LOCATION MIDLAND LA+AR TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Chromic Vertic Epiaqualfs
TYPICAL PEDON: Midland silty clay loam--on a broad, nearly level area in a cultivated rice field at an elevation of 10 feet. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silty clay loam, weak fine granular structure; friable, many very fine and fine roots; few fine prominent strong brown (7.5YR 4/6) oxidation stains around roots, moderately acid; clear smooth boundary. (3 to 15 inches thick)
Btg--9 to 19 inches; dark gray (10YR 4/1) silty clay; moderate medium angular blocky structure, firm; many very fine and fine roots; few faint clay films on surfaces of peds; few fine moderately cemented black and brownish iron-manganese concretions; many fine and medium prominent strong brown (7.5YR 5/8) masses of iron accumulation; moderately acid; gradual wavy boundary. (5 to 15 inches thick)
Btkg--19 to 32 inches; gray (10YR 5/1) silty clay; moderate medium angular blocky structure; firm; few fine roots; few faint clay films on surfaces of peds; few fine moderately cemented black and brownish iron-manganese concretions; many coarse prominent strong brown (7.5YR 4/6) masses of iron accumulation; few fine calcium carbonate concretions; neutral; gradual wavy boundary. (10 to 20 inches thick)
Btkssgl--32 to 42 inches; gray (10YR 5/1) silty clay; moderate medium angular blocky structure; firm; few distinct slickensides 6 inches across; few faint clay films on surfaces of peds; few fine moderately cemented black and brownish iron-manganese concretions; many fine prominent strong brown (7.5YR 4/6) and yellowish brown (10YR 5/8) masses of iron accumulation; few fine calcium carbonate concretions; neutral; gradual wavy boundary. (5 to 20 inches thick)
Btkssg2--42 to 80 inches; gray (10YR 6/1) silty clay; weak medium angular blocky structure; firm; few distinct slickensides 6 inches across; few faint clay films on surfaces of peds; many medium and coarse moderately cemented iron-manganese accumulations; many coarse prominent yellowish brown (10YR 5/8) masses of iron accumulation; few fine calcium carbonate concretions; slightly alkaline.
TYPE LOCATION: Acadia Parish, Louisiana; about 1.6 miles northwest of Morse; 0.5 mile north of LA Highway 92; 1600 feet west of Lazy Point Canal, and 75 feet north of parish road P5-13; 2500 feet south and 1750 feet east of the northwest corner of sec. 57, T. 10 S., R. 2 W.; USGS Mermentau, LA. topographic quadrangle; Lat. 30 degrees, 8 minutes, 54 seconds N.; Long. 92 degrees 31 minutes 37 seconds W., NAD 83.
RANGE IN CHARACTERISTICS: The thickness of the solum is more than 80 inches. Slickensides or wedge shaped peds are within 40 inches of the soil surface. COLE values in the upper 20 inches of the B horizon range from about 0.06 to 0.08.
The A, or Ap horizon, has hue of 10YR, value of 4 or 5 and chroma of 1 or 2. Texture is silty clay loam. Reaction ranges from moderately acid to neutral.
The Btg horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 1 or 2. Iron concentrations are in shades of brown, yellow, or olive and range from few to many. Texture is clay, silty clay, or silty clay loam. Reaction ranges from moderately acid to neutral.
The Btkg and Btkssg horizons have hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 1 or 2. Iron concentrations are in shades of brown, yellow, or olive and range from few to many. Texture is clay, silty clay, or silty clay loam. Reaction ranges from neutral to moderately alkaline. Calcium carbonate concretions range from 2 to 5 percent by volume.
The BCg horizon, where present, have the same color, texture, and reaction as the Bg horizons.
COMPETING SERIES: This is the Tensas series in the same family and the similar Bacliff, Baldwin, Beaumont, Crowley, Edna, Judice, Kaplan, Mowata, and Viterbo series. Tensas soils are somewhat poorly drained, formed in Holocene age natural levee sediments, and are underlain with loamy materials. Baldwin soils have formed in Holocene age Mississippi River delta sediments, and are on slightly better drained convex positions on natural leeves. Viterbo soils have red masses of iron accumulation in the B horizons and are somewhat poorly drained. Bacliff, Beaumont, and Judice soils are Vertisols. In addition, Judice soils have a mollic epipedon. Crowley and Edna soils have an abrupt textural change. Kaplan soils have sub-horizons with chroma of more than 2. Mowata soils have a glossic horizon.
GEOGRAPHIC SETTING: Midland soils are on nearly level or slightly concave low depressional areas near drainageways on Pleistocene age terraces. Slopes are less than 1 percent. This soil formed in clayey sediments presumed to have been deposited mainly by the Red River with some influence from the Mississippi River. Mean annual air temperature ranges from 67 to 68 degrees F. Mean annual precipitation ranges from 55 to 65 inches. Frost free days range from 235 to 350. Elevation ranges from 5 to 70 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Basile, Crowley, Judice, Kaplan, and Mowata soils. Basile soils have a fine-silty particle-size control section, have a glossic horizon, and are on flood plains of drainageways. The somewhat poorly drained Crowley and Kaplan soils are on convex ridges and sideslopes at slightly higher elevations. Judice and Mowata soils are in similar positions. Judice soils have a mollic epipedon. Mowata soils have a glossic horizon.
DRAINAGE AND PERMEABILITY: Poorly drained. Very slow permeability. Runoff is negligible. Some areas are subject to occasional or rare flooding for brief periods.
USE AND VEGETATION: Most of this soil is cultivated and used to grow rice and soybeans, rotated with pasture or used for crayfish aquaculture. A few areas are used for corn, grain sorghum, and wheat. Native vegetation was tall prairie grasses.
DISTRIBUTION AND EXTENT: Southwest Louisiana and Southeast Texas (MLRA 150A). The series is of large extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas.
SERIES ESTABLISHED: Acadia Parish, Louisiana; 1948.
REMARKS: Series redescribed and type location moved to site with lab data and centrally located in series province (DRM 1998). Some data indicate these soils may classify as Vertisols.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--0 to 9 inches (Ap horizon).
Argillic horizon--9 to 60 inches (Btg, Btkgl, Btkg2, and Btkg3 horizons).
Aquic moisture regime.
Vertic feature--Slickensides at 32 inches.
ADDITIONAL DATA: Laboratory data on the typifying pedon from Acadia Parish by Louisiana Agricultural Experiment Station (S94LA-001-009).
TAXONOMIC VERSION: Keys to Soil Taxonomy, Ninth Edition, 2003.