LOCATION IOTA LAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Hapludalfs
TYPICAL PEDON: Iota silt loam--woodland. (Colors are for moist soil unless otherwise stated.)
A--0 to 3 inches; brown (10YR 4/3) silt loam; weak fine granular structure; slightly hard, friable; many fine and medium roots; strongly acid; abrupt smooth boundary. (3 to 6 inches thick)
E--3 to 7 inches; pale brown (10YR 6/3) silt loam; weak medium platy structure parting to weak fine granular; slightly hard, friable; many fine and medium roots; very strongly acid; abrupt smooth boundary. (0 to 5 inches thick)
Bt--7 to 16 inches; red (2.5YR 4/8) silty clay; moderate medium subangular blocky structure; slightly hard, firm; common fine and medium roots; common very fine and fine tubular pores; few distinct clay films on surface of peds and in pores; very strongly acid; clear wavy boundary.
Btss--16 to 28 inches; yellowish red (5YR 4/6) silty clay; moderate medium subangular blocky structure; hard, firm; few fine and medium roots; common very fine and fine tubular pores; common distinct slickensides with wedge shaped aggregates; common distinct clay films on surface of peds and in pores; common coarse prominent strong brown (7.5YR 5/6) masses of iron accumulation and common medium prominent pale brown (10YR 6/3) iron depletions in matrix; very strongly acid; gradual wavy boundary. (Combined thickness of the Bt horizons range from 16 to 47 inches)
BC--28 to 43 inches; mixed reddish brown (5YR 5/4) and yellowish red (5YR 5/8) silty clay loam; moderate medium subangular blocky structure; hard, firm; few medium distinct yellowish red (5YR 4/6) masses in matrix; stratified pockets of pale brown (10YR 6/3) silt loam; very strongly acid; gradual wavy boundary. (0 to 24 inches thick)
C1--43 to 60 inches; pale brown (10YR 6/3) silty clay loam; massive; firm; many fine and medium round iron-manganese concretions; slightly acid; gradual wavy boundary.
C2--60 to 80 inches; pale brown (10YR 6/3) silt loam; massive; friable; neutral.
TYPE LOCATION: Acadia Parish, Louisiana; about 3 miles north-northeast of Iota to end of Parish Road 436; 0.9 mile northwest on woodland road; 300 feet south of drain and 200 feet northeast in woodland. (1550 feet north and 2800 feet west of the southeast corner of section 12, T. 8 S., R. 2 W.; Latitude 30N, 22, 2; Longitude 92W, 32, 2).
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to 60 inches. Weighted average clay content of the particle-size control section ranges from 40 to 60 percent. Linear extensibility is 6 cm or more between the soil surface and a depth of 40 inches. Slickensides or wedge shaped peds are within 50 inches of the soil surface.
The A or Ap horizon has hue of 10YR, value of 3 to 5, and chroma of 1 to 3. Where value is 3, the A or Ap is less than 6 inches thick. Texture is silt loam or very fine sandy loam. Reaction ranges from very strongly acid to moderately acid.
The E horizon, where present, has hue of 10YR, value of 5 to 7, and chroma of 1 to 3. Texture is silt loam or very fine sandy loam. Reaction ranges from very strongly acid to moderately acid.
The Bt and Btss horizons have hue of 2.5YR or 5YR, value of 3 to 5, and chroma of 4 to 8. Masses of iron accumulation in shades of red or brown and iron depletions in shades if gray range from none to many. Texture is clay or silty clay. Reaction ranges from very strongly acid to neutral.
The BC horizons are mixed or varigated in shades of red, brown, or gray. Texture is clay, silty clay, or silty clay loam. Reaction ranges from very strongly acid to neutral. Calcium carbonate concretions range from none to few.
The C horizon, or Ck horizon where present, have the same color range as the BC horizons. Texture is silty clay loam, silt loam, clay loam, very fine sandy loam, or it is stratified with these textures. Reaction in the upper part ranges from slightly acid to slightly alkaline. In the lower part reaction ranges from neutral to moderately alkaline. Calcium carbonate concretions range from none to common.
COMPETING SERIES: These are the Chickasaw, Colbert, Etoile, Kellison, Oakhurst, Oula, Rayburn, and Woodtell series in the same family. Similiar soils are Boswell, Gore, Forbing, Kolin, and McKamie series. Chickasaw and Rayburn soils are 40 to 60 inches to a paralithic contact. Colbert soils are 40 to 60 inches to a lithic contact with limestone bedrock. Etoile and Kellison soils are 40 to 60 inches to Tertiary age claystone. Oakhurst and Oulia soils are 40 to 60 inches to Catahoula Formation of Tertiary age tuffaceous siltstones or claystones. Woodtell soils are 40 to 60 inches to stratified or thinly bedded loamy and clayey sediments of Tertiary age. Boswell, Forbing, and Gore soils do not have a clay decrease of 20 percent or more from the maximum clay content within 60 inches of the soil surface. Gore soils are gray in the lower Bt horizons and are moderately well drained. Kolin soils have siliceous mineralogy, and have a yellowish matrix. McKamie soils have mixed clay mineralogy.
GEOGRAPHIC SETTING: Iota soils are on stream terraces of Pleistocene age. Slopes range from 3 to 8 percent. These soils formed in red alluvium presumed to be originally from Permian age redbeds and associated sediments. Mean annual temperature is about 67 degrees F. Mean annual precipitation ranges from 55 to 65 inches. Frost free days range from 235 to 300. Elevation ranges from 10 to 80 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Acadiana, Barbary, Basile, Kinder, and Vidrine soils. Acadiana soils are on less sloping areas above drainageways. Vidrine soils are on circular mounded positions usually mapped in a complex with Kinder soils. Kinder and Vidrine soils are on broad, nearly level, higher stream divide landscape positions. Acadiana, Basile, and Kinder soils have glossic horizons. Basile soils are on flood plains of drainageways. Barbary soils are very poorly drained, fluid clays in swamps at lower elevations.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is very slow. Runoff is high on 3 to 5 percent slopes and very high on 5 to 8 percent slopes.
USE AND VEGETATION: Most of the acreage is in woodland, mainly loblolly pine with mixed hardwoods. A small acreage is used for crops and pasture. Main crop grown is soybeans.
DISTRIBUTION AND EXTENT: Southwest Louisiana and possibly southeast Texas (MLRA 150A). The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas.
SERIES ESTABLISHED: Acadia Parish, Louisiana; 2000.
REMARKS: The Iota soils were formerly included with the Acadia, Gore, Muskogee, or McKamie series.
Diagnostic horizons and features in this pedon include:
Ochric epipedon--0 to 7 inches (A and E horizons).
Albic horizon--3 to 7 inches (E horizon).
Argillic horizon--7 to 28 inches (Bt and Btss horizons).
Vertic properties/slickensides--16 to 28 inches (Btss horizon).
Clay decreases with depth- the clay content of the control section decreases by 20 percent (relative) or more from the top of the argillic horizon within a depth of 60 inches.
ADDITIONAL DATA: Laboratory data from Louisiana Agricultural Experiment Station (S94LA-001-4) Acadia Parish, LA.
TAXONOMIC VERSION: Keys to Soil Taxonomy, Ninth Edition, 2003.