LOCATION NATCHITOCHES            LA

Established Series
Rev CLB:WLC
12/2022

NATCHITOCHES SERIES

The Natchitoches series consists of well drained, very slowly permeable soils that formed in sediments high in content of glauconite. These soils are on uplands in the southern coastal plains. Slopes range from 1 to 12 percent.

TAXONOMIC CLASS: Very-fine, smectitic, thermic Vertic Hapludalfs

TYPICAL PEDON: Natchitoches sandy clay loam--forest. (Colors are for moist soil unless otherwise stated.)

A--0 to 4 inches; dark reddish brown (5YR 3/2) sandy clay loam; weak fine granular structure; friable; common medium roots; strongly acid; clear wavy boundary. (1 to 6 inches thick)

Bt1--4 to 11 inches; reddish brown (5YR 4/4) clay; few fine distinct red (2.5YR 4/6) mottles; moderate fine subangular blocky structure; very firm; common fine roots; thick continuous clay films; prominent greenish glauconite sand; very strongly acid; clear wavy boundary. (6 to 15 inches thick)

Bt2--11 to 38 inches; red (10R 4/6) clay; many medium prominent olive (5Y 5/3) mottles; moderate medium subangular blocky structure; very firm; few fine roots; thin patchy clay films on faces of peds; many slickensides that do not intersect; about 20 percent greenish glauconite sand; very strongly acid; clear wavy boundary. (10 to 20 inches thick)

C1--38 to 46 inches; yellowish brown (10YR 5/6) and light olive brown (2.5Y 5/4) clay with common fine distinct light brownish gray (2.5Y 6/2) mottles; massive; very firm; common slickensides that do not intersect; about 30 percent greenish glauconite sand; slightly acid; clear wavy boundary. (6 to 15 inches thick)

C2--46 to 63 inches; light yellowish brown (2.5Y 6/4) clay with common fine distinct strong brown (7.5YR 5/6) and yellowish brown (10YR 5/6) mottles; massive; very firm; about 30 percent greenish glauconite sand; common soft masses of calcium carbonate; common medium calcium carbonate concretions; neutral.

TYPE LOCATION: Natchitoches Parish, Louisiana; about .5 mile west of the Chestnut Post Office; 225 feet south of Parish Road 479; sec. 31, T. 13 N., R. 6 W.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 30 to 50 inches.

The A or Ap horizon has hue of 5YR, value of 2 or 3, and chroma of 2 or 3; hue of 2.5YR, value of 2 to 5; or hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 or 3. It is fine sandy loam, sandy loam, or sandy clay loam. Reaction is strongly acid to slightly acid.

The Bt horizon has hue of 5YR, value of 4, and chroma of 3 to 6; hue of 2.5YR, value of 4; or hue of 10R, value of 4, and chroma of 6 to 8. It is clay or sandy clay. Reaction is very strongly acid to medium acid. Olive or brownish mottles are common to many in some subhorizons.

The BC horizon, where present, has the same color range as the Bt horizon, or it is mottled in shades of brown, olive, gray, or red. Glauconitic sand makes up about 20 to 40 percent. The texture and reaction range is the same at the Bt horizon.

The C horizon is mottled in shades of brown, olive, gray, or red. It is clay or sandy clay. Reaction is medium acid to mildly alkaline. Greenish glauconite sand is prominent throughout. Calcium carbonate accumulations and carbonate concretions range from none to common in the C horizon.

COMPETING SERIES: These are the Colbert, Oktibbeha, and Vaiden series in the same family and the Boswell, Cadeville, Hallsummit, and Susquehanna series. All of these soils do not have appreciable amounts of glauconite in the Bt and C horizons.

GEOGRAPHIC SETTING: The Natchitoches soils are on nearly level to sloping southern coastal plains. Slope gradients range from 1 to 12 percent. The soil formed from thick deposits of sediments high in glauconitic sand in the Cook Mountain Formation. Near the type location the mean annual temperature is about 66 degrees F, and the average annual rainfall is about 50 inches near the type location.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Boswell, Hallsummit, and Susquehanna series.

DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; very slow permeability.

USE AND VEGETATION: Mostly woodland. A few areas are in pasture.

DISTRIBUTION AND EXTENT: Louisiana and possibly Arkansas and Texas. The series is of minor extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Natchitoches Parish, Louisiana; 1921.

REMARKS: The Natchitoches series is placed in the Hapludalfs great group rather than Paleudalfs, because the lower part of the pedon does not have red colors. Also, the high content of clay in the C horizons is inherent to the parent material and not the result of clay movement. Data is available in sample number 372LA-35-1 by the National Soil Survey Laboratory and ample number 374LA-69-1 by the Louisiana State University laboratory.

Diagnostic horizons and features recognized in this pedon are:

Argillic horizon - the Bt horizon from 4 to 38 inches.

Vertic properties - has the necessary cracks, cole, and clay content for the subgroup.

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National Cooperative Soil Survey
U.S.A.