LOCATION TOULA LA
Established Series
Rev. JLD; JLL, GRB
12/2014
TOULA SERIES
The Toula series consists of very deep, moderately well drained soils that have a fragipan. Permeability is moderate in the upper part of the subsoil and slow in the fragipan. They formed in a moderately thick mantle of loess over loamy Coastal Plain sediments. Slopes range from 0 to 8 percent.
TAXONOMIC CLASS: Fine-silty, mixed, semiactive, thermic Typic Fragiudults
TYPICAL PEDON: Toula silt loam, on a 1.5 percent slope in young pine woodlands at an elevation of 150 feet (Colors are for moist soil unless otherwise stated).
A--0 to 5 inches; dark grayish brown (10YR 4/2) silt loam; weak fine granular structure; friable; many fine and few coarse roots; moderately acid; abrupt smooth boundary. (3 to 7 inches thick)
BE--5 to 11 inches; light yellowish brown (10YR 6/4) silt loam; common medium distinct yellowish brown (10YR 5/6) mottles; weak fine granular structure; friable; many fine roots; moderately acid; clear smooth boundary. (0 to 7 inches thick)
Bt--11 to 19 inches; yellowish brown (10YR 5/6) silt loam; common medium distinct strong brown (7.5YR 5/6) mottles; moderate medium subangular blocky structure; friable; common fine and few coarse roots; common fine random discontinuous tubular pores; common distinct clay films on faces of peds; moderately acid; clear wavy boundary. (7 to 25 inches thick)
Btx--19 to 24 inches; yellowish brown (10YR 5/4) silty clay loam; moderate very coarse prismatic structure parting to moderate medium subangular blocky; firm and brittle; common fine and few coarse roots in gray seams around peds; few fine random discontinuous tubular pores; many distinct clay films on faces of peds; common medium faint yellowish brown (10YR 5/6) and prominent red (2.5YR 5/6) irregular-shaped masses of oxidized iron; common medium distinct light brownish gray (10YR 6/2) silt loam lenticular clay depletions at top of prisms; moderately acid; clear wavy boundary. (4 to 15 inches thick)
2Btx1--24 to 35 inches; yellowish brown (10YR 5/6) silt loam; weak coarse and very coarse prismatic structure parting to moderate medium subangular blocky; firm and brittle; common coarse roots between prisms; many faint clay films on faces of peds; prisms are dense and brittle and comprise about 70 percent of the cross section; noticeable increase in sand; common medium distinct brown (10YR 5/3) iron depletions, common medium distinct gray (10YR 6/1) silt loam lenticular clay depletions on vertical faces between prisms and dendritic iron depletions on surfaces along root channels, few medium distinct gray (10YR 6/1) iron depletions on horizontal faces of prisms; moderately acid; clear wavy boundary.
2Btx2--35 to 48 inches; yellowish brown (10YR 5/6) silt loam; weak coarse and very coarse prismatic structure parting to moderate medium subangular blocky; firm and brittle; common coarse roots in gray seams around prisms, many faint clay films on faces of peds; prisms are dense and brittle and comprise about 70 percent of the cross section; noticeable sand grains; many medium distinct light olive brown (2.5Y 5/6) irregular masses of oxidized iron, common medium distinct gray (10YR 6/1) silt loam lenticular clay depletions in seams around prisms; moderately acid; clear wavy boundary. (Combined thickness of the 2Btx horizon is 5 to 45 inches.)
2B't--48 to 65 inches; yellowish brown (10YR 5/6) clay loam; weak medium subangular blocky structure; friable; few faint clay films on faces of peds; common medium prominent gray (10YR 6/1) irregular iron depletions and common coarse prominent red (2.5YR 4/6) irregular masses of oxidized iron; moderately acid.
TYPE LOCATION: Tangipahoa Parish, Louisiana; about 2.75 miles northwest of Loranger, 1.25 miles east of State Highway 1054 and 1.25 miles north of Sweetwater Creek, sec. 30, T. 4 S., R. 8. E.
RANGE IN CHARACTERISTICS: The thickness of the solum is greater than 60 inches. Depth to the fragipan ranges from 18 to 38 inches. Depth to redoximorphic depletions having chroma of 2 or less is typically greater than 20 inches, but ranges from 17 to 30 inches. Reaction ranges from very strongly acid to medium acid throughout the solum, except in areas that have been limed. The effective cation exchange capacity of the soil is 20 to 70 percent saturated with exchangeable aluminum to a depth of 30 inches or more. Content of total sand in the particle size control section (Bt horizon) typically is less than 15 percent, but it ranges from 5 to 25 percent. Less than 15 percent of the sand in the particle size control section is fine sand or coarser.
The A or Ap horizon has hue of 10YR, value of 3 to 5, and chroma of 1 to 4. Where the color value is 3, the A horizon is less than 6 inches thick. Texture is silt loam.
The BE horizon, where present, has hue of 7.5YR or 10YR, value of 5 or 6, and chroma of 3 to 8. Texture is silt loam.
The Bt horizon has hue of 7.5YR or 10YR, value of 5 or 6, and chroma of 4 to 8. Masses of iron accumulation in shades of brown range from few to many. Iron depletions in shades of gray, below a depth of 16 inches, are present in some pedons. Texture is silt loam or silty clay loam.
The Btx and 2Btx horizons have the same colors as the Bt horizon. Redoximorphic features in shades of red, yellow, brown and gray range from common to many; or there is no dominant color and is multicolored in these shades. The fragipan has gray vertical seams that form a roughly polygonal pattern of prisms. The matrix of the prisms is very firm and brittle when moist and in the major part of the fragipan and it constitutes more than 60 percent of the volume. Texture is silt loam or silty clay loam in the Btx horizon and silt loam, loam, silty clay loam, or clay loam in the 2Btx horizon. Content of total sand in the 2Btx horizon ranges from 15 to 30 percent. Clay content in the fragipan ranges from 18 to 35 percent.
The 2B't horizon has the same colors and texture as the 2Btx horizon. Brittle bodies are none or few.
COMPETING SERIES: These are the
Lax,
Leadvale,
Shatta, and
Tangi series in the same family and the
Cane,
Loring,
Ora,
Providence, and
Savannah series. Lax soils have 2Btx horizons with 35 to 70 percent chert or quartzite fragments. Leadvale soils have shale fragments in the lower Bt horizon. Shatta soils contain 25 percent or more total sand in the particle size control section and do not have a 2Btx horizon underlying a more silty solum. Tangi soils have a 2Btx horizon with more than 35 percent clay. Cane, Ora, and Savannah soils have a fine-loamy control section. Loring and Providence soils have mixed mineralogy and a base saturation greater than 35 percent at 30 inches below the top of the fragipan.
GEOGRAPHIC SETTING: Toula soils are on stable landforms on broad interstream divides in the Southern Coastal Plain and the Southern Mississippi Valley Silty Uplands. Slopes range from 0 to 8 percent. These soils formed in moderately thick deposits of weathered loess of siliceous mineralogy over loamy Coastal Plain sediments of early Pleistocene Age. The mean annual temperature ranges from 63 to 70 degrees F. The mean annual precipitation ranges from 55 to 65 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Bude,
Calhoun,
Guyton,
Malbis,
Ruston, and
Smithdale soils and the competing
Tangi series. Bude soils have gray mottles in the upper 16 inches of the soil. The Calhoun and Guyton soils are on flat depressional areas. They are poorly drained and do not have a fragipan. Malbis, Ruston, and Smithdale soils are generally on more rolling parts of the landscape. They are fine-loamy and do not have a fragipan.
DRAINAGE AND PERMEABILITY: Moderately well drained. Runoff is slow or medium. The permeability is moderate in the upper part of the B horizon and slow in the fragipan. The soil has a perched water table at a depth of 1.5 to 3.0 feet during December to April.
USE AND VEGETATION: Most of the Toula soils are in pasture or pine woodland. A few areas are cultivated.
DISTRIBUTION AND EXTENT: Louisiana. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Auburn, Alabama.
SERIES ESTABLISHED: Tangipahoa Parish, Louisiana, 1985.
REMARKS: Laboratory data on the typifying pedon were obtained from the Louisiana Agricultural Experiment Station Soil Laboratory, sample S82LA105-16.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 5 inches (A horizon).
Argillic horizon - the zone from 5 to 65 inches (BE, Bt, Btx, 2Btx1, 2Btx2 and 2B't horizons).
Fragipan - the zone from 19 to 48 inches (Btx1, 2Btx1 and 2Btx2 horizons).
National Cooperative Soil Survey
U.S.A.