LOCATION TARA MNEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Aquic Hapludolls
TYPICAL PEDON: Tara silt loam with 1 percent slightly concave west-facing slope on a ground moraine in a cultivated field. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 7 inches; black (10YR 2/1) silt loam, very dark gray (10YR 3/1) dry; weak very fine subangular blocky structure; friable; neutral; abrupt smooth boundary.
A--7 to 15 inches; black (10YR 2/1) silt loam, very dark gray (10YR 3/1) dry; weak and moderate very fine subangular blocky structure; friable; neutral; clear smooth boundary.
(Combined thickness of A horizons is 16 to 24 inches)
AB--15 to 19 inches; very dark gray (10YR 3/1) silt loam, very dark gray (10YR 3/1) and dark gray (10YR 4/1) dry; moderate very fine and fine subangular blocky structure; friable; few masses of dark grayish brown (2.5Y 4/2); neutral; clear wavy boundary.
Bw--19 to 27 inches; dark grayish brown (2.5Y 4/2) silt loam; weak medium and coarse prismatic structure parting to weak fine and medium subangular blocky; friable; neutral; gradual wavy boundary. (4 to 20 inches thick)
Bk--27 to 33 inches; light olive brown (2.5Y 5/4) loam; weak fine subangular blocky structure; friable; about 2 percent rock fragments; few fine distinct grayish brown (2.5Y 5/2) Fe depletions and few fine prominent dark yellowish brown (10YR 4/4) Fe concentrations; few threads and masses of lime; strongly effervescent; moderately alkaline; gradual wavy boundary. (0 to 20 inches thick)
2C1--33 to 38 inches; light olive brown (2.5Y 5/4) loam; massive; friable; about 4 percent gravel; common medium distinct grayish brown (2.5Y 5/2) Fe depletions; strongly effervescent; slightly alkaline; gradual smooth boundary. (0 to 20 inches thick)
2C2--38 to 60 inches; grayish brown (2.5Y 5/2) loam; many coarse distinct light olive brown (2.5Y 5/4) mottles; massive; friable; about 5 percent rock fragments; few iron oxide and manganese oxide stains; strongly effervescent; slightly alkaline.
2C3--60 to 80 inches; light olive brown (2.5Y 5/4) loam, massive, friable; about 5 percent rock fragments; few iron oxide and manganese oxide stains, many coarse distinct light grayish brown (2.5Y 5/2) Fe depletions; strongly effervescent; slightly alkaline.
TYPE LOCATION: Swift County, Minnesota; about 9 miles north of Holloway; about 1,850 feet north and 80 feet west of the southeast corner of sec. 14, T. 122 N., R. 42 W., USGS Hancock SW, Minnesota quadrangle, lat. 45 degrees 22 minutes 28 seconds N., lon. 95 degrees 53 minutes 30 seconds W., NAD27.
RANGE IN CHARACTERISTICS: The depth to free carbonates range from 20 to 40 inches. The mollic epipedon is 16 to 30 inches thick. The silty mantle has 18 to 27 percent clay and is 25 to 40 inches thick. It typically does not have rock fragments. Horizons in glacial till have 1 to 10 percent rock fragments by volume. A thin stone line with as much as 30 percent rock fragments is between the two materials in some pedons.
The A horizon has hue of 10YR or 2.5Y, value of 2 or 3 and chroma of 1 or 2. It typically is silt loam or loam high in content of very fine sand, but silty clay loam is in the range. It is slightly acid or neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 3 through 5 and chroma of 2 through 4. It is typically silt loam or loam high in content of very fine sand, but ranges to silty clay loam in some subhorizons. It is neutral or slightly alkaline.
Some pedons have a thin 2Bw horizon.
The Bk horizon has hue of 2.5Y, value of 4 through 6 and chroma of 2 through 4. It is typically silt loam but ranges to loam high in the content of very fine sand. It is moderately alkaline or slightly alkaline. The calcium carbonate equivalent may or may not qualify for meeting the criteria for a calcic.
The 2C horizon has hue of 2.5Y, value of 4 or 5 and chroma of 2 through 4. It is loam or clay loam. It is slightly alkaline or moderately alkaline.
COMPETING SERIES: This is the Brookings series. Brookings soils have more than 27 percent clay in the series control section.
GEOGRAPHIC SETTING: These soils have concave to slightly convex slopes with gradient of 1 to 3 percent on glacial moraines and lake plains. They formed in a silty mantle of glacial lacustrine sediments or loess that is 25 to 40 inches thick overlying loamy calcareous glacial till. These sediments are Late Wisconsinan age. Mean annual precipitation ranges from 18 to 26 inches, and mean annual air temperature from 40 to 45 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Colvin, Doland, McIntosh, Perella, and Quam soils, which are members of a drainage sequence with Tara soils. Well drained Doland soils are formed in a thinner silty mantle and are on higher lying terrain. Moderately well and somewhat poorly drained McIntosh soils are on nearby low knolls. They have a silty mantle similar in thickness to the Tara soils. Poorly drained Colvin and Perella soils are on adjacent lower lying nearly level positions. Very poorly drained Quam soils are in depressions. Colvin, Perella, and Quam soils formed in a silty mantle more than 40 inches in thickness.
DRAINAGE AND PERMEABILITY: These soils are moderately well drained. Surface runoff is slow. Permeability is moderate.
The apparent seasonal high water table is at 2.5 to 3.5 feet at some time during the months of March to June in normal years.
USE AND VEGETATION: These soils are mostly in cropland. Principal crops are corn, soybeans, and small grains. Native vegetation was tall grass prairie.
DISTRIBUTION AND EXTENT: Western Minnesota; moderately extensive.
MLRA OFFICE RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Stevens County, Minnesota, 1978.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 19 inches (Ap, A, and AB horizons); cambic horizon- from a depth of 19 to 27 inches (Bw horizon), calcic horizon-from a depth of 27 to 33 inches (Bk horizon), aquic moisture regime.