LOCATION THIBAUT LA
Established Series
JDS, LK
02/2013
THIBAUT SERIES
The Thibaut series consists of very deep, poorly drained, very slowly permeable soils that formed in clayey alluvium over fine-silty alluvium. These soils are on alluvial flats and on the lower parts of natural levees on the alluvial plain of the Mississippi River and its distributaries. Mean annual air temperature is 20 degrees C. (68 degrees F.) near the type location, and mean annual rainfall is about 1651 mm (65 inches). Slope is dominantly less than 0.5 percent but ranges to 3 percent.
TAXONOMIC CLASS: Clayey over loamy, smectitic over mixed, superactive, nonacid, hyperthermic Vertic Epiaquepts
TYPICAL PEDON: Thibaut clay--in cropland. (Colors are for moist soil unless otherwise stated).
Ap--to 15 centimeters, (0 to 6 inches); dark gray (2.5Y 4/1) clay; moderate medium angular blocky structure; very firm; very sticky; very plastic; common fine roots and few medium roots between peds; common fine prominent brown (7.5YR 5/4) masses of iron accumulation on ped exterior; common medium faint gray (N 5/)redox iron depletions on ped faces; slightly acid; gradual wavy boundary. [8 to 30 centimeters, (3 to 12 inches) thick]
Assg--15 to 30 centimeters, (6 to 12 inches); dark grayish brown (2.5Y 4/2) clay; strong medium angular blocky structure; very firm; very sticky; very plastic; few fine roots in cracks; common fine pores; common prominent intersecting slickensides; many distinct pressure faces on vertical and horizontal faces of peds; common fine prominent brown (7.5YR 5/4) masses of iron accumulation on ped exterior; slightly alkaline; gradual wavy boundary. [0 to 25 centimeters (0 to 10 inches) thick]
Bssg1--30 to 41 centimeters, (12 to 16 inches); gray (2.5Y 5/1) clay; strong medium angular blocky structure; very firm; very sticky; very plastic; few fine roots between peds; few medium prominent light reddish brown (5YR 6/3) horizontal clay lenses less than 1 centimeters thick; few distinct intersecting slickensides; common distinct pressure faces on vertical and horizontal faces of peds; common medium prominent dark yellowish brown (10YR 4/4) masses of iron accumulation on ped exterior; few fine distinct dark gray (5Y 4/1)redox iron depletions on faces of peds and in matrix; slightly alkaline; clear wavy boundary.
Bssg2--41 to 56 centimeters, (16 to 22 inches); gray (2.5Y 6/1) clay; weak medium prismatic structure parting to strong medium subangular blocky; very firm; very sticky; very plastic; many fine roots between peds; common medium prominent reddish brown (5YR 4/4) horizontal clay lenses less than 1 centimeters thick; few distinct intersecting slickensides; common distinct pressure faces on vertical and horizontal faces of peds; common fine prominent brown (7.5YR 4/4) masses of iron accumulation on ped exterior; few fine faint dark gray (2.5Y 4/1) worm casts throughout; common medium distinct gray (10YR 5/1)redox iron depletions on faces of peds and in matrix; slightly alkaline; clear wavy boundary.
