LOCATION HUMANSVILLE MOEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Endoaquolls
TYPICAL PEDON: Humansville silt loam, on a floodplain in a cropped field at an elevation of 895 feet. (Colors are for moist soil unless otherwise noted)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) silt loam, dark gray (10YR 4/1) dry; weak fine granular structure; friable; common very fine roots; moderately acid (pH 5.8); clear smooth boundary. (0 to 10 inches thick)
A--7 to 24 inches; very dark gray (10YR 3/1) silty clay loam, dark gray (10YR 4/1) dry; weak very fine granular structure; firm; common brown (10YR 4/3) masses of iron accumulation; slightly acid (pH 6.4); gradual smooth boundary. (14 to 36 inches thick)
Bg1--24 to 44 inches; dark grayish brown (10YR 4/2) silty clay loam; weak fine subangular blocky structure; firm many distinct very dark gray (10YR 3/1) organic coats of faces of peds; few fine dark yellowish brown (10YR 4/4) masses of iron accumulation; neutral (pH 6.6); gradual smooth boundary.
Bg2--44 to 60 inches; grayish brown (10YR 5/2) silty clay loam; moderate fine subangular blocky structure; firm; common distinct very dark gray (10YR 3/1) organic coats on faces of peds; commom dark yellowish brown (10YR 4/4) and common dark yellowish brown (10YR 4/6) masses of iron accumulation; neutral (pH 6.6). (Combined thickness of the Bg horizon is 24 to 56 inches)
TYPE LOCATION: Polk County, Missouri; about 2 miles south and 1 mile east of the town of Sentinel; 2,000 feet north and 2,400 feet west of the southeast corner of section 20, T. 35 N., R. 21 W.; USGS Sentinel quadrangle; Latitude 37 degrees 34 minutes 58 seconds N., Longitude 93 degrees 28 minutes 8 seconds W.
RANGE IN CHARACTERISTICS:
Mollic epipedon: 24 to 36 inches thick
Solum thickness: 38 to more than 80 inches
Mean annual soil temperature at 20 inches: 55 to 59 degrees F.
Ap, A, or BA horizon
Hue: 10YR
Value: 2 or 3
Chroma: 1 to 3
Texture: silt loam or silty clay loam
Rock fragments: 0 to 5 percent gravel
Reaction: neutral to strongly acid
Bg horizon
Hue: 10YR, 2.5YR, or 5Y
Value: 4 to 6
Chroma: 1 or 2
Texture: silty clay loam, clay loam, silty clay, or clay
Rock fragments: 0 to 5 percent gravel
Reaction: neutral to strongly acid
Cg horizon (where present)
Hue: 10YR, 2.5Y, or 5Y
Value: 4 to 6
Chroma: 1 or 2
Texture: clay, silty clay or silty clay loam
Rock fragments: 0 to 5 percent gravel
Reaction: neutral or slightly acid
COMPETING SERIES: These are the Catherine, Colo, Otter, Sawmill, and Whitewood series. Cathrine and Otter soils have a mean annual soil temperature of 47 to 52 degrees F.. Colo soils have a mean annual soil temperature from 49 to 55 degrees F., and have a mollic epipedon thicker than 36 inches. Sawmill soils have a mean annual soil temperature of about 52 degrees F.
GEOGRAPHIC SETTING: Humansville soils are on nearly level to depressional areas in flood plains and drainageways. Slopes range from 0 to 3 percent. These soils formed in silty and clayey alluvium. Mean annual temperature ranges from 54 to 58 degrees F. and the mean annual precipitation ranges from 38 to 45 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cedargap, Hepler, Horsecreek, Moniteau, Sturkie, and Verdigris series. Cedargap soils have more than 35 percent rock fragments in the series control section. Hepler, Horsecreek, and Moniteau soils do not have a mollic epipedon. Sturkie soils are well drained. Verdigris soils are well drained. All of these soils are on higher elevations in the floodplain.
DRAINAGE AND PERMEABILITY: Poorly drained. Runoff is negligible. Permeability is moderately slow. Flooding is occasional to frequent. A seasonally high water table is present at 0.5 to 1 foot during late winter and early spring in most years.
USE AND VEGETATION: Nearly all areas have been cleared and are used for growing cultivated crops, hay, and pasture. Crops include corn, soybeans, small grains, grasses and legumes. Native vegetation was mostly oaks, maples, elms, sycamore, poplars, black gum, shagbark hickory, and ash with grass and forbes as the understory.
DISTRIBUTION AND EXTENT: The Ozarks region (MLRA's 116B and 116A) of southern Missouri and possibly northern Arkansas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Polk County, Missouri, 1998.
REMARKS: Diagnostic horizons and features are as follows:
Mollic epipidon - the zone from the surface of the soil to a depth of 24 inches (Ap and A horizon)
Cumulic feature - a mollic epipedon that is 24 to 36 inches thick
Cambic horizon - the zone from 24 to 60 inches (Bg horizon)
Aquic feature - high chroma iron accumulations within 12 inches of the surface and in the lower part of the mollic epipedon.
These soils were formerly included in the Lanton series in mapping. Lanton soils are thermic.
ADDITIONAL DATA: University of Missouri soil characterization laboratory number M9116718. Pedon site ID number is 91MO167132.