LOCATION BONA MOEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, semiactive, mesic Typic Paleudolls
TYPICAL PEDON: Bona gravelly silt loam on a north-facing, convex, 5 percent slope in pasture at an elevation of 1,080 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; very dark gray (10YR 3/1) gravelly silt loam, dark grayish brown (10YR 4/2) dry; weak medium granular structure; friable; many fine roots; 25 percent subrounded chert gravel; moderately acid; clear smooth boundary.
A--6 to 18 inches; very dark grayish brown (10YR 3/2) very gravelly silt loam, brown (10YR 5/3) dry; moderate medium granular structure; friable; many fine roots; 55 percent subrounded chert gravel; slightly acid; gradual wavy boundary. (Combined thickness of the Ap and A horizons ranges from 10 to 20 inches.)
Bt1--18 to 24 inches; dark brown (7.5YR 3/4) extremely gravelly silt loam; weak fine subangular blocky structure; friable; common fine roots; common distinct clay films on faces of peds; 65 percent subrounded chert gravel; 3 percent subrounded chert cobbles; slightly acid; gradual wavy boundary. (4 to 10 inches thick)
2Bt2--24 to 30 inches; yellowish red (5YR 4/6) very gravelly clay; moderate fine subangular blocky structure; firm; common fine roots; many distinct clay films on faces of peds; 45 percent subrounded chert gravel; moderately acid; gradual wavy boundary. (5 to 12 inches thick)
3Bt3--30 to 40 inches; red (2.5YR 4/6) clay; moderate fine angular blocky structure; firm; few fine roots; common distinct clay films on faces of peds; 10 percent subrounded chert gravel; very strongly acid; gradual wavy boundary.
3Bt4--40 to 62 inches; red (2.5YR 4/6) clay; common fine distinct yellowish red (5YR 5/8) mottles; moderate fine angular blocky structure; firm; few fine roots; common distinct clay films on faces of peds; 10 percent subrounded chert gravel; very strongly acid; gradual wavy boundary.
3Bt5--62 to 72 inches; yellowish red (5YR 4/6) clay; many medium distinct red (2.5YR 4/6) diagonal streaks; moderate fine angular blocky structure; firm few fine roots; common distinct clay films on faces of peds; 5 percent subrounded chert gravel and 2 percent subrounded chert cobbles; moderately acid.
3R--72 inches; dolostone.
TYPE LOCATION: Polk County, Missouri; about two miles southwest of Bolivar; 1,425 feet west and 800 feet south of the northeast corner of sec. 21, T. 33 N., R. 23 W.; Bolivar USGS quadrangle; latitude 37 degrees 32 minutes 24 seconds N. and longitude 93 degrees 27 minutes 17 seconds W..
RANGE IN CHARACTERISTICS: Depth to a lithic contact with dolomite or limestone ranges from 60 to 80 inches. Clay content of the particle size control section averages 35 to 55 percent and rock fragment content averages 35 to 60 percent.
Ap and A horizon:
Value: 2 or 3 moist, 3, 4 or 5 dry
Chroma: 1 to 3
Fine-earth: silt loam or loam
Rock fragments: 10 to 65 percent gravel and 0 to 35 percent cobbles
Reaction: strongly acid to neutral
BA or AB horizon (where present):
Hue: 5YR to 10YR
Value: 3 or 4
Chroma: 3 to 6
Fine-earth: silt loam or silty clay loam
Rock fragments: 20 to 60 percent gravel and 0 to 25 percent cobbles
Reaction: strongly acid to neutral
Bt horizon:
Hue: 2.5YR to 10YR
Value: 3 or 4
Chroma: 3 to 6
Fine-earth: silt loam, loam, clay loam, or silty clay loam
Rock fragments: 10 to 65 percent gravel and 0 to 35 percent cobbles
Reaction: strongly acid to neutral
2Bt horizon:
Hue: 2.5YR to 7.5YR
Value: 4 or 5
Chroma: 4 to 8
Fine-earth: silty clay or clay
Rock fragments: 35 to 50 percent gravel and 0 to 10 percent cobbles
Reaction: very strongly acid to neutral
3Bt horizon
Hue: 2.5YR to 10YR
Value: 4 to 6
Chroma: 6 to 8
Fine-earth: silty clay or clay
Rock fragments: 0 to 15 percent gravel and 0 to 10 percent cobbles
Reaction: very strongly acid to slightly alkaline
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Bona soils are on ridgetops and side slopes in upland prairie areas of the western border Ozarks region. Slope ranges from 3 to 15 percent. These soils formed in gravelly colluvium and the underlying residuum from cherty dolomite or limestone. Mean annual temperature ranges from 54 to 58 degrees F, and mean annual precipitation ranges from 40 to 46 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cedargap, Creldon, Goss, Hoberg, and Goodson soils. The Cedargap soils are loamy-skeletal and are below the Bona soils immediately adjacent to narrow drainageways. The Creldon and Hoberg soils have fragipans and are on broad upland ridges above the Bona soils. Goss soils have an ochric epipedon and are on similar landforms. Goodson soils have clayey particle size control sections and are on higher convex ridges.
DRAINAGE AND PERMEABILITY: Well drained, permeability is moderately slow and surface runoff is medium.
USE AND VEGETATION: Used mainly for pasture or hayland. Native vegetation is tall prairie grass.
DISTRIBUTION AND EXTENT: Ozark Border area (MLRA 116B) of southwest Missouri. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Polk County, Missouri, 1995.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - the zone from the surface of the soil to a depth of 18 inches (Ap and A horizons).
Argillic horizon - the zone from a depth of 18 to 72 inches.(Bt, 2Bt and 3Bt horizons).
ADDITIONAL DATA: University of Missouri Soil Characterization Laboratory: Pedon no. M9116730.