LOCATION SPEED MOEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Argiaquic Argialbolls
TYPICAL PEDON: Speed silt loam - on a linear flood plain of 1 percent slope in soybeans at an elevation of 765 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam; dark grayish brown (10YR 4/2) dry; weak fine granular structure; friable; many very fine roots; neutral; abrupt smooth boundary.
A--8 to 14 inches; very dark gray (10YR 3/1) silt loam; dark gray (10YR 4/1) dry; moderate fine granular structure; friable; many very fine roots; few distinct iron and manganese oxide stains; moderately acid; clear smooth boundary. (Combined thickness of the Ap and A horizons is 10 to 24 inches.)
Eg1--14 to 20 inches; dark grayish brown (10YR 4/2) silt loam; weak medium platy structure parting to weak very fine subangular blocky; friable; common very fine roots; few fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; few distinct iron and manganese oxide accumulations; common distinct clay depletions on faces of peds; common distinct organic coatings; strongly acid; clear smooth boundary.
Eg2--20 to 27 inches; grayish brown (10YR 5/2) silt loam; weak medium platy structure parting to weak very fine subangular blocky; friable; few very fine roots; common fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; few distinct iron and manganese oxide stains; many prominent clay depletions on faces of peds; strongly acid; clear smooth boundary. (Combined thickness of the E horizon is 10 to 24 inches.)
Btg1--27 to 31 inches; dark grayish brown (10YR 4/2) silt loam; weak fine subangular blocky structure; friable; few very fine roots; few distinct clay films on faces of peds; common fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; few fine iron and manganese oxide accumulations; many distinct silt coats on faces of peds; few distinct organic stains; very strongly acid; gradual smooth boundary.
Btg2--31 to 35 inches; dark grayish brown (10YR 4/2) silt loam; moderate fine subangular blocky structure; firm; few very fine roots; common distinct clay films on faces of peds; common fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; few fine iron and manganese oxide accumulations; common distinct silt coats on faces of peds; very strongly acid; gradual smooth boundary.
Btg3--35 to 48 inches; dark grayish brown (10YR 4/2) silty clay loam; moderate very fine subangular blocky structure; firm; few very fine roots; many distinct clay films on faces of peds; many fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; few fine iron and manganese oxide accumulations; few distinct silt coats on faces of peds; strongly acid; gradual smooth boundary.
Btg4--48 to 60 inches; dark grayish brown (10YR 4/2) and grayish brown (10YR 5/2) silt loam; weak fine subangular blocky structure; firm; few very fine roots; many fine distinct dark yellowish brown (10YR 4/4) masses of iron accumulation throughout; few fine iron and manganese oxide accumulations; common distinct clay films on faces of peds; few distinct silt coats in root channels; moderately acid.
TYPE LOCATION: Cooper County, Missouri; about 4 miles west and 3 miles south of Bunceton; 2850 feet south and 120 feet east of the northwest corner of sec. 14, T. 46 N., R. 18 W; Pilot Grove quadrangle, lat. 38 degrees 45 minutes 3 seconds N. and long. 92 degrees 52 minutes 33 seconds W..
RANGE IN CHARACTERISTICS: Thickness of the mollic epipedon is 10 to 24 inches. Depth to the top of the argillic is 24 inches or more. Clay percentage commonly averages from 18 to 27 percent in the particle size control section, but ranges to 30 percent. Sand content averages 5 to 10 percent in the series control section. The mean annual soil temperature is 55 to 59 degrees F..
The A horizon has color value of 2 or 3 and chroma of 1 to 3. Reaction is moderately acid to neutral.
The E horizon has hue of 10YR or 2.5Y, value of 3 to 6 and chroma of 1 or 2. Reaction is strongly acid to neutral.
The Bt or Btg horizon has hue of 10YR to 5Y, value of 3 to 6 and chroma of 1 to 4. It is silt loam or silty clay loam. Reaction is very strongly acid to neutral.
The BCg and Cg horizons, when present, have color similar to the Btg horizon. It is silt loam or silty clay loam. Reaction is strongly acid to neutral.
COMPETING SERIES: These are the Corley, Ebbert, Edgington, Knight, Marissa, Normal, Thorp, and Vesser series. Corley, Edgington, Knight, Marissa, Normal, Tharp, and Vesser soils average less than 54 degrees F. in the soil temperature control section. In addition, Corley and Normal soils have less than 5 percent sand in the particle size control section, Edgington soils formed entirely in loess, Knight soils have a mollic epipedon thicker than 24 inches, and Marissa soils have carbonates at 40 to 60 inches. Ebbert soils are less than 24 inches to the top of the argillic horizon and the solum formed in loess.
GEOGRAPHIC SETTING: Speed soils are on high floodplains, alluvial fans, and toeslopes and formed in alluvium. Slopes range from 0 to 5 percent. The mean annual temperature ranges from 53 to 58 degrees F., and mean annual precipitation ranges from 35 to 42 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dockery and Moniteau soils. Dockery soils do not have an argillic horizon and are on lower flood plains. Moniteau soils have an ochric epipedon and are on similar positions.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Runoff is low. Permeability is moderate. In undisturbed areas, the upper depth of an apparent water table is at 1.0 to 2.5 feet during November to May in most years. Flooding frequency is occasional or rare.
USE AND VEGETATION: Speed soils are used to grow cultivated crops, hay, and pasture. Native vegetation is tall prairie grasses.
DISTRIBUTION AND EXTENT: West-central Missouri. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Cooper County, Missouri, 1994.
REMARKS: Diagnostic horizons and features recognized in this series are: mollic epipedon - the zone from the surface of the soil to a depth of 14 inches (Ap and A horizons);
albic horizon - the zone from 14 to 27 inches (Eg1 and Eg2 horizon); argillic horizon - the zone from 27 to 60 inches (Btg1, Btg2, Btg3, Btg4 horizons).