LOCATION DEXTER LA+AR TN
Established Series
Rev. JLD:JPE
02/2013
DEXTER SERIES
The Dexter series consists of very deep, well drained, moderately permeable soils that formed in thin loess and underlying loamy and sandy sediments on terraces of Late Pleistocene Age. These soils are on elongated, narrow convex ridges. Slopes range from 0 to 8 percent.
TAXONOMIC CLASS: Fine-silty, mixed, active, thermic Ultic Hapludalfs
TYPICAL PEDON: Dexter silt loam - pasture. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; brown (10YR 4/3) silt loam; weak very fine granular structure in top 2 inches, and weak coarse platy structure below; friable; many fine roots; strongly acid; abrupt smooth boundary. (4 to 10 inches thick)
Bw--6 to 10 inches; dark brown (7.5YR 4/4) silt loam; weak fine subangular blocky structure; friable; few fine pores; strongly acid; clear smooth boundary. (0 to 6 inches thick)
Bt1--10 to 17 inches; dark brown (7.5YR 4/4) silty clay loam; ped surfaces are reddish brown (5YR 4/4); moderate medium subangular blocky structure; firm; few fine pores; faint, almost continuous clay films; few patchy black stains on peds; strongly acid; gradual wavy boundary. (6 to 20 inches thick)
Bt2--17 to 25 inches; dark brown (7.5YR 4/4) clay loam; ped surfaces are reddish brown (5YR 4/4); moderate medium subangular blocky structure; firm; few fine roots; few fine pores; common thin patchy clay films; few black stains on faces of peds; very strongly acid; gradual wavy boundary. (6 to 20 inches thick)
Bt3--25 to 32 inches; reddish brown (5YR 4/4) clay loam; ped surfaces are yellowish red (5YR 4/6); moderate medium subangular blocky structure; firm; few fine roots; few fine pores; faint patchy clay films; common patchy black stains on peds; strongly acid; gradual wavy boundary. (6 to 25 inches thick)
2BC1--32 to 44 inches; reddish brown (5YR 4/4) loam; weak coarse subangular blocky structure; friable; few fine roots; few fine pores; faint patchy clay films; common patchy black stains on faces of peds; strongly acid; clear smooth boundary. (10 to 24 inches thick)
2BC2--44 to 59 inches; dark brown (7.5YR 4/4) fine sandy loam; weak coarse prismatic structure; friable; few dark brown soft masses; few pale brown (10YR 6/3) streaks inside peds; very strongly acid; clear smooth boundary. (8 to 30 inches thick)
3C--59 to 67 inches; brown (7.5YR 4/4) loamy fine sand; massive; very friable; strongly acid .
TYPE LOCATION: Richland Parish, Louisiana; 3 miles south of Alto, 240 feet east and 1,100 feet south of the northwest corner, sec. 4, T. 15 N., R. 6 E.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 32 to 60 inches. The cation exchange capacity ranges from about 15 to 50 percent, saturated with exchangeable aluminum within 30 inches of the soil surface.
The Ap or A horizon has hue of 10YR or 7.5YR, value of 4 or 5, and chroma of 3 or 4. Texture is silt loam, loam, or very fine sandy loam. Reaction ranges from strongly acid to neutral. In severely eroded pedons, the Ap horizon can have colors and textures similar to the Bw horizon or the upper part of the Bt horizon.
The Bw horizon or the BA horizon, where present, has hue of 7.5YR or 5YR, value of 4 or 5, and chroma of 4 or 6. Texture is silt loam or loam. Reaction ranges from very strongly acid to medium acid.
The Bt horizon has ped surfaces or matrix colors with hue of 5YR, value of 4 or 5, and chroma of 4 to 6 or hue of 7.5YR, value of 4 or 6, and chroma of 6. Ped interiors have colors as given for ped surfaces or they have hue of 7.5YR, value of 4 or 5, and chroma of 4. Texture of the Bt horizon is silt loam, silty clay loam, or clay loam. Total sand content in the upper 20 inches of the argillic horizon ranges from 10 to 35 percent with less than 15 percent coarser than very fine sand . Reaction of the Bt horizon ranges from very strongly acid to medium acid.
The 2BC horizon has hue of 7.5YR or 5YR, value of 4 to 6, and chroma of 4 to 6. Texture is sandy loam, fine sandy loam, loam, sandy clay loam or clay loam. Reaction ranges from very strongly acid to medium acid. Black stains are evident on peds in most pedons.
The 3C horizon is typically fine sandy loam or loamy fine sand but ranges to sandy clay loam or clay loam. Reaction is strongly acid or very strongly acid. In some pedons the 3C horizon is stratified.
COMPETING SERIES: These are the
Armour,
Barnsdall,
Dossman,
Goodwill, and
Hicks series in the same family and the
Atwood,
Dubbs,
Gallion,
Lexington,
Memphis,
Rilla,
Silerton, and
Vian series. Armour soils have silty clay loam to clay BC horizons that contain chert fragments. The Barnsdall soils are drier for longer periods of time. Dossman soils formed in loess and contain less total sand in the textural control section. The Bt horizon of Goodwill, Dubbs, and Memphis soils have ped surfaces that have hues of 10YR and 7.5YR, and in addition, Memphis soils have less than 5 percent total sand to a depth of 48 inches. Hicks soils have a Bt horizon in colors of 10YR or 7.5YR hue, and the Bt contains coarse fragments. Atwood, Lexington, and Vian soils have sola greater than 60 inches thick. Gallion and Rilla soils have base saturation greater than 60 percent at a depth of 50 inches below the top of the argillic horizon. Rilla soils have silty ped coatings in the Bt horizon, and Gallion soils are medium acid to mildly alkaline in the Bt horizon. Silerton soils have base saturation less than 35 percent at 50 inches below the top of the argillic horizon.
GEOGRAPHIC SETTING: Dexter soils are level to gently sloping and have formed in thin loess and underlying alluvium of mixed mineralogy. They occur mostly on low terraces of the Mississippi River or its tributaries. The climate is warm and humid. Average annual rainfall ranges from about 45 to 60 inches. Mean annual temperature ranges from about 60 to 70 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing
Lexington and
Memphis soils and
Alligator,
Calloway,
Calhoun,
Foley,
Grenada,
Perry and
Providence soils. Alligator and Perry soils have B horizons with more than 35 percent clay and are poorly drained. Calloway, Grenada, and Providence soils have fragipans. Calhoun soils have grayer colors and are poorly drained. Foley soils have natric horizons.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability; slow or medium runoff.
DISTRIBUTION AND EXTENT: Arkansas, Kentucky, Louisiana, Mississippi, and Tennessee. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: AUBURN, ALABAMA
SERIES ESTABLISHED: Decatur County, Tennessee; 1943.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon.......................0 to 10 inches (Ap, Bw) Argillic horizon.....................10 to 32 inches (Bt1,Bt2,Bt3) Lithologic discontinuity...................32 inches (2BC1,2BC2) Lithologic Discontinuity...................59 inches (3C)
National Cooperative Soil Survey
U.S.A.