LOCATION TWIG MNEstablished Series
TAXONOMIC CLASS: Coarse-loamy, isotic, nonacid, frigid Histic Humaquepts
TYPICAL PEDON: Twig muck with a concave slope of less than 1 percent in a broad, drainageway on a ground moraine; pasture of reed canary grass. (Colors are for moist soil unless otherwise stated.)
Oa1--0 to 8 cm; black (10YR 2/1, broken face and rubbed) muck (sapric material); trace of fiber; moderate fine and very fine granular structure; slightly sticky, many roots; about 20 percent mineral material; extremely acid; gradual wavy boundary.
Oa2--8 to 20 cm; dark reddish brown (5YR 2/2, broken face and rubbed) muck (sapric material); about 40 percent fiber, about 10 percent rubbed; massive; nonsticky; many roots; about 10 percent mineral material; herbaceous fiber; extremely acid; gradual smooth boundary. (Combined thickness of the Oa horizons is 20 to 25 cm)
Oe--20 to 30 cm; reddish brown (5YR 4/4, broken face) mucky peat (hemic material), dark reddish brown (5YR 3/4, rubbed); about 80 percent fiber, about 35 percent rubbed; massive; nonsticky; many roots; about 30 percent mineral material; herbaceous fiber; extremely acid; clear smooth boundary. (0 to 15 cm thick)
A1--30 to 46 cm; black (10YR 2/1) mucky silt loam; weak medium subangular blocky structure; very friable; many charcoal fragments; about 10 percent woody fragments 5 to 10 cm in diameter and 20 to 70 cm long; extremely acid; clear smooth boundary.
A2--46 to 51 cm; black (10YR 2/1) silt loam; weak medium subangular blocky structure; friable; few very fine and fine vertical pores; thin pebble band in upper part; very strongly acid; abrupt wavy boundary. (Combined thickness of the A horizons is 2 to 20 cm)
Eg--51 to 66 cm; dark gray (10YR 4/1) loam; weak thin platy structure; friable; few very fine and fine vertical pores; 5 percent gravel; many medium prominent olive brown (2.5Y 4/4) and yellowish red (5YR 5/6) Fe concentrations; extremely acid; clear wavy boundary. (5 to 20 cm thick)
2Btg--66 to 91 cm; gray (10YR 5/1) fine sandy loam; moderate fine platy structure; friable; few thin clay films on upper faces of peds; common moderately thick gray (5YR 5/1) clay films in vertical root channels; few root channels surrounded by dark reddish brown (2.5YR 3/4); 5 percent gravel; many fine prominent dark reddish gray (5YR 4/2) Fe depletions and common fine prominent yellowish red (5YR 5/6) Fe concentrations; extremely acid; gradual wavy boundary. (0 to 51 cm thick)
2Bt--91 to 122 cm; reddish brown (5YR 4/3) fine sandy loam; moderate fine platy structure; friable; very few root channels; few moderately thick gray (5YR 5/1) clay films in root channels; 10 percent gravel; few fine distinct yellowish red (5YR 5/6) Fe concentrations; extremely acid; gradual smooth boundary. (0 to 28 cm thick)
2BCd--122 to 183 cm; reddish brown (5YR 4/3) fine sandy loam; moderate very coarse and extremely coarse prismatic structure parting to moderate fine and medium platy, few 2 to 3 millimeter oblique fractures 15 cm to 1 meter apart; very firm; 10 percent gravel; moderately acid.
TYPE LOCATION: Carlton County, Minnesota; 1,190 feet north and 40 feet east of the southwest corner of sec. 19, T. 47 N., R. 20 W.; USGS Quadrangle Heikkila Creek, Minn.; latitude 46 degrees 32 minutes 18 seconds N.; longitude 92 degrees 55 minutes 40 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: The upper organic soil layer has a thickness of 20 to 38 cm. Depth to dense till (densic contact) is 102 to 203 cm. The mineral soil has 0 to 12 percent rock fragments in the upper part and from 1 to 15 percent rock fragments in the till.
The O horizon has hue of 5YR to 10YR, value of 2 to 4 and chroma of 1 to 4. It is typically sapric or hemic material. It is extremely acid or very strongly acid.
The A horizon has hue of 10YR, 7.5YR, or 2.5Y or is neutral, value of 2 or 3, and chroma of 0 or 1. It is fine sandy loam, loam, sandy loam or silt loam or their mucky analogues. It is extremely acid to strongly acid.
The Eg horizon has hue of 5YR to 10YR, value of 4 to 6, and chroma of 1 or 2. It is fine sandy loam, loam, sandy loam or silt loam. It is extremely acid to strongly acid.
Some pedons have a Btg horizon that has hue of 2.5YR to 7.5YR, value of 3 to 5, and chroma of 2 to 6. Texture of the B horizon is loam or silt loam. Clay films may or may not be present in pedons. It is extremely acid to strongly acid.
The 2Btg horizon has hue of 5YR to 10YR or is neutral, value of 4 to 6 and chroma of 0 to 2. It is extremely acid to strongly acid.
Some pedons have Bg or Bw horizons.
The 2BCd horizon has hue of 2.5YR or 5YR, value of 3 to 6, and chroma of 2 to 4. It is sandy loam or fine sandy loam. It is moderately acid to neutral. Both prismatic and platy structure is typically present.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Twig soils have plane or concave slopes in shallow depressions or drainageways on moraines or in swales between drumlins. They formed in a mantle of organic material and underlying loamy material and underlying till that becomes very firm with depth. Slopes range fro m0 to 1 percent. The till is from the Superior Lobe of the Late Wisconsinan glaciation. Mean annual air temperature ranges from 3 to 7 degrees C. Mean annual precipitation ranges from 500 to 675 mm. Frost-free days range from 90 to 135. Elevation above sea level ranges from 350 to 450 meters.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Ahmeek, Brennyville, Giese, Haybrook, Milaca, Mora, Ronneby and Parent soils. Ahmeek, Brennyville, Milaca, Mora and Ronneby soils are all on higher, better drained landscape positions. The poorly drained Haybrook and Parent soils are on slightly higher landscape positions. The very poorly drained Giese soils are in similar positions but do not have an organic surface layer over 20 cm thick.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Very poorly drained. Surface runoff is negligible. The saturated hydraulic conductivity is 42.34 to 141.14 micrometers per second (6 to 20.0 inches) in the organic material; 4.23 to 14.11 micrometers per second (.6 to 2.0 inches per hour) in the next layer and .01 to .42 micrometers per second (.0015 to .06 inches per hour) in the dense till. Perched seasonal high saturation occurs at the surface in spring and fall in normal years. Ponding is also common during periods of snowmelt and heavy rains.
USE AND VEGETATION: Most areas have a native vegetation of lowland hardwoods and aspen or have a cover of sedges and willows. Some are in pasture.
DISTRIBUTION AND EXTENT: MLRA-90A and 93A. Northeastern and East-central Minnesota. Inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Carlton County, Minnesota, 1973.
REMARKS: Diagnostic horizons and features recognized in this pedon are: histic epipedon - the zone from the surface to a depth of 30 cm (Oa1, Oa2, Oe horizons); aquic moisture regime - based on soil saturation to the surface; cambic horizon - the zone from 66 to 122 cm (2Btg and 2Bt horizons); densic contact at 122 cm (2BCd). The Bt and 2Bt horizons due not meet the requirement for an argillic horizon.
The designation of the 2BCd horizon is based on fractures and platy structure in the densic material. Clay and silt translocation can be seen between the horizontal plates when broken apart.
This reddish colored parent material often does not reduce to 2 chroma or less in either the matrix or as redox features when saturated. Studies are ongoing to try and explain this situation.
ADDITIONAL DATA: Refer to MAES Central File Code No. 1108 for results of some laboratory analysis of a representative pedon of this series. Soil Interpretation Record number is MN0165 (obsolete).