Bssg3--56 to 76 centimeters, (22 to 30 inches); gray (2.5Y 5/1) silty clay; weak medium prismatic structure; very firm; very sticky; very plastic; few fine roots between peds; common medium prominent light reddish brown (5YR 6/3) horizontal lenses less than 1 centimeters thick; few distinct intersecting slickensides; common distinct pressure faces on vertical and horizontal faces of peds; common medium prominent strong brown (7.5YR 5/6) masses of iron accumulation on ped exterior; common medium prominent strong brown (7.5YR 4/6) masses of iron accumulation on ped exterior; common fine faint gray (N 6/)redox iron depletions on faces of peds and in matrix; moderately alkaline; clear wavy boundary. [Combined thickness of the Bssg horizons is 25 to 89 centimeters, (10 to 35 inches) thick]
2Bg--76 to 99 centimeters, (30 to 39 inches); grayish brown (2.5Y 5/2) silt loam; moderate medium angular blocky structure; friable; nonsticky; nonplastic; common fine pores; common very fine prominent reddish brown (5YR 4/4) horizontal silt lenses less than 1 centimeters thick; few fine prominent strong brown (7.5YR 4/6) masses of iron accumulation on ped exterior; common medium rounded strong brown (7.5YR 4/6) iron-manganese nodules throughout; common medium faint gray (N 6/) redox iron depletions on ped exterior; moderately alkaline; abrupt wavy boundary. [0 to 30 centimeters, (0 to 12 inches) thick]
2Cg1--99 to 132 centimeters, (39 to 52 inches); grayish brown (2.5Y 5/2) silt loam; massive; friable; nonsticky; nonplastic; common fine pores; common medium prominent yellowish brown (10YR 5/6) masses of iron accumulation on ped exterior; common medium faint light olive brown (2.5Y 5/3) masses of iron accumulation on faces of peds and in matrix; few medium faint gray (2.5Y 6/1) redox iron depletions on faces of peds and in matrix; moderately alkaline; clear wavy boundary. [25 to 152 centimeters, (12 to more than 60 inches) thick
3Cg2--132 to 150 centimeters, (52 to 59 inches); gray (5Y 5/1) silty clay loam; strong medium angular blocky structure; firm; slightly sticky; slightly plastic; common fine pores; common medium prominent yellowish brown (10YR 5/6) masses of iron accumulation on ped exterior; common medium distinct light olive brown (2.5Y 5/3) masses of iron accumulation on faces of peds and in matrix; few medium faint gray (N 5/) iron depletions on ped exterior; moderately alkaline; clear wavy boundary.
3Cg3--150 to 180 centimeters, (59 to 71 inches); gray (2.5Y 5/1) silty clay; strong fine subangular blocky structure; very firm; very sticky; very plastic; common fine pores; common medium irregular brownish yellow (10YR 6/8) slightly hard iron-manganese nodules throughout; common medium irregular brownish yellow (10YR 6/6) slightly hard iron-manganese nodules throughout; slightly alkaline; clear wavy boundary.
3Cg4--180 to 196 centimeters, (71 to 77 inches); gray (N 5/) silty clay; strong medium subangular blocky structure; very firm; very sticky; very plastic; common fine pores; common medium irregular brownish yellow (10YR 6/6) and brownish yellow (10YR 6/8) slightly hard iron-manganese nodules throughout; slightly alkaline; clear wavy boundary.
4Cg5--196 to 216 centimeters, (77 to 85 inches); gray (2.5Y 5/1) silty clay; moderate medium angular blocky structure; very firm; very sticky; very plastic; common fine pores; common medium prominent yellowish brown (10YR 5/6) masses of iron accumulation on faces of peds and in matrix; few fine prominent strong brown (7.5YR 5/8) masses of iron accumulation on ped exterior; slightly alkaline.
TYPE LOCATION: Ascension Parish, Louisiana; from the intersection of Louisiana Highway 18 and Louisiana Highway 80 near Lemannville approximately 1.5 km (0.96 mile) north on Highway 18, about 1.6 km [1 mile, 1608 meters (5,360 feet)] southwest of Highway 18 on an improved road, and 15 meters (50 feet) southeast into a field; 135 meters (450 feet) east of the northwest corner of Spanish Land Grant 109, T. 11S., R. 15E. USGS Donaldsonville, Louisiana 7.5 minute topographic quadrangle; 30 degrees, 6 minutes, 1.78 seconds N. Latitude; 90 degrees, 55 minutes, 55.85 seconds W.; NAD 1983.
RANGE IN CHARACTERISTICS:
Solum thickness: 51 to 152 centimeters, (20 to 60 inches)
Depth to the contrasting fine-silty discontinuity: 51 to 102 centimeters, (20 to 40 inches). Another discontinuity that is clayey is below a depth of 127 centimeters (50 inches) in some pedons.
Reaction: moderately acid to moderately alkaline throughout
Ap or Assg horizon:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 1 or 2; or it is neutral with value of 4
Combined thickness: less than 12 inches, where value is 3.
Texture: silty clay or clay, some pedons have a surface mantle of recent overwash material of stratified silt loam or silty clay loam
Bssg horizon:
Hue: 10YR to 5Y
Value: 4 to 6
Chroma: 1 or 2; or it is neutral with value of 4 to 6
Redoximorphic features: Masses of iron accumulation and iron depletions in shades of brown and gray throughout the Bssg horizon. Some pedons have thin lenses or seams of material with hue of 5YR or redder within the Bssg horizon
Texture: silty clay or clay
2Bg and 2Cg horizons:
Hue: 10YR to 5Y
Value: 3 to 6
Chroma: 1 or 2 or they are neutral with value of 4 to 6
Texture: silt loam, loam, silty clay loam, or very fine sandy loam within a depth of 40 inches, and included, fine sandy loam or loamy fine sand below 40 inches in some pedons
3Cg or 4Cg horizons, where present:
Hue: 2.5Y to 5BG
Value: 3 to 6
Chroma: 1 or less
Texture: silty clay loam, silty clay, or clay
COMPETING SERIES: There are no other series in the same family.
GEOGRAPHIC SETTING:
Landform: flood plains of the lower Mississippi River and its distributaries in the Southern Mississippi Valley Alluvium Major Land Resource Area 131A.
Parent mater: formed in clayey alluvium over fine-silty alluvium
Slopes: less than 3 percent.
Mean annual air temperature: ranges from 18.3 to 23.9 degrees C. (65 to 75 degrees F)
Mean annual precipitation: 1397 to 1778 mm (55 to 70 inches).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Cancienne,
Gramercy, and
Schriever series.
Cancienne soils are on slightly higher natural levee positions and are fine-silty throughout.
Gramercy and
Schriever soils are on slightly lower positions and are clayey throughout the upper 40 inches.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: poorly drained
Runoff is slow.
Saturated hydraulic conductivity: low in the clayey A and Bssg horizons, and moderately high in the loamy 2Bg and 2C horizons.
Episaturation: 0 to 15 centimeters (0 and 6 inches), and in the loamy layers below the discontinuity during the months of January through April during most years; and they are moist in the Bg and Bssg horizons.
Flooding: Rare to frequent flooding for brief to long periods in areas not protected by levees.
USE AND VEGETATION: Most areas of Thibaut soils are cultivated to sugarcane, soybeans, cotton, small grains, corn, hay, or pasture. A smaller amount of the total acreage is in bottomland hardwoods. In wooded areas, the overstory generally consists of cherrybark oak, eastern cottonwood, green ash, nuttall oak, sweetgum, American sycamore, American and cedar elm, water oak, Sugarberry, pecan, and water hickory.
DISTRIBUTION AND EXTENT: South-central Louisiana, Southern Mississippi River Alluvium, MLRA 131A. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: AUBURN, ALABAMA
SERIES PROPOSED: Ascension Parish, Louisiana, 1996. Thibaut soils formerly were included with the Tunica series.
REMARKS: Diagnostic horizons and features in this pedon include:
Ochric epipedon-----------0 to 30 centimeters, (0 to 12 inches) (Ap & Assg horizon)
Cambic horizon------------30 to 99 centimeters, (12 to 39 inches) (Bssg horizons)
Fine-silty discontinuity---76 centimeters (30 inches) (top of 2Bg horizon)
Aquic conditions---------- 0to 15 centimeters, (0 to 6 inches) (episaturation and redoximorphic features in the Ap horizon)
Intersecting slickensides-15 to 76 centimeters (6 to 30 inches) (Assg & Bssg horizons)
ADDITIONAL DATA: Characterization data for this pedon were run at the NSSL, Lincoln, Nebraska; Pedon no.S95LA-005-001
National Cooperative Soil Survey
U.S.A.