LOCATION MARNA MN+IA
Established Series
Rev. ROP-TCJ-AGG
03/2014
MARNA SERIES
The Marna series consists of very deep poorly drained soils that formed in a clayey glacial lacustrine mantle and the underlying calcareous loamy glacial till on lacustrine plains and ground moraines. These soils have slow permeability. Their slopes range from 0 to 2 percent. Mean annual precipitation is about 28 inches. Mean annual air temperature is about 47 degrees F.
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Endoaquolls
TYPICAL PEDON: Marna silty clay, on a nearly level slope, on a lacustrine mantled till plain, in a cultivated field. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; black (N 2/0) silty clay loam, very dark gray (N 3/0) dry; moderate fine subangular blocky structure; firm; about 2 percent gravel, mostly shale; many worm casts; slightly acid; gradual smooth boundary.
A--9 to 15 inches; black (N 2/0) silty clay loam, very dark gray (N 3/0) dry; moderate fine subangular blocky structure; very firm; about 2 percent gravel, mostly shale; many worm casts; slightly acid; clear wavy boundary. (Combined thickness of the A horizon is 12 to 24 inches.)
AB--15 to 20 inches; very dark gray (10YR 3/1) silty clay, dark gray (10YR 4/1) dry; moderate fine subangular blocky structure; very firm; about 2 percent gravel, mostly shale; common worm casts; slightly acid; gradual smooth boundary. (0 to 10 inches thick)
Bg1--20 to 26 inches; dark grayish brown (2.5Y 4/2) clay, faint very dark grayish brown (2.5Y 3/2) coatings on peds; moderate fine subangular blocky structure; very firm; few fine prominent olive (5Y 5/6) Fe concentrations; about 2 percent gravel, mostly shale; common rounded sand size shale particles; slightly acid; gradual smooth boundary.
Bg2--26 to 32 inches; olive gray (5Y 5/2) clay; faint olive gray (5Y 4/2) coatings on peds; moderate medium prismatic structure parting to moderate medium subangular blocky; firm; many fine prominent light olive brown (2.5Y 5/4) and many fine faint olive (5Y 5/3) Fe concentrations; about 2 percent gravel, mostly shale; neutral; gradual smooth boundary. (Combined thickness of the Bg horizon is 8 to 20 inches.)
2Bg--32 to 41 inches; olive gray (5Y 4/2) clay loam; moderate medium prismatic structure parting to moderate fine subangular blocky; firm; many fine prominent light olive brown (2.5Y 5/6) Fe concentrations and many fine faint dark olive gray (5Y 3/2) Fe depletions; about 5 percent gravel; few very dark gray (10YR 3/1) root channel fillings; neutral; abrupt wavy boundary. (0 to 12 inches thick)
2Bkg--41 to 60 inches; olive gray (5Y 4/2) loam; weak medium subangular blocky structure; friable; many fine faint olive gray (5Y 5/2) Fe depletions and many fine prominent light olive brown (2.5Y 5/6) Fe concentrations; about 5 percent gravel; few masses of light gray (10YR 7/2) lime; strongly effervescent; slightly alkaline.
TYPE LOCATION: Blue Earth County, Minnesota; about .75 miles south of Amboy; located about 10 feet east and 5 feet north of the southwest corner of section 23, T. 105 N., R. 28 W.; USGS Amboy topographic quadrangle; lat. 43 degrees 52 minutes 38 seconds N. and long. 94 degrees 10 minutes 06 seconds W., NAD 83.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 16 to 24 inches in thickness. Depth to carbonates ranges from 26 to 48 inches. Depth to horizons in loam or clay loam glacial till ranges from 24 to 40 inches. Content of rock fragments in the upper mantle ranges from 0 to 5 percent dominated by soft shale. Rock fragments of mixed lithology range from 2 to 10 percent in the glacial till. The 10 to 40 inch particle-size control section averages between 35 and 60 percent clay and between 10 and 30 percent sand.
The A horizon has hue of 10YR to 5Y or is neutral, value of 2 or 3, and chroma of 0 or 1. It is silty clay loam, silty clay, or clay. It is firm to very firm. It is slightly acid or neutral.
The Bg horizon has hue of 5Y or 2.5Y, value of 4 or 5, chroma of 1 or 2. It has few to many redoximorphic features. It is slightly acid or neutral. It is silty clay loam, silty clay or clay.
The 2Bg or 2BCg horizons are loam or clay loam, with color similar to the Bg horizon. They are firm or friable. They are slightly alkaline or neutral.
The 2Bkg horizon has hue of 2.5Y or 5Y, value of 4 or 5, and chroma of 1 or 2. It is loam or clay loam. It has bulk density of 1.40 to 1.60 gm/cc. It has 20 to 30 percent clay and 30 to 45 percent sand. It is friable. It is slightly alkaline or moderately alkaline. A thin C horizon with texture of silty clay loam, silty clay or clay is within 60 inches in some pedons.
COMPETING SERIES: These are in the
Cosmos and
Waldorf series. When previously classified in the Typic Haplaquolls subgroup, other competing series were
Chequest,
Kalona,
Lanyon, and
Streator. Cosmos soils have moist bulk densities greater than 1.6 gm/cc in the lower part of the series control section. Waldorf soils have less than 10 percent sand throughout the series control section. Chequest, Kalona, and Streator soils do not have carbonates within depths of 48 inches. Lanyon soils have carbonates within depths of 20 inches.
GEOGRAPHIC SETTING: Marna soils have slightly concave to slightly convex slopes on lake plains and clayey-mantled ground moraines. Their slopes range from 0 to 2 percent. They formed primarily in 24 to 40 inches of clayey glacial lacustrine sediments and calcareous loamy glacial till. The deposits are late Wisconsinan in age. The climate is humid continental with warm summers and cold winters. Mean annual air temperature ranges from 45 to 50 degrees F. Mean annual precipitation ranges from 26 to 32 inches. Elevation ranges from 900 to 1200 feet above sea level. Frost-free period ranges from 124 to 172 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Kamrar,
Guckeen,
Brownton, and
Lura soils which are members of a hydrosequence with the Marna soils. The well drained Kamrar and the moderately well drained and somewhat poorly drained Guckeen soils are on backslopes, shoulders and summits. The poorly drained calcareous Brownton soils are on nearby low rises and rims of depressions. The very poorly drained Lura soils are in depressions and swales.
DRAINAGE AND PERMEABILITY: Poorly drained. The apparent seasonal high water table is at 1 to 2.5 feet at some time during November to June in normal years. Surface runoff is slow. Permeability is slow.
USE AND VEGETATION: Mostly cultivated with corn and soybeans being the principal crops. Native vegetation is predominantly wet-site tall prairie species such as prairie cordgrass, switchgrass, big bluestem, wooly sedge, giant goldenrod and Canada goldenrod.
DISTRIBUTION AND EXTENT: South-central Minnesota and north-central Iowa. Moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Faribault County, Minnesota, 1950.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - the zone from the surface to 20 inches (Ap, A, and AB horizons);
Cambic horizon - the zone from 20 to 41 inches (Bg1, Bg2, and 2BCg horizons);
Aquic suborder - 2 chroma matrix and redoximorphic concentrations immediately below the mollic epipedon.
ADDITIONAL DATA: Refer to NSSL No. S69MN71 for results of some laboratory analyses of a typical pedon of this series.
National Cooperative Soil Survey
U.S.A.