LOCATION COUSHATTA LA+AR OK

Established Series
Rev. WLC:LLL:MJB
01/2017

COUSHATTA SERIES

The Coushatta series consists of very deep, well drained, soils that formed in calcareous, Holocene loamy alluvium derived from sedimentary rock. These soils are on natural levees of the Arkansas River and Red River alluvial plains. Slope ranges from 0 to 3 percent. Mean annual air temperature is about 19 degrees C (66 degrees F), and mean annual precipitation is about 1334 mm (52.5 in).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Fluventic Eutrudepts

TYPICAL PEDON: Coushatta silt loam, on a 0.5 percent slope in a cultivated cotton field; elevation is 39.6 m (130 ft). (Colors are for moist soil unless otherwise stated.)

Ap--0 to 20 cm (0 to 8 in); reddish brown (5YR 4/4) silt loam; weak medium granular structure with weak fine platy structure at 13 to 20 cm (5 to 8 in); friable; many roots; slightly acid; abrupt smooth boundary. (Thickness of the A horizon is 10 to 25 cm [4 to 10 in])

Bw1--20 to 38 cm (8 to 15 in); reddish brown (5YR 4/4) silt loam; weak medium subangular blocky structure; friable; common fine roots; many fine pores; slightly acid; abrupt smooth boundary.

Bw2--38 to 69 cm (15 to 27 in); reddish brown (5YR 4/4) silty clay loam; moderate medium subangular blocky structure; firm; few fine roots; common fine pores; surfaces of peds are dark reddish brown (5YR 3/3); neutral; abrupt smooth boundary. (Combined thickness of the Bw horizon is 26 to 66 cm [10 to 26 in])

C1--69 to 97 cm (27 to 38 in); reddish brown (5YR 4/4) silt loam; massive; friable; common fine pores; slightly alkaline, calcareous; abrupt smooth boundary.

C2--97 to 112 cm (38 to 44 in); reddish brown (5YR 5/4) loamy very fine sand; massive; very friable; moderately alkaline, calcareous; abrupt smooth boundary.

C3--112 to 203cm (44 to 80 in); reddish brown (5YR 4/4) silt loam; massive; friable; few fine strata 0.2 to 3 cm (1/16 to 1 in) thick reddish brown (5YR 4/3) heavy silt loam; moderately alkaline, calcareous.

TYPE LOCATION: Red River Parish, Louisiana; 1.1 mile southeast of Armstead on LA Highway 1, 0.6 mile east northeast on farm road, 200 feet south of road in SW1/4SE1/4 sec. 26, T. 12 N., R. 10 W.

USGS Topographic Quadrangle: Hughes, LA
Latitude: 31 degrees, 59 minutes, 38.5 seconds N
Longitude: 93 degrees, 21 minutes, 47.9 seconds W

Decimal Degrees:
Latitude: 31.99402777 degrees
Longitude: -93.36330555 degrees
Datum: NAD83

UTM Easting: 465681.5 m
UTM Northing: 3539831.4 m
UTM Zone: 15N

RANGE IN CHARACTERISTICS:
Solum thickness: 38 to 91 cm (15 to 36 in)
Depth to cambic horizon: 10 to 25 cm (4 to 10 in)
Depth to calcareous horizon: 38 to 100 cm (15 to 40 in)
Depth to buried horizons: greater than 150 cm (60 in)

Particle-size control section (weighted average)
Clay content: 18 to 30 percent
Sand content: 20 to 30 percent (dominantly very fine sand)
CEC/clay ratio: 0.60 to 0.80

A or Ap horizon:
Hue: 5YR or 7.5YR
Value: 4 or 5
Chroma: 2 to 4
Texture: silt loam, very fine sandy loam or silty clay loam
Reaction: moderately acid to neutral (pH 5.6 to 7.3)

Bw horizon:
Hue: 2.5YR or 5YR
Value: 4 or 5 (if hue of 2.5YR) or 4 to 7 (if hue of 5YR)
Chroma: 4 to 6 (if hue of 2.5YR) or 3 to 6 (if hue of 5YR)
Texture: silt loam or silty clay loam
Clay content: 18 to 30 percent
Effervescence: none
Reaction: slightly acid to moderately alkaline (pH 6.1 to 8.4)

C horizon:
Hue: 2.5YR or 5YR
Value: 4 or 5 (if hue of 2.5YR) or 4 to 7 (if hue of 5YR)
Chroma: 4 to 6 (if hue of 2.5YR) or 3 to 6 (if hue of 5YR)
Texture: loamy very fine sand, very fine sandy loam, silt loam, or silty clay loam
Effervescence: none to slight
Reaction: neutral to moderately alkaline (pH 6.6 to 8.4)

COMPETING SERIES: There are no other series in the same family. Similar series are the Cascilla (MS), Gallion (LA), Idabel (OK), Keo (AR), Ouachita (AR), Norwood (TX), Shellbluff (SC), Roxana (LA), and Severn (OK) series.
Cascilla and Shellbluff soils: have base saturation less than 60 percent at depths of 25 to 75 cm (10 to 30 in)
Gallion soils: have an argillic horizon and are leached of carbonates to greater depths
Idabel soils: have a coarse-loamy control section
Keo, Roxana and Severn soils: have coarse-silty control sections
Ouachita soils: have siliceous mineralogy, and base saturation less than 60 percent at depths of 25 to 75 cm (10 to 30 in)
Norwood soils: are calcareous throughout

GEOGRAPHIC SETTING:
Parent material: calcareous, Holocene age loamy alluvium
Landscape: Arkansas River and Red River alluvial plain
Landform: natural levee
Slope: 0 to 3 percent
Soil moisture: Udic soil moisture regime
Mean annual soil temperature: 18 to 21.2 degrees C (64.5 to 70.1 degrees F)
Mean annual air temperature: 15 to 25 degrees C (59 to 77 degrees F)
Mean annual precipitation: 1069 to 1537mm (45 to 60 in)
Precipitation Pattern: July through September are the driest months, while October through June are the wettest months.
Frost-free period: 219 to 316 days
Elevation: 15 to 64 m (50 to 210 ft)
Thornthwaite annual P-E indices: 81 to 128

GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Keo (AR), Norwood (TX) series, and associated Latanier (LA) and Moreland (LA) series.
Keo and Norwood soils: are on similar positions
Latanier soils: on similar positions, and have clayey surface horizons 50 to 100 cm (20 to 40 in) thick
Moreland soils: are clayey throughout the control section, and on nearby flood plains

DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderate
Runoff: negligible on slopes less than one percent and low on slopes of 1 to 3 percent
Flooding frequency: Most areas are protected by levees. Unprotected areas are subject to occasional or frequent flooding for brief to long durations.
Seasonal high water table: An apparent water table is at depths of 122 to 183 cm (4 to 6 ft) during the months of December to April

USE AND VEGETATION: Used for cultivated crops. Principal crops are cotton, soybeans, corn and small grain. Some areas are used for bermudagrass pasture.

DISTRIBUTION AND EXTENT: Arkansas, Louisiana, and southeastern Oklahoma; Land Resource Region O; MLRA 131B and 131C; the series is of large extent.

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

SERIES ESTABLISHED: McCurtain County, Oklahoma; 1970.

REMARKS: These soils formerly were classified in the Alluvial great soil group.

Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 25 to 100 cm (10 to 40 in) (Bw1, Bw2, C1, and part of C2 horizons)
Ochric epipedon: 0 to 20 cm (0 to 8 in) (Ap horizon)
Cambic horizon: 20 to 69 cm (8 to 27 in) (Bw horizons)

Additional Comments: The assignment of the cation-exchange activity class is supported by Louisiana Agricultural Experiment Station laboratory data number S65La-41-5 from Red River Parish.

Edited 01/2017 (JAD-MJB) Changed to tabular format. Updated pedon description, range in characteristics, and other sections.

ADDITIONAL DATA: Louisiana Agricultural Experiment Station data from type location S65La-41-5 from Red River Parish, Louisiana

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014

National Cooperative Soil Survey
U.S.A.