LOCATION OULA LAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Hapludalfs
TYPICAL PEDON: Oula very fine sandy loam on a 24 percent slope in a pine forest.
(Colors are for moist soil unless otherwise stated.)
A--0 to 2 inches; dark grayish brown (10YR 4/2) very fine sandy loam; weak medium granular structure; very friable; common medium and fine roots; very strongly acid; clear smooth boundary. (0 to 9 inches)
Bt1--2 to 10 inches; light brownish gray (10YR 6/2) clay; moderate medium subangular blocky structure; firm; common medium and fine roots; common thin faint clay films on faces of peds; extremely acid; gradual smooth boundary.
Bt2--10 to 34 inches; grayish brown (2.5Y 5/2) clay, moderate medium subangular blocky structure; firm; common medium and fine roots, few coarse roots; common faint clay films on faces of peds; extremely acid; gradual smooth boundary.
Bt3--34 to 43 inches; light brownish gray (2.5Y 6/2) clay, weak medium subangular blocky structure; firm; few medium and fine roots; few faint clay films on faces of peds; few slickensides; extremely acid; clear smooth boundary. (Combined thickness of Bt horizon is 25 to 50 inches)
C1--43 to 54 inches; light olive brown (2.5Y 5/4) sandy clay; massive; firm; few medium and fine roots; extremely acid; clear smooth boundary.
C2--54 to 66 inches; light olive brown (2.5Y 5/4) loam; massive; few fine roots; 3 percent by volume sandstone fragments; extremely acid; clear smooth boundary.
C3--66 to 74 inches; light olive brown (2.5Y 5/4) sandy clay loam, massive, friable; 3 percent by volume sandstone fragments; very strongly acid.
TYPE LOCATION: Catahoula Parish, Louisiana: 3.9 miles southwest of Harrisonburg, Louisiana, on La. Hwy. 8; 0.1 mile north on gravel road, 25 feet east of gravel road. Northeast edge Spanish Land Grant Sec. 40, T. 9 N., R. 6 E.
RANGE IN CHARACTERISTICS: Solum ranges from 25 to more than 60 inches thick. Some pedons are underlain by siltstone or sandstone bedrock below 60 inches.
The A horizon has hue of 10YR, value of 3 to 6, and chroma of 2 to 4. Texture is fine sandy loam, very fine sandy loam, silt loam, silty clay loam, or silty clay. Reaction ranges from extremely acid to medium acid.
A thin E horizon is present in some pedons. Color and reaction are the same as the A horizon. Texture is fine sandy loam, very fine sandy loam, or silt loam.
The Bt horizon has hue of 2.5Y or 10YR, value of 5 or 6, and chroma of 2 to 4 or hue of 7.5YR, value of 4 or 5, and chroma of 4 to 6. Mottles in shades of gray or brown range from none to common. Texture is clay, sandy clay, silty clay, or clay loam. Reaction ranges from extremely acid to strongly acid. Fragments of siltstone or sandstone range from 0 to 4 percent by volume. The calcium-magnesium ratio is less than 1.
The C horizon has the same colors as the Bt horizon. It is clay, silty clay, sandy clay, clay loam, silty clay loam, or sandy clay loam. Fragments of soft sandstone or siltstone range from 0 to 4 percent by volume. Reaction ranges from extremely acid to strongly acid.
COMPETING SERIES: These are Colbert, Eastwood, Etoile, Kipling, Lorman, Rayburn, Wilcox, and Woodtell series in the same family and Boswell, Cadeville, Gore, Iredell, Kirvin, Kisatchie, Oktibbeha, and Susquehanna series in similar families. Colbert soils have very-fine lower Bt horizons and are underlain by limestone bedrock. Eastwood soils have high aluminum saturation in the control section, and in addition commonly have browner subsoils. Etoile soils are less acid and have calcium carbonate concretions in the lower part of the control section. Kipling soils have a calcium-magnesium ratio of more than 1.0. Lorman, Rayburn, Wilcox, and Woodtell soils have redder hue in the upper Bt horizon. Boswell, Kirvin, and Susquehanna soils have redder hue and sola thicker than 60 inches. Cadeville and Gore soils have redder hue and mixed mineralogy. Iredell soils are less acid and do not form cracks. Kisatchie soils have rock layers at depths of 20 to 40 inches below the surface. Oktibbeha soils have very-fine control sections and calcium carbonate concretions in the C horizon.
GEOGRAPHIC SETTING: Oula soils are on moderately sloping to steep coastal plains. Slope gradients range from 5 to 30 percent. The parent material is acid clayey and loamy sediment of the Catahoula Formation. The climate is warm and humid. The mean average annual precipitation ranges from 45 to 60 inches. The mean annual temperature ranges from 60 to 70 degrees Fahrenheit.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Kisatchie series and Anacoco, Guyton, Providence, and Smithdale series. Anacoco soils are on lower side slopes and are somewhat poorly drained. Guyton soils are in drainageways, are poorly drained, and have fine-silty control sections. Providence soils have fine-silty control sections and a fragipan. Smithdale soils have fine-loamy control sections and reddish colors.
DRAINAGE AND PERMEABILITY: Oula soils are well drained. Runoff is medium to very rapid. Permeability is very slow.
USE AND VEGETATION: Southern pine and mixed hardwoods. This soil is used almost exclusively for woodland.
DISTRIBUTION AND EXTENT: Southern Coastal plains of Central Louisiana and possibly Mississippi and Texas. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Catahoula Parish, Louisiana; 1983.
REMARKS: These soils have developed in parent material which is reported in geological surveys as having abundant glass, pumice, and bentonite. They were previously included with the Kisatchie series. Colors of 2 chroma in the subsoil are interpreted to be relic colors of the parent material rather than wetness.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon.....0 to 2 inches (A horizon).
Argillic horizon....2 to 43 inches (Bt horizon).