LOCATION ARLO SDEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, mesic Typic Calciaquolls
TYPICAL PEDON: Arlo clay loam, on a plane slope of less than 1 percent in a cultivated field. When described, the soil was moist throughout. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 11 inches; black (10YR 2/1) clay loam, dark gray (10YR 4/1) dry; weak fine and medium granular structure; slightly hard, friable, slightly sticky, and slightly plastic; strong effervescence (11 percent calcium carbonate); slightly alkaline; abrupt smooth boundary. (6 to 23 inches thick)
Ak--11 to 18 inches; very dark gray (10YR 3/1) loam, gray (10YR 5/1) dry; weak medium subangular blocky structure parting to weak fine and medium granular; slightly hard, friable; violent effervescence (20 percent calcium carbonate); moderately alkaline; gradual wavy boundary. (0 to 12 inches thick)
Bkg1--18 to 31 inches; gray (10YR 5/1) sandy clay loam, light gray (10YR 7/1) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, and slightly plastic; violent effervescence (24 percent calcium carbonate); moderately alkaline; gradual wavy boundary.
Bkg2--31 to 35 inches; dark grayish brown (2.5Y 4/2) sandy clay loam, light brownish gray (2.5Y 6/2) dry; common distinct fine gray (10YR 5/1) redox depletions and light olive brown (2.5Y 5/6) redox concentrations; massive; soft, very friable, slightly sticky, and slightly plastic; few fine dark concretions (Fe and Mn oxides); many coarse accumulations of carbonate; strong effervescence (12 percent calcium carbonate); moderately alkaline; clear smooth boundary. (Combined Bk horizons is 8 to 25 inches thick.)
2Cg1--35 to 50 inches; olive brown (2.5Y 4/4) gravelly sand, light olive brown (2.5Y 5/4) dry; common fine and medium prominent dark brown (7.5YR 3/2) redox depletions and yellowish brown (10YR 5/6) redox concentrations; single grain; loose; common fine dark concretions (Fe and Mn oxides); strong effervescence (7 percent calcium carbonate); moderately alkaline; gradual wavy boundary.
2Cg2--50 to 60 inches; light brownish gray (2.5Y 6/2) loamy sand, light gray (2.5Y 7/2) dry; common fine and medium prominent yellowish brown (10YR 5/6) redox concentrations; single grain; few pebbles; loose; common rounded shale chips; few fine dark concretions (Fe and Mn oxides); sand grains coated with calcium carbonate; strong effervescence (6 percent calcium carbonate); moderately alkaline.
TYPE LOCATION: Turner County, South Dakota; about 1 mile west and 1/2 mile south of Davis; 1,720 feet south and 75 feet east of the northwest corner of sec. 5, T. 97 N., R. 52 W.
RANGE IN CHARACTERISTICS: The depth to sand and gravel ranges from 20 to 40 inches. The mollic epipedon ranges from 7 to 30 inches thick. The soil typically is calcareous throughout, but some pedons in native grass lack free carbonates to a depth of 6 inches. The calcic horizon has a calcium carbonate equivalent of 15 to 40 percent.
The Ap or A horizon has hue of 10YR, 2.5Y, or neutral; value of 2 or 3 and 3 to 5 dry; and chroma of 0 to 1. Typically it is loam or clay loam but is silt loam or silty clay loam in some pedons. It ranges from neutral to moderately alkaline.
The Ak horizon has a hue of 10YR, 2.5Y, 5Y, or neutral; value of 2 or 3 and 3 to 5 dry; and chroma of 0 to 1. Some pedons have chroma of 2 and distinct or prominent mottles are present. Typically, it is loam or clay loam. It is slightly or moderately alkaline.
The Bk horizon has a hue of 10YR, 2.5Y, 5Y, or neutral; value of 3 to 6 and 5 to 8 dry; and chroma of 1 or 2. It typically has common to many distinct and prominent mottles. Typically, it is stratified loam, sandy clay loam, or clay loam, but is sandy loam or gravelly clay loam in the lower part of some pedons. Few or common nests of gypsum and other salts are in some pedons. It is slightly or moderately alkaline.
Some pedons have a C horizon with color and texture of the Bk horizon.
The 2C horizon has a hue of 10YR, 2.5Y, or 5Y; value of 3 to 6 and 5 to 7 dry; and chroma of 1 to 4. Typically, it is stratified gravelly sand, gravelly loamy sand, very gravelly sand, very gravelly loamy sand, sand, or loamy sand, but thin layers of contrasting material are present in some pedons. It contains up to 50 percent gravel. It is slightly or moderately alkaline.
COMPETING SERIES: These include the Harcot series in the same family. Harcot soils receive more rainfall.
GEOGRAPHIC SETTING: Arlo soils are level or nearly level on broad drainageways and flats on glacial outwash plains and flood plains. Slope gradients are less than 2 percent, and surfaces are plane or slightly concave. They formed in loamy alluvium overlying stratified sand and gravel. The mean annual temperature ranges from 45 to 52 degrees F, and mean annual precipitation ranges from 18 to 26 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Delmont, Dimo, Enet and Storla soils. Delmont, Dimo, and Enet soils do not have a calcic horizon and are on higher parts of the landscape. In addition, the Delmont soils have sand and gravel at depths of 10 to 20 inches. Storla soils are better drained and have higher chroma below the mollic epipedon and are on slightly higher parts of the landscape.
DRAINAGE AND PERMEABILITY: Poorly drained and very poorly drained. Runoff is low. Permeability is moderate in the upper part and very rapid in the underlying sand and gravel. Seasonal high water table typically is within 1 foot of the surface in most years.
USE AND VEGETATION: Areas are cultivated or in native grass. Alfalfa, corn, and tame pasture are the principal crops. The native vegetation is mainly big bluestem, indiangrass, switchgrass, prairie cordgrass, and sedges.
DISTRIBUTION AND EXTENT: East-central and southeastern South Dakota, east of the Missouri River. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Aurora County, South Dakota, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 18 inches (Ap, Ak horizon); calcic horizon - the zone from about 11 to 35 inches (Ak, Bkg1, Bkg2 horizon).