LOCATION ATTOYAC TX+LAEstablished Series
TAXONOMIC CLASS: Fine-loamy, siliceous, semiactive, thermic Typic Paleudalfs
TYPICAL PEDON: Attoyac fine sandy loam, on a smooth 1 percent slope in grass. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; brown (7.5YR 5/4) fine sandy loam; weak fine subangular blocky structure; soft, very friable; many fine and few coarse roots; common fine and medium pores; many medium worm casts; moderately acid; clear smooth boundary.
A--7 to 12 inches; brown (7.5YR 5/4) fine sandy loam; weak fine subangular blocky structure; soft, very friable; many fine and common medium roots; common fine and medium pores; many medium worm casts; strongly acid; clