control section. Redoximorphic depletions with chroma of 2 or less are not present in the 6 inches immediately below the mollic epipedon. Carbonates, where present, are below a depth of 40 inches. The mean annual soil temperature is 52 to 56 degrees F.
The Ap and A horizons have hue of 10YR, value of 2 or 3 (4 or 5 dry), and chroma of 1 to 3. It is silt loam or silty clay loam. Average clay content ranges from 20 to 30 percent. Reaction is moderately acid to neutral. Some pedons have an AB or a BA horizon, with a hue of 10YR, value 3 or 4 (4 through 6 dry) and chroma of 2 through 4.
The Bt or Btg horizons have hue of 10YR, or 2.5Y; value of 4 to 6; and chroma of 3 to 6 (2 to 6 in the lower part). Redoximorphic features have hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 6; and chroma of 2 to 8. Texture is dominantly silty clay loam, but has subhorizons of silt loam. Average clay content ranges from 27 to 35 percent. Reaction is moderately acid to neutral.
The BC or BCg horizons have hue of 10YR, or 2.5Y; value of 5 or 6; and chroma of 2 to 4. Redoximorphic features have hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 6; and chroma of 2 to 8. Texture is dominantly silt loam, but is silty clay loam in some pedons. Average clay content ranges from 18 to 30 percent. Reaction is neutral to slightly alkaline.
The C or Cg horizons have hue of 10YR, or 2.5Y; value of 5 or 6; and chroma of 2 to 6. Redoximorphic features have hue of 7.5YR, 10YR, or 2.5Y; value of 4 to 6; and chroma of 2 to 8. Average clay content ranges from 18 to 27 percent. Reaction is neutral to moderately alkaline.
COMPETING SERIES: These are the Assumption, Aviston, Barrington, Blackberry, Catlin, Clare, Dana, Danabrook, Geryune, Graymont, Harrison, Keltner, Saybrook, and Totanang (T) series. Assumption, Clare, Dana, Danabrook, Geryune, and Graymont soils have subhorizons with more than 7 percent sand within a depth of 40 inches. Aviston soils formed in 60 to 80 inches of loess and have a mean annual soil temperature greater than 56 degrees F. Barrington and Saybrook soils have more than 7 percent sand and carbonates within a depth of 40 inches. In addition, the base of the argillic horizon is at depths less than 40 inches in the Saybrook soils. Blackberry, Catlin and Harrison soils have more than 7 percent sand within depths of 60 inches. Keltner soils have a paralithic contact at depths of 40 to 60 inches. Totanang (T) soils have more than 7 percent sand below depths of 24 inches and more than 15 percent rock fragments in the lower part of the series control section.
GEOGRAPHIC SETTING: The Buckhart soils formed in loess and are on summits on ground moraines. Slope ranges from 0 to 5 percent. Mean annual air temperature ranges from 50 to 54 degrees F., mean annual precipitation ranges from 34 to 40 inches, frost-free period ranges from 160 to 190 days, and elevation ranges from 400 to 800 feet above sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Elkhart, Ipava, Muscatune, Newvienna, Osco, Sable, and Virden soils. The well drained Elkhart soils have carbonates within depths of 40 inches, are on similar parts of the landscape, and are also on sideslopes along drainageways. The somewhat poorly drained Ipava and Muscatune soils and the poorly drained Sable and Virden soils are on nearly level broad interstream divides on positions at lower elevations, and they form a hydrosequence with the Buckhart soils. In addition, the Ipava and Virden soils have a fine-textured particle size control section. The moderately well drained Newvienna soils are on similar positions on the landscape and have a thinner dark surface layer. The well drained Osco soils are on sideslopes along drainageways.
DRAINAGE AND PERMEABILITY: Moderately well drained. The potential for surface runoff is low. Permeability is moderate. The depth to the top of an apparent seasonal high water table ranges from 2 to 3.5 feet at some time between February and April in most years.
USE AND VEGETATION: Most areas of the Buckhart soils are cultivated. Corn, soybeans, and wheat are the principal crops. Native vegetation is prairie grasses.
DISTRIBUTION AND EXTENT: In Central and
western Illinois. The soils are of moderate extent in MLRA 108B.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Christian County, Illinois, 1999. The Buckhart series was named for the township where the type location is located in Christian County.
REMARKS: Buckhart soils were formerly included with the Tama series (Typic Argiudolls). The representative data mapunit for this pedon is DMU ID 44521 for MO-11.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to a depth of 15 inches (Ap and A
horizons). Argillic horizon - the zone from approximately 15 to 52 inches (Bt1,
Bt2, and Bt3 horizons). Udic moisture regime.
Taken from Natural Resources Conservation Service: http://ortho.ftw.nrcs.usda.gov/osd/dat/B/BUCKHART.html.