Official Series Description - ALLEMANDS Series (2022)

LOCATION ALLEMANDSLA+TX

Established Series
Rev. WLC-CLN
10/2018


The Allemands series consists of very deep, very poorly drained, soils that are rapidly permeable in the organic materials and very slowly permeable in the underlying clay horizons. These soils are on the landward side of low coastal freshwater marshes and formed in decomposed herbaceous material over alluvial sediments. Slope ranges from 0 to 0.2 percent.

TAXONOMIC CLASS: Clayey, smectitic, euic, hyperthermic Terric Haplosaprists

TYPICAL PEDON: Allemands mucky peat--freshwater marsh. (Colors are for wet soil unless otherwise stated.)

Oa1--0 to 2 inches; brown (10YR 4/3), muck; structureless, massive; nonsticky, nonplastic; 40 percent fiber, unrubbed; 15 percent fiber, rubbed; many fine roots throughout; moderately alkaline; clear smooth boundary.

Oa2--2 to 4 inches; dark grayish brown (10YR 4/2) muck; structureless, massive; nonsticky, nonplastic; 30 percent fiber, unrubbed; 10 percent fiber, rubbed; many fine roots throughout; moderately alkaline; clear smooth boundary.

Oa3--4 to 32 inches; very dark gray (10YR 3/1) muck; structureless, massive; nonsticky, nonplastic; 30 percent fiber, unrubbed; 10 percent fiber, rubbed; many fine roots throughout; moderately alkaline; gradual wavy boundary (combined thickness of the organic layers is 16 to 51 inches).

Cg1--32 to 65 inches; gray (5Y 5/1) clay; structureless, massive; very sticky, moderately plastic; moderately alkaline; diffuse boundary.

Cg2--65 to 80 inches; dark gray (N 4/) very fine sandy loam; structureless, massive; nonsticky, nonplastic; moderately alkaline.

TYPE LOCATION: St. John the Baptist Parish, Louisiana; located 0.3 mile west of Lac Des Allemands on Bayou Lassene, then 1,500 feet southwest on canal, and 100 feet due north of canal; Latitude 29 degrees, 57 minutes, 5.37 seconds N.; Longitude 90 degrees, 37 minutes, 53.43 seconds W., Lower Vacherie, Louisiana USGS 7.5 Minute Quadrangle.

RANGE IN CHARACTERISTICS:
Solum thickness: Organic material thickness is 16 to 51 inches
Redoximorphic features: Gleyed matrix in the mineral layers
Other distinctive soil features: The organic materials are dominantly from herbaceous materials.
Concentrated minerals: Electrical conductivity (EC) ranges mainly from 0 to about 2 dS/m in the upper 20 inches and 0 to 4 dS/m from 20 to 80 inches in most years. The EC varies lower or higher during periods of excess rainfall or extended droughts.

Surface tier of the Oa horizon:
Color--Hue of 7.5YR or 10YR, value of 2 to 4, and chroma of 1 to 3; or is neutral with value of 3 or 4.
Redoximorphic features-- None
Texture--Muck; the mineral content ranges from 15 to 40 percent and it is dominantly clay but includes thin strata of loamy material in some pedons. A thin clayey overwash is on the surface of some drained pedons.
Other features--After rubbing, the surface tier has a fiber content ranging from less than 1/10 to more than 4/10 of the organic volume, where there is no mineral horizon more than 16 inches thick with an upper boundary in the 12 to 36 inch zone. Where a mineral layer has an upper boundary in the 16 to 36 inch zone, the fiber content of the 12 inch surface layer is such that a dominant part of the organic portion of the profile will have fiber content of less than 1/10 the organic volume.
Reaction--Strongly acid to moderately alkaline under natural conditions; or extremely acid to slightly acid under drained conditions.
Thickness--12 inches

Subsurface tier of the Oa horizon:
Color--Hue of 5YR to 10YR, value of 2 to 4, and chroma of 1 to 3.
Redoximorphic features--None
Texture--Muck; some pedons have thin mineral layers in this tier.
Other features--The dominant layers of the subsurface tier have a fiber content of less than 1/10 the organic volume. Mineral content ranges from 20 to 50 percent.
Reaction--Strongly acid to moderately alkaline under natural conditions; or extremely acid to slightly acid under drained conditions.
Thickness--4 to 24 inches

Bottom tier of the Oa horizon: (where present)
Color--Hue of 5YR to 10YR, value of 2 to 4, and chroma of 1 to 3.
Redoximorphic features--None
Texture--Muck; some pedons have thin mineral layers in this tier.
Other features--The dominant layers of the bottom tier have a fiber content of less than 1/10 the organic volume. Mineral content ranges from 20 to 50 percent.
Reaction--Strongly acid to moderately alkaline under natural conditions; or extremely acid to moderately alkaline under drained conditions.
Thickness--0 to 14 inches

Ag horizon: (where present)
Color--Hue of 10YR, 2.5Y, or 5Y, value of 2 to 5, and chroma of 1
Redoximorphic features--Gleyed matrix
Texture--Clay or mucky clay containing from 60 to 95 percent clay.
Other features--None
Reaction--Slightly acid to moderately alkaline under natural conditions; or extremely acid to slightly alkaline under drained conditions.
Thickness--0 to 20 inches

Cg horizon:
Color--Hue of 10YR to 5Y, 5G, or 5GY, value of 3 to 6, and chroma of 1 or 2; or is neutral with value of 3 to 6
Redoximorphic features--Gleyed matrix
Texture--Clay or mucky clay to fine sandy loam or mucky sandy loam
Other features--Calcium carbonate concretions range from none to few. Iron-manganese concentrations range from none to few.
Reaction--Slightly acid to moderately alkaline under natural conditions; or extremely acid to moderately alkaline under drained conditions.

COMPETING SERIES: These are Bellpass, Bessie, Carlin, and Clovelly series in the same family, and the Barbary, Belhaven, Dare, Dorovan, Gentilly, Harris, Kenner, Lafitte, Larose, Mattamuskeet, Maurepas, Pamlico, Ponzer, and Pungo series in closely related families. Bellpass, Bessie, and Clovelly soils have salinity of more than 3 dS/m in the control section. Carlin soils have a water layer at least 6 inches thick below the surface tier. Barbary, Gentilly, Harris, and Larose soils are mineral soils. Belhaven, Dare, Dorovan, Mattamuskeet, Pamlico, Ponzer, and Pungo soils have pH value less than 5.5 in all parts of the control section. Dare, Dorovan, Kenner, Lafitte, Maurepas, and Pungo soils have organic materials with a combined thickness of more than 51 inches. Also, Pungo soils have horizons in the subsurface layer with less decomposed fiber. Belhaven, Matamuskeet, Pamlico, and Ponzer soils have coarser textured mineral horizons underlying the organic material.

GEOGRAPHIC SETTING: Allemands soils occur on the landward side of the low coastal freshwater marshes. They are almost continuously flooded unless drained. The soil formed in 16 to 51 inches of well-decomposed organic material overlying clays. The climate is humid subtropical. The mean annual air temperature ranges from 70 to 72 degrees F., and the mean annual precipitation is about 64 inches near the type location.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Carlin soils; the closely related Barbary, Harris, Kenner, Larose soils; and also Caplin, Ged, Gentilly, Maurepas, and Zummo soils. Caplin and Maurepas soils have surface organic materials more than 51 inches thick. Ged soils are Aqualfs. Gentilly and Zummo soils have an organic surface less than 16 inches thick.

DRAINAGE AND PERMEABILITY: Very poorly drained. Internal drainage is none and permeability is rapid in the organic material and very slow in the underlying clay horizons. The water level is 1 foot above the surface to 0.5 foot below the surface. During tropical storms, floodwaters are up to 4 feet deep or more. In drained areas, the water table is regulated by a system of levees and pumps and averages 1 to 4 feet below the surface.

USE AND VEGETATION: These soils are used for wildlife habitat. Some areas are drained and used for grazing and crop production. The vegetation consists dominantly of maidencane, bulltongue, cattail, bulrush, cutgrass, and longtom.

DISTRIBUTION AND EXTENT: Coast Marsh (MLRA 151) area of Louisiana, southeast Texas, and possibly Alabama and Mississippi. The series is of large extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: AUBURN, ALABAMA

SERIES ESTABLISHED: St. John the Baptist Parish, Louisiana; 1971.

REMARKS: The type location pedon was moved to a more representative location in St. John the Baptist Parish in 2004 based on data from the updated survey. Diagnostic horizons and features recognized in this pedon are:
Histic epipedon - 0 to 32 inches (Oa horizons).
Aquic conditions - Saturated organic soil materials throughout the upper part, and gleyed matrix in the mineral soil materials below that.
Ecological Site: Fresh Organic Marsh.

ADDITIONAL DATA: Louisiana State University lab data (S94LA-109-020, 024, and 030) from Terrebonne Parish.

TAXONOMIC VERSION: Keys to Soil Taxonomy, Ninth Edition, 2003.

National Cooperative Soil Survey
U.S.A.

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