LOCATION WILLOWFORK MOEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Argialbolls
TYPICAL PEDON; Willowfork silt loam - on a slope of about 1 percent in a cultivated field at an elevation of 990 feet. (Colors are for moist soil unless otherwise noted.
Ap--0 to 12 inches; very dark grayish brown (10YR 3/2) silt loam; grayish brown (10YR 5/2) dry; weak fine granular structure; friable; common fine and very fine roots throughout; common fine and very fine pores with moderate continuity; neutral; clear smooth boundary. (Combined thickness of the Ap and A horizons is 10 to 20 inches.)
Eg--12 to 26 inches; light brownish gray (10YR 6/2) silt loam; weak coarse platy structure parting to weak fine granular; friable; few fine and very fine roots throughout; common fine and very fine pores with moderate continuity; common medium faint brown (10YR 5/3) irregular masses of iron accumulation throughout; moderately acid; clear smooth boundary. (8 to 18 inches thick).
Btg1--26 to 34 inches; grayish brown (10YR 5/2) silty clay loam; moderate fine and medium subangular blocky structure; firm; few fine and very fine roots throughout; few very fine pores with low continuity; few faint continuous clay films on faces of peds; many medium distinct dark yellowish brown (10YR 4/4) irregular masses of iron accumulation throughout; common distinct silt coats on faces of peds; moderately acid; gradual smooth boundary.
Btg2--34 to 54 inches; dark gray (10YR 4/1) silty clay; moderate fine and medium subangular blocky structure; firm; few very fine roots throughout; few very fine pores with low continuity; few faint continuous clay films on faces of peds; common medium distinct dark yellowish brown (10YR 4/4) irregular masses of iron accumulations throughout; few distinct manganese stains on faces of peds; moderately acid; gradual smooth boundary. (Combined thickness of the Btg horizon is 20 to 36 inches.)
2Btg3--54 to 64 inches; gray (10YR 5/1) silty clay loam; weak fine subangular blocky structure; firm; few very fine pores with low continuity; few faint discontinuous clay films on faces of peds; common medium distinct dark yellowish brown (10YR 3/4) irregular masses of iron accumulation throughout; few distinct manganese stains on faces of peds; 10 percent chert gravel; neutral; gradual smooth boundary.
2Btg4--64 to 82 inches; grayish brown (10YR 5/2) silty clay loam; weak fine subangular blocky structure; firm; few very fine pores with low continuity; few faint discontinuous clay films on faces of peds; common medium distinct dark yellowish brown (10YR 3/4) irregular masses of iron accumulation throughout; 10 percent chert gravel; neutral.
TYPE LOCATION: Morgan County, Missouri; about 1 mile north and 2 miles east of Versailles; Versailles quadrangle, 850 feet north and 1200 feet west of the southeast corner of sec. 29, T. 43 N., R. 17 W.; lat. 38 degrees 27 minutes 07 seconds N. and long. 92 degrees 48 minutes 48 seconds W.
RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon ranges from 10 to 20 inches. The depth to the coarse fragments is 40 to 60 inches. The depth to the top of the argillic horizon ranges from 24 to 36 inches. The particle size control section averages between 35 and 48 percent clay.
The A or Ap horizon has value of 2 or 3 (4 or 5 dry), and chroma of 1 or 2. Reaction ranges from neutral to strongly acid.
The E horizon has value of 4 to 6, and chroma of 1 or 2. Reaction ranges from slightly acid to very strongly acid.
The Btg horizon has hue of 10YR or 2.5Y, value of 4 or 5 and chroma of 1 or 2. Iron accumulations commonly have higher chroma. It is silty clay loam or silty clay. Reaction is moderately acid or slightly acid.
The 2Btg horizon has colors similar to the Btg horizon. It is silt loam, loam, or silty clay loam or their gravelly analogues. Reaction is moderately acid or slightly acid.
COMPETING SERIES: These are the Chauncey, Plankinton, Rolfe and Sperry series. These soils do not have coarse fragments at depths of 40 to 60 inches.
GEOGRAPHIC SETTING: Willowfork soils are on nearly level, slightly concave footslopes and toeslopes along drainageways. They formed in 40 to 60 inches of loess over alluvium or colluvium that has 10 to 30 percent gravel. Slopes range from 0 to 3 percent. Mean annual temperature ranges from 55 to 57 degrees F., and the mean annual precipitation ranges from 36 to 42 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Crestmeade, Glensted, Friendly, Maplewood, and Speed soils. The Crestmeade, Friendly, Glensted, and Maplewood soils have dark colored surface layers less than 10 inches thick and are on higher ridges and side slopes. Speed soils average less than 35 percent clay in the particle size control section and are on flood plains.
DRAINAGE AND PERMEABILITY: Poorly drained. Surface runoff is low. Permeability is slow. In undisturbed areas, a perched water table has an upper limit of 0.0 to 1.5 feet during December to April in most years.
USE AND VEGETATION: Most areas are used to grow corn, soybeans, and small grain. Native vegetation is wet prarie grasses.
DISTRIBUTION AND EXTENT: Central Missouri (MLRA 116). The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Morgan County Missouri, 1996.
REMARKS: These soils have previously been mapped with the Chauncey series. Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface to a depth of 12 inches (A horizon); albic horizon - the zone from 12 to 26 inches (E horizon); argillic horizon - the zone from 26 to 82 inches or more (Btg horizons); abrupt textural change between the E and Btg horizons.