LOCATION ALGOA TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, thermic Aeric Calciaquolls
TYPICAL PEDON: Algoa silt loam--pasture
(Colors are for moist soil unless otherwise stated.)
A--0 to 12 inches; very dark gray (10YR 3/1) silt loam, dark gray (10YR 4/1) dry; weak fine subangular blocky structure; hard, friable, nonsticky and nonplastic; common fine roots; common fine pores; few worm-casts; mildly alkaline; clear smooth boundary. (7 to 15 inches thick)
Bk1--12 to 18 inches; grayish brown (10YR 5/2) loam, light brownish gray (10YR 6/2) dry; weak coarse subangular blocky structure; hard, friable, nonsticky and nonplastic; few fine roots; 15 percent soft masses of calcium carbonate; common fine pitted concretions of calcium carbonate; 20 percent calcium carbonate equivalent; moderately alkaline; calcareous; clear smooth boundary. (4 to 20 inches thick)
Bk2--18 to 43 inches; light brownish gray (10YR 6/2) loam, light gray (10YR 7/2) dry; weak coarse subangular blocky structure; hard, friable; slightly sticky and slightly plastic; few fine roots; 30 percent soft masses of calcium carbonate; common fine pitted concretions of calcium carbonate; 33 percent calcium carbonate equivalent; few medium black concretions; moderately alkaline; calcareous gradual smooth boundary. (6 to 35 inches thick)
Bk3--43 to 58 inches; light gray (10YR 7/2) loam, white (10YR 8/2) dry; common fine distinct yellowish brown (10YR 5/8) mottles; weak coarse subangular blocky structure; hard, friable, sticky and slightly plastic; few fine roots; 35 percent soft masses of calcium carbonate; common fine pitted concretions of calcium carbonate; 45 percent calcium carbonate equivalent; moderately alkaline; calcareous; gradual smooth boundary. (0 to 20 inches thick)
2C--58 to 65 inches; gray (10YR 6/1) clay loam, light gray (10YR 7/1) dry; many fine prominent yellowish brown (10YR 5/6) mottles; massive; very hard, very firm, sticky and plastic; few medium pitted concretions of calcium carbonate; few medium black concretions; moderately alkaline.
TYPE LOCATION: Galveston County, Texas; from intersection of Farm Road 3002 and Farm Road 1266, near Dickinson, 0.3 mile north on Farm Road 1266, 200 feet east on a shell road and 50 feet north in a pasture.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to more than 60 inches. Some pedons contain a few dark concretions 2 to 4 mm in diameter. Depth to a calcic horizon ranges from 10 to 16 inches. Calcium carbonate equivalent of the 10- to 40-inch control section ranges from 15 to 40 percent but ranges up to 60 percent in some parts of the B. Soft masses of calcium carbonate range from common to many. concretions of calcium carbonate up to 3 inches across range from few to many. The silicate clay content of the control section ranges from 8 to 30 percent. Typically 20 to 50 percent of the carbonates are of clay size.
The A horizon has hue of 10YR or 2.5Y, value of 2 or 3, and chromas of 1 or 2. Texture is silt loam, loam, fine sandy loam, or silty clay loam. Reaction is slightly acid through moderately alkaline.
The Bk1 or upper B horizon has hue of 10YR or 2.5Y, value of 3 through 7, and chroma of 2. Mottles in shades of brown or yellow range from one to common. Texture is silt loam, loam, clay loam, or silty clay loam. It is typically moderately alkaline and calcareous but, in some pedons, it is a thin horizon that is mildly alkaline and noncalcareous.
The Bk2 and Bk3 horizons have hue of 10YR or 2.5Y, value of 5 to 8, and chroma of 1 to 3. Mottles in shades of yellow and brown range from one to common. Texture is loam, clay loam, or silty clay loam. The horizons are moderately alkaline and calcareous.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 to 7, and chromas of 1 to 6. Mottles in shades of yellow and brown range from none to many. Texture is clay loam, sandy clay loam, or clay. Some pedons have common coarse nodules of calcium carbonate. The reaction is neutral through moderately alkaline and noncalcareous.
COMPETING SERIES: There are no competing series in the same family. Series in similar families include Addicks, Clodine, Jeanerette, Mocarey, and Morey series. Addicks soils have argillic horizons and are in a coarse-loamy family. Clodine, Jeanerette, and Morey lack calcic horizons within 16 inches of the surface.
GEOGRAPHIC SETTING: Algoa soils are on nearly level landscapes that are moundy with or without depressional areas. Algoa soils are on the intermound or mound part of the landscape and are typically mapped as complexes with other soils. The general landscape is typically less than 1 percent, with individual areas of Algoa ranging up to 3 percent. Some short sections, along edges, the mounds range up to 10 percent over a horizontal distance of less than 30 feet. The soil formed from thick unconsolidated loamy sediments of Pleistocene age that were enriched with calcium carbonate. The climate is moist subhumid to humid. The mean annual temperature is 66 to 72 degrees F. The mean annual precipitation ranges from 40 to 60 inches and is about evenly distributed throughout the year. The Thornthwaite P-E index ranges from 62 to 80.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Mocarey and Morey soils and the Aris, Bernard, Crowley, Leton soils. Mocarey soils occur on similar landscapes. Aris, Crowley, and Morey soils occur on similar landscapes in areas that lack free carbonates. Bernard soils occur on slightly lower positions, and the Leton soils occur in depressional areas. They have argillic horizons and lack calcic horizons.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; medium surface runoff; slow internal drainage; moderately slow permeability. The soil has a perched water table at about 2 feet during the winter and that is about 5 feet during the dry part of the summer. Some areas are subject to brief flooding during high intensity rains because runoff is not removed rapidly enough.
USE AND VEGETATI0N: Used mainly for pasture and range. A few areas are used for field crops and truck crops. The native vegetation is largely a mixture of Andropogon and Paspalum species with some sedges.
DISTRIBUTI0N AND EXTENT: Gulf Coast Prairies of Southeast Texas. The series is inextensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Galveston County, Texas, 1981.
REMARKS: The soil was formerly included in the Addicks, Clodine, and Morey series. Diagnostic features recognized in this pedon are:
Mollic epipedon - 0 to 12 inches
Calcic horizon - 12 to 58 inches
Aquic moisture regime - gray colors and mottles throughout.
ADDITIONAL DATA: Field observations and texture analysis suggest the presence of an argillic horizon; however, carbonate free clay content and thin sections done in a Texas A&M University thesis called The distribution and Genesis of Calcic Horizons In Some Soils of the Texas Coast Prairie by Terrence M. Sobecki in similar soil and in a similar soil area in Galveston County failed to show any evidence for an argillic in the solum. Evidence indicates there is commonly a buried argillic horizon. This study also showed that the amount of carbonate nodules and concretions makes it a fine-loamy rather than fine-silty family.
NSSL Sample No. S81TX-167-3 suggests some evidence of moved clay in the lower solum. This is interpreted as a buried argillic horizon and the series is classified by the easily identified calcic horizon.