LOCATION ROBERTSDALE AL+FL GAEstablished Series
TAXONOMIC CLASS: Fine-loamy, siliceous, semiactive, thermic Plinthaquic Paleudults
(Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; very dark gray (10YR 3/1) fine sandy loam; weak medium platy structure parting to weak medium granular; friable; common fine iron concretions; moderately acid; abrupt smooth boundary. (4 to 9 inches thick)
EBc--6 to 12 inches; light yellowish brown (2.5Y 6/4) fine sandy loam; few fine faint yellowish brown and strong brown mottles; weak coarse subangular blocky structure; friable; common fine iron concretions; weak clay bridging of sand grains; few small areas of clean sand grains; very strongly acid; clear wavy boundary. (3 to 12 inches thick)
Btc--12 to 21 inches; pale brown (10YR 6/3) loam; common medium distinct strong brown (7.5YR 5/6) and light gray (2.5Y7/2), and few medium faint yellowish brown (10YR 5/8) mottles; weak coarse subangular blocky structure; friable; common fine and medium iron concretions; few thin patchy clay films; brown areas have sand grains bridged with clay; many clean sand grains in gray areas; 3 to 5 percent by volume of plinthite; strongly acid; gradual wavy boundary. (3 to 14 inches thick)
Btcg--21 to 29 inches; light gray (2.5Y 7/2) sandy clay loam; many medium and coarse distinct yellowish brown (10YR 5/6) mottles; coarse prismatic structure; parting to weak coarse subangular blocky; firm; common fine and medium iron concretions; few thin patchy clay films on faces of peds; sand grains strongly bridged with clay; 20 percent plinthite nodules; strongly acid; gradual wavy boundary. (8 to 16 inches thick)
Btvg1--20 to 43 inches; light gray (2.5Y 7/2) sandy clay loam; common medium faint gray (10YR 6/1) and many medium distinct yellowish brown (10YR 5/8) mottles; coarse prismatic structure parting to weak coarse blocky; firm; common fine vesicular pores lined with clay; common fine and medium hard iron concretions; thin patchy clay films on faces of peds; few uncoated sand grains in gray matrix; 15 percent plinthite nodules; strongly acid; clear wavy boundary. (12 to 30 inches thick)
Btvg2--43 to 68 inches; mottled yellowish brown (10YR 5/6) and red (2.5YR 4/8) sandy clay loam; weak coarse prismatic parting to coarse platy structure parting to weak medium blocky; very firm; seams between prisms filled with light gray (10YR 7/1) fine sandy loam; many vesicular pores lined with clay; common medium and coarse iron concretions; thin patchy clay films on faces of peds; 10 percent plinthite nodules; moderately acid; clear wavy boundary. (15 to 30 inches thick)
Cg--68 to 74 inches; mottled red (10R 4/8), brownish yellow (10YR 6/8), and light gray (10YR 7/1) light clay loam; massive; friable; moderately acid.
TYPE LOCATION: Baldwin County, Alabama. Approximately 1 mile south and 1 mile east of the south edge of Robertsdale, about 230 feet north on gravel road, and 25 feet east of center of road in the SW1/4, SW1/4, sec. 8, T. 6 S., R. 4 E.
RANGE IN CHARACTERISTICS: Solum thickness and depth to bedrock is more than 60 inches. Reaction ranges from very strongly acid to moderately acid except where the surface has been limed. Silt content in the control section ranges from 20 to 50 percent.
The A horizon has hue of 10YR, values of 2 through 4, and chroma 1 or 2. It is fine sandy loam or loam. Iron concretions up to 7.5 cm in diameter range from 4 to 12 percent by volume.
The EB and Btc horizons have hue of 10YR or 2.5Y, values 5 or 6, and chroma 3 through 6. Mottles are in shades of gray and brown. Textures are clay loam, sandy clay loam, or loam.
The Btcg and underlying Btvg horizons are distinctly mottled in shades of gray, yellow, brown, and red, or they have matrix colors of light gray and are mottled. Texture is sandy clay loam, loam, or clay loam. The amount of plinthite ranges from 5 to 30 percent. Iron concretions up to 2.5 cm in diameter make up 5 to 25 percent of all B horizons.
The Cg horizon, where present, is mottled in shades of red, brown, yellow, and gray. Texture is sandy clay loam, clay loam, or sandy clay.
COMPETING SERIES: These are the Clarendon, Irvington, and Saucier series. Clarendon and Saucier soils have less than 5 percent hard iron concretions in their textural control sections. In addition, Clarendon soils have less than 20 percent silt in the control section and lack gray mottles within 20 inches of the surface. Irvington soils are moderately well drained and have mottles with chroma 2 or less deeper than 20 inches.
GEOGRAPHIC SETTING: These soils occur on nearly level and slightly depressed Coastal Plain uplands with gradients of 0 to 2 percent. The regolith is marine deposits of medium texture. The climate is warm and humid, nearly subtropical. Near the type location, the mean annual air temperature is about 67 degrees F., and the average annual precipitation is about 67 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Irvington series and the Atmore, Bama, Benndale, Escambia, Grady, Harleston, Malbis, and Poarch series. Atmore soils are gleyed throughout and, along with Benndale, Escambia, Harleston, and Poarch soils, have less than 18 percent clay in the control section. Bama, Benndale, and Harleston soils have less than 5 percent plinthite within 60 inches of the surface. Grady soils are gleyed throughout and have control sections with more than 35 percent clay. Malbis soils are better drained and lack mottles with chromas of 2 or less in the upper 30 inches of the soil.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow permeability.
USE AND VEGETATION: Most of these soils are used for cropland. Some areas are used for pasture and woodland. Native vegetation consists of slash pine, longleaf pine, loblolly pine, sweetgum, other hardwoods with an understory dominated by gallberry and wiregrass.
DISTRIBUTION AND EXTENT: Alabama, Florida, Georgia, Mississippi, Texas, and possibly Louisiana. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Auburn, Alabama
SERIES ESTABLISHED: Baldwin County, Alabama; 1961.
REMARKS: Robertsdale soils were formerly identified as a flat phase within the Irvington series and placed in the Red-Yellow Podzolic great soil group with a fragipan. In this revision the classification is changed to Plinthaquic Paleudults. Silt content is specified as being over 20 percent.
Water table is at 15 to 30 inches in winter and spring.