LOCATION AUTOMBA MNEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Haplic Glossudalfs
TYPICAL PEDON: Automba silt loam with a convex slope of 1 percent on a till plain under a forest dominated by aspen. (Colors are for moist conditions unless otherwise noted.)
A1--0 to 2 inches; black (10YR 2/1) silt loam; moderate fine granular structure; very friable; many roots; about 1 percent coarse fragments; pH 5.1; clear wavy boundary. (1 to 4 inches thick)
B21hir--2 to 5 inches; dark brown (7.5YR 4/3) silt loam; moderate fine subangular blocky and some fine granular structure; very friable; many roots; about 1 percent coarse fragments; pH 5.1; clear smooth boundary. (2 to 8 inches thick)
B22hir--5 to 11 inches; brown (7.5YR 5/4) fine sandy loam with about 20 percent inclusions of yellowish brown (10YR 5/4); few fine faint strong brown mottles; moderate fine subangular blocky structure; very friable; many roots; about 2 percent coarse fragments; pH 5.0; clear wavy boundary. (4 to 8 inches thick)
B3--11 to 24 inches; reddish brown (5YR 4/3) fine sandy loam; few fine faint yellowish red (5YR 4/6) mottles; weak medium platy structure; very friable; few roots; about 10 percent coarse fragments; pH 5.4 in upper part; pH 5.8 in lower part; clear wavy boundary. (2 to 15 inches thick)
B&A--24 to 27 inches; dark reddish brown (5YR 3/3) fine sandy loam (B2t); reddish gray (5YR 5/2) fine sandy loam (A2) about 25 percent and occurring in the form of tongues that are about 20 mm across at the top; common fine distinct yellowish red (5YR 4/6) mottles in A2 and few fine faint dark reddish brown (2.5YR 3/4) mottles in B2t; weak coarse prismatic structure parting to weak medium and coarse subangular blocky; A2 firm and ruptures to a friable mass under medium pressure; few roots; common very fine tubular pores lined with moderately thick clay films in B2t; many fine and very fine tubular pores in A2; about 8 percent coarse fragments; pH 6.2; clear wavy boundary. (2 to 6 inches thick)
B21t--27 to 32 inches; dark reddish brown (5YR 3/3) fine sandy loam, reddish brown (5YR 4/4) coatings on faces of peds; few faint fine and medium yellowish red (5YR 4/6) mottles; weak coarse prismatic structure parting mostly to weak medium platy and moderate medium subangular blocky; firm; very few roots mostly on prism faces; common thin and moderately thick clay films on prisms and faces of peds; about 8 percent coarse fragments; pH 6.3; gradual smooth boundary. (4 to 8 inches thick)
B22t--32 to 40 inches; dark reddish brown (5YR 3/3) loam; moderate medium platy structure; firm; very few roots; very few tubular pores; few moderately thick clay films on upper faces of plate surfaces and a few thin clay films on lower plates; about 8 percent coarse fragments; pH 6.4; gradual smooth boundary. (4 to 10 inches thick)
B3t--40 to 46 inches; dark reddish brown (5YR 3/3) fine sandy loam; moderate medium platy structure; firm; very few roots; very few tubular pores; about 8 percent coarse fragments; few thin clay films on upper faces of plates; pH 6.7; gradual smooth boundary. (4 to 8 inches thick)
C--46 to 60 inches; dark reddish brown (5YR 3/3) fine sandy loam; moderate medium platy structure; firm; very few tubular pores; about 8 percent coarse fragments; pH 6.8.
TYPE LOCATION: Carlton County, Minnesota; 290 feet north and 907 feet west of the southeast corner of sec. 30, T. 47 N., R. 20 W.
RANGE IN CHARACTERISTICS: The thickness of solum ranges from 36 to 52 inches. Depth to free carbonates ranges from 55 to 100 inches. Thickness of the upper sequum ranges from 12 to 24 inches. The content of coarse fragments ranges from 0 to 12 percent in the upper sequum and from 4 to 15 percent in the lower sequum. Mean annual soil temperature ranges from 39 to 44 degrees F.
A thin O horizon is in some pedons. The A1 horizon has hue of 10YR, value of 2 or 3, and chroma of 1 or 2. Some pedons have a discontinuous A2 horizon with a maximum thickness of about 2 inches. The A horizon is fine sandy loam, very fine sandy loam, loam or silt loam. It is very strongly to medium acid.
The B horizon in the upper sequum has hue of 5YR or 7.5YR, value of 3 through 5, and chroma of 3 or 4. Mottles are lacking in this horizon in some pedons. The lower value or chroma or both are only in the upper part. It is fine sandy loam, very fine sandy loam, loam, or silt loam and ranges from very strongly to medium acid.
Some pedons have a thin A2 horizon immediately below the B horizon. In the A&B horizon the A2 material has hue of 5YR, value of 4 or 5, and chroma of 1 or 2 and is sandy loam or fine sandy loam. High chroma mottles commonly are present. The A2 horizon or material tongues into the upper part of the Bt horizon.
The Bt horizon has hue of 2.5YR or 5YR with value and chroma of 3 or 4. High chroma mottles commonly are in the upper part of this horizon. It is sandy loam, fine sandy loam, or loam and contains 12 to 18 percent clay. The Bt horizon ranges from medium to slightly acid in the upper part and slightly acid to neutral in the lower part.
The C horizon has hue of 2.5YR or 5YR, with value and chroma of 3 or 4. It is sandy loam, fine sandy loam, or loam. Bulk density in the C horizon ranges from 1.8 to 2.0 g/cc.
COMPETING SERIES: No other series is in this family. Closely related series are Ahmeek, Amery, Duluth, Milaca, and Ronneby. The Ahmeek and Milaca series lack an argillic horizon. The Amery series has a lower degree of base saturation in the argillic horizon. The Duluth series has a fine-loamy argillic horizon. The Ronneby and Milaca series have a single sequence of horizons.
GEOGRAPHIC SETTING: These soils have convex slopes with gradients of 1 to 18 percent on gently undulating to rolling glacial moraines and on drumlins. They formed in loamy glacial till of the Superior Lobe of the Late Wisconsin glaciation. A thin mantle of aeolian or water-deposited sediments overlies the till in some places. Mean annual temperature ranges from 37 to 43 degrees F., and mean annual precipitation ranges from 25 to 30 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: The main ones are the Parent, Twig, and Ronneby soils which formed in material similar to that of the Automba soils and which are members of a hydrosequence with the Automba soils. The Parent soils are poorly drained and have a moderately thick black A horizon and have nearly level slopes. The somewhat poorly drained Ronneby soils have nearly level slopes. The very poorly drained Twig soils have a mucky surface layer and have concave slopes. The well drained Ahmeek and Duluth soils are associated in some places. Also, organic soils are common associates.
DRAINAGE AND PERMEABILITY: Well and moderately well drained. Surface runoff is medium. Permeability is moderately slow.
USE AND VEGETATION: Most of these soils are forested. A few areas are cleared and are pastured or are cropped to small grains and forage crops. Native vegetation was mixed deciduous-coniferous forest.
DISTRIBUTION AND EXTENT: Northeastern Minnesota and possibly northern Wisconsin. Moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Carlton County, Minnesota, 1976.
REMARKS: This series would have been placed in the Brown Podzolic or Gray-Brown Podzolic great soil groups.
ADDITIONAL DATA: Refer to S68Minn-9-9 for results of some laboratory analysis of the typifying pedon and to MAES Central File Code Nos. 513 and 1088 for an additional pedon.