LOCATION TONKA ND+MN SDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Argiaquic Argialbolls
TYPICAL PEDON: Tonka silt loam - formerly cultivated. (Colors for moist soil unless otherwise stated)
A--0 to 13 inches; black (10YR 2/1) silt loam, dark gray (10YR 4/1) dry; moderate fine granular structure parting to moderate thin platy; soft, friable, slightly sticky and slightly plastic; many fine roots; many fine pores; slightly acid; abrupt wavy boundary. (6 to 24 inches thick)
E--13 to 19 inches; dark gray (10YR 4/1) loam, light gray (10YR 7/1) dry; many medium prominent dark brown (10YR 3/3) and dark yellowish brown (10YR 3/4) redoximorphic concentrations; moderate thin platy and moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; moderately acid; abrupt irregular boundary. (4 to 18 inches thick)
Bt1--19 to 24 inches; very dark gray (10YR 3/1) silty clay loam, grayish brown (10YR 5/2) dry; common fine faint brown (10YR 4/3) redoximorphic concentrations; strong coarse prismatic structure parting to moderate very fine angular blocky; very hard, firm, sticky and slightly plastic; common fine roots; bleached sand grains coat tops of prisms and vertical faces of peds; moderately acid; gradual wavy boundary.
Bt2--24 to 34 inches; dark grayish brown (10YR 4/2) silty clay loam, light brownish gray (10YR 6/2) dry; moderate coarse prismatic structure parting to moderate very fine angular blocky; very hard, firm, sticky and slightly plastic; common fine roots; bleached sand grains coat faces of peds; moderately acid; gradual wavy boundary. (Combined Bt horizons 8 to 35 inches thick)
2BC--34 to 50 inches; dark grayish brown (2.5Y 4/2) clay loam, light brownish gray (2.5Y 6/2) dry; common medium distinct dark yellowish brown (10YR 3/4) redoximorphic concentrations; weak coarse prismatic structure parting to moderate fine subangular blocky; very hard, firm, sticky and slightly plastic; few fine roots; common fine very dark brown (10YR 2/2) manganese concretions; about 2 percent gravel; neutral; gradual wavy boundary. (0 to 20 inches thick)
2Cg--50 to 60 inches; gray (5Y 5/1) clay loam, light gray (5Y 6/1) dry; many medium distinct dark brown (7.5YR 4/4) redoximorphic concentrations; weak fine platy and moderate very fine angular blocky structure; hard, friable, sticky and slightly plastic; few fine roots; common fine very dark brown (10YR 2/2) manganese concretions; about 3 percent gravel; strong effervescence; slightly alkaline.
TYPE LOCATION: Ransom County, North Dakota; about 5 miles west of Enderlin; 2,500 feet west and 590 feet south of the northeast corner, sec. 2, T. 136 N., R. 56 W.
RANGE IN CHARACTERISTICS: Depth to carbonates commonly is 28 to 40 inches but ranges from 20 to more than 60 inches. The depth to the Bt horizon ranges from 12 to 28 inches. The soil commonly is free of rock fragments, but in some pedons the lower part of the solum and the substratum contain pebbles. Some pedons have surface stones.
The A horizon has hue of 10YR or is neutral, value of 2 or 3 and 3 to 5 dry, and chroma of 1 or less. It is silt loam, loam, clay loam or silty clay loam. It is moderately acid to slightly alkaline.
The E horizon has hue of 10YR or 2.5Y or is neutral, value of 3 to 5 and 5 to 7 dry, and chroma of 2 or less. It is loam, silt loam, very fine sandy loam or silty clay loam. The E horizon extends into the Bt horizon in many profiles and bleached sand and silt grains coat faces of peds in the Bt horizon. It is moderately acid to neutral.
The Bt horizon has hue of 10YR, 2.5Y or 5Y, value of 2 to 4, and chroma of 1 or 2. It has is a wide range in amount and distinctness of redoximorphic features. The Bt horizon is clay loam, silty clay loam, silty clay or clay averaging between 35 and 45 percent clay. It is moderately acid to slightly alkaline. Some pedons have Bk, Bg, BC, 2Bk or 2BC horizons below the Bt horizon that may or may not be gleyed.
The Cg horizon has hue of 10YR, 2.5Y or 5Y, value of 2 to 6 and 3 to 7 dry, and chroma of 1 to 6. It typically is silty clay loam, clay loam or loam, but textures of silty clay, clay, silt loam or sandy clay loam are allowed. It is neutral to moderately alkaline. The C horizon is not gleyed in some pedons. Textures ranging from loamy fine sand to clay are allowed below a depth of 40 inches.
COMPETING SERIES: This is the Enloe series. Enloe soils contain more 45 percent clay in the Bt horizon.
GEOGRAPHIC SETTING: Tonka soils are in plane or slightly concave, closed basins and depressions on till and glacial lake plains. Slope ranges from 0 to 1 percent. The soils formed in local alluvium over till or glaciolacustrine deposits. The mean annual air temperature is about 37 to 48 degrees F, and the mean annual precipitation ranges from about 12 to 24 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barnes, Forman, Hamerly, Max, Parnell, Svea and Williams soils. Barnes, Forman, Hamerly, Max, Svea and Williams soils are on higher lying positions. These soils are well to somewhat poorly drained, and do not have albic horizons or low chroma redoximorphic features in the argillic horizon. In addition, Hamerly soils have a calcic horizon at depths of less than 16 inches. Parnell soils are in deeper and commonly larger depressions. They do not have albic horizons and are very poorly drained.
DRAINAGE AND PERMEABILITY: Poorly drained. Slowly permeable. Runoff is ponded. A seasonal high water table is at a depth of 0.5 foot above the surface to 1 foot below the surface at some time during the period April through June.
USE AND VEGETATION: Used for small grains, hay and pasture. Native vegetation is tall grasses, sedges and rushes.
DISTRIBUTION AND EXTENT: Widely distributed on the glaciated plains of North Dakota, northeastern South Dakota, and western Minnesota. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Richland County, North Dakota, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 13 inches (A horizon); albic horizon - the zone from 13 to 19 inches (E horizon); argillic horizon - the zone from 19 to 34 inches (Bt1 and Bt2 horizons); Alboll criteria - chroma of 1 and redoximorphic concentrations in the albic horizon.