LOCATION GILBERT LAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, thermic Typic Glossaqualfs
TYPICAL PEDON: Gilbert silt loam, in a slight depression adjacent to drain in soybean field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 4 inches; brown (10YR 4/3) silt loam; weak medium granular structure; friable; common fine roots; few fine brown stains on faces of peds; medium acid; abrupt smooth boundary. (3 to 7 inches thick)
Eg--4 to 12 inches; grayish brown (10YR 5/2) silt loam; few medium yellowish brown (10YR 5/6) mottles; weak medium subangular blocky structure; friable; few fine roots; few fine discontinuous vesicular pores; strongly acid; abrupt irregular boundary. (5 to 15 inches thick)
B/E--12 to 18 inches; light brownish gray (2.5Y 6/2) silty clay loam; common medium prominent strong brown (7.5YR 5/8) mottles; weak coarse prismatic structure parting to moderate medium subangular blocky; firm, hard; faint clay films on faces of peds; few fine brown concretions; tongues of grayish brown (10YR 5/2) silt loam (E) 1 to 4 cm wide extend between peds and prisms and make up about 20 percent of the horizon; very strongly acid; clear wavy boundary. (5 to 16 inches thick)
Btg--18 to 31 inches; light brownish gray (2.5Y 6/2) silty clay loam; few medium prominent yellowish brown (10YR 5/6) mottles; weak coarse prismatic structure parting to moderate medium subangular blocky; firm, hard; few faint clay films on faces of peds; common medium and fine black and brown concretions; few fine black stains on faces of peds; common faint grayish brown (10YR 5/2) silt coatings on faces of peds; very strongly acid; clear wavy boundary. (7 to 15 inches thick)
Btgn1--31 to 45 inches; grayish brown (10YR 5/2) silty clay loam; few medium distinct yellowish brown (10YR 5/6) mottles; weak coarse prismatic structure parting to moderate medium subangular blocky; firm; hard; few faint clay films on faces of peds; common fine black concretions; few fine black stains on faces of peds; few faint grayish brown silt coatings on faces of peds; common medium pockets of light gray (10YR 7/1) silt loam; strongly acid; clear wavy boundary. (5 to 15 inches thick)
Btgn2--45 to 70 inches; grayish brown (2.5Y 5/2) silty clay loam; common medium distinct yellowish brown (10YR 5/6) mottles; weak coarse prismatic structure parting to moderate medium subangular blocky; firm, hard; few faint clay films on faces of peds; few fine and medium black concretions; few medium black stains on faces of peds; strongly alkaline.
TYPE LOCATION: Franklin Parish, Louisiana; 5.5 miles south of Winnsboro; 300 feet east of parish road; 25 feet north of field road; southwest 1/4 northeast 1/4, sec. 34, T. 13 N., R. 7 E.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 60 to 100 inches. Exchangeable sodium ranges from 15 to 35 percent within 17 to 40 inches of the upper boundary of the B horizon. Reaction, except for surface layers that have been limed, ranges from medium acid to very strongly acid in the A and E horizons and the upper part of the B horizon and from neutral to strongly alkaline in the lower part of the B horizon. The effective cation exchange capacity typically ranges from 15 to 50 percent or more, saturated with exchangeable aluminum within 30 inches of the soil surface.
The Ap horizon has hue of 10YR, value of 4 to 6 and chroma of 2 or 3.
The Eg horizon has hue of 10YR or 2.5Y, value of 5 to 7, and chroma of 1 or 2. Mottles, where present, are in shades of brown or gray. Tongues of the E horizon as much as 4 inches wide extend between prisms in the upper part of the Btg horizon.
The Btg and Btgn horizons have hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 1 or 2. Texture is silt loam or silty clay loam in the upper part and loam, silt loam, silty clay loam, or clay loam in the lower part. Mottles in shades of brown or gray range from few to many.
COMPETING SERIES: Series in the same family are the Basile, Calhoun, Fountain, Frost, and Leton series. Other competing series are the Amagon, Caddo, Deerford, Foley, Guyton, Hillerman, Lafe, and Wrightsville series. Amagon, Basile, Caddo, Calhoun, Fountain, Frost, Guyton, Leton, and Wrightsville soils do not have horizons within 17 to 40 inches of the upper boundary of the B horizon that have more than 15 percent exchangeable sodium. Deerford, Foley, Hillerman, and Lafe soils have natric horizons.
GEOGRAPHIC SETTING: Gilbert soils are on level or nearly level areas and depressions on surfaces of late Pleistocene age. Slope ranges from 0 to 1 percent. The climate is warm and humid. The mean annual precipitation ranges from about 45 to 55 inches and the mean annual air temperature ranges from about 60 to 70 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Calhoun, Deerford, and Foley series and the Dexter, Egypt, Gigger, and Necessity series. Dexter, Egypt, Gigger, and Necessity soils are on higher lying convex ridges and have higher chroma in the Bt horizons.
DRAINAGE AND PERMEABILITY: Gilbert soils are poorly drained. Runoff is very slow and permeability is very slow. A perched water table is at a depth of 0 to 1.5 feet below the surface during winter and early spring.
USE AND VEGETATION: Most areas are cleared and used for cropland or pasture. The main crops are soybeans, cotton, and small grain. Woodland areas are in oaks, elm, sweetgum, honeylocust, and pine.
DISTRIBUTION AND EXTENT: Louisiana and possibly Arkansas and Oklahoma. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Franklin Parish, Louisiana, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon.................0 to 12 inches. (Ap,E)
Albic horizon......................4 to 12 inches. (E)
Argillic horizon....12 to 70 inches. (Btg,Btgn1,Btgn2)
Glossic features.................12 to 18 inches (B/E)
Accumulation of sodium...31 to 70 inches (Btgn1,Btgn2)
Aquic moisture regime