LOCATION PLATO MOEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Aquic Fragiudalfs
TYPICAL PEDON: Plato silt loam - on a 3 percent slope in pasture at an elevation of 995 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; brown (10YR 4/3) silt loam, very pale brown (10YR 7/3) dry; weak fine granular structure; friable; common coarse roots; neutral; clear smooth boundary. (4 to 9 inches thick)
Bt1--6 to 12 inches; yellowish brown (10YR 5/6) silty clay loam; moderate fine subangular blocky structure; friable; common medium roots; few distinct clay films of faces of peds; very strongly acid; clear smooth boundary.
Bt2--12 to 17 inches; yellowish brown (10YR 5/6) silty clay loam; moderate fine and medium subangular blocky structure; firm; common fine roots; common distinct clay films on faces of peds; common fine prominent light brownish gray (10YR 6/2) iron depletions and distinct strong brown (7.5YR 4/6) masses of iron accumulation; few fine dark brown soft masses of iron and manganese accumulation; very strongly acid; clear smooth boundary.
Bt3--17 to 21 inches; light brownish gray (10YR 6/2) silty clay; moderate fine subangular blocky structure; firm; common fine roots; common distinct clay films on faces of peds; many fine prominent dark yellowish brown (10YR 4/6) masses of iron accumulation; very strongly acid; clear smooth boundary.
Bt4--21 to 29 inches; grayish brown (10YR 5/2) silty clay loam; moderate fine and medium subangular blocky structure; firm; few fine roots; common faint clay films on faces of peds; many medium prominent yellowish brown (10YR 5/6) masses of iron accumulation; very strongly acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 18 to 30 inches.)
2Btx--29 to 46 inches; grayish brown (10YR 5/2) extremely gravelly silt loam; moderate very coarse prismatic structure parting to moderate fine subangular blocky; very firm; about 65 percent brittleness; few faint clay films on faces of primary peds; common medium distinct dark yellowish brown (10YR 4/6) masses of iron accumulation; 70 percent subrounded chert gravel; strongly acid; gradual smooth boundary. (8 to 30 inches thick)
3Bt1--46 to 56 inches; dark red (10R 3/6) very gravelly clay; weak medium subangular blocky structure; very firm; few distinct clay films on faces of peds; common medium prominent reddish yellow (7.5YR 6/6) masses of iron accumulation and few fine prominent gray (10YR 5/1) iron depletions; 50 percent subrounded chert gravel; strongly acid; gradual smooth boundary.
3Bt2--56 to 62 inches; red (10R 4/6) gravelly clay; weak fine subangular blocky structure; very firm; few distinct clay films; common medium prominent light gray (10YR 7/2) iron depletions and few fine prominent reddish yellow (7.5YR 6/6) masses of iron accumulation; 20 percent subrounded chert gravel; strongly acid.
TYPE LOCATION: Pulaski County, Missouri, about 2 3/4 miles east of Dixon, Missouri; 2,030 feet south and 1,015 feet west of the northeast corner of sec. 29, T. 38 N., R. 10 W.; USGS Dixon, Missouri quadrangle, latitude 37 degrees 59 minutes 27 seconds N. and longitude 92 degrees 02 minutes 36 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness and depth to bedrock is more than 60 inches. Depth to the fragipan is 20 to 36 inches. Chert content is less than 5 percent in the A and upper B horizons, 0 to 15 percent in the Bt horizon, 0 to 70 percent in the fragipan (2Btx) and 10 to 50 percent in the 3Bt horizon.
The Ap or A horizon has value of 4 to 6, and chroma of 2 to 5. The E horizon, where present, has value of 4 to 6, and chroma of 2 to 6. The A and E horizons are silt loam, but eroded areas can be silty clay loam. Reaction is very strongly acid to neutral.
The upper part of the Bt horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 4 to 6. Iron depletions with value of 4 or more and chroma of 2 or less are present in the upper 10 inches of the argillic horizon. The lower Bt horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 1 to 4 with higher chroma iron masses or lower chroma iron depletions. It is silty clay loam, silty clay, or clay. Reaction is strongly acid to extremely acid, but may range up to neutral in areas that were limed.
The 2Btx horizon is mottled. Clay films, clay flows, or plugs are common. It is silt loam, loam, clay loam, or silty clay loam or their gravelly, very gravelly, or extremely gravelly analogues. Reaction is strongly acid to extremely acid.
The 3Bt horizon has mottled colors with hue of 10R to 10YR, value of 3 to 6, and chroma of 1 to 8. It is silty clay loam, clay loam, silty clay, or clay, or their gravelly, cobbly, very cobbly, or very gravelly analogues. Reaction is strongly acid to moderately alkaline.
COMPETING SERIES: This is the Rosati series. Rosati soils have a mollic colors in the surface layer.
GEOGRAPHIC SETTING: These nearly level and gently sloping soils are on upland broad ridgetops. Slope gradients are usually less than 4 percent, but range from 0 to 8 percent. The regolith consists of a thin mantle of loess over residuum from cherty limestone or dolomite. Mean annual temperature ranges from 54 to 57 degrees F., and mean annual precipitation ranges from 38 to 44 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Union, Viraton, and Wilderness soils. Union soils are moderately well drained and are on similar landscapes adjacent to the Plato soils. Viraton soils are fine-loamy and Wilderness soils are loamy-skeletal. These soils are on upper sideslopes and rounded ridgetops below the Plato soils.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Runoff is negligible to very high. Permeability is moderately slow above the fragipan, very slow in the fragipan, and moderate below the fragipan. The saturated hydraulic conductivity is moderately high above and below the fragipan and low in the fragipan. A seasonal high water table is perched from 1.0 to 2.0 feet during December through April in most years.
USE AND VEGETATION: Most of the acreage is used for hay and pasture. Post oak and blackjack oak dominate the remaining acreage. Native vegetation is hardwood forest.
DISTRIBUTION AND EXTENT: The Ozark region (MLRAs 116A and 116B) of southern Missouri. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Pulaski County, Missouri, 1984.
REMARKS: Diagnostic horizons and features recognized in this series are:
Ochric epipedon: the zone from the surface of the soil to a depth of 6 inches (Ap horizon).
Argillic horizon: the zone from approximately 6 inches to 62 inches (Bt1, Bt2, Bt3, 2Btx, 3Bt1 and 3Bt2 horizons).
Fragipan: the zone from approximately 29 to 46 inches (2Btx horizon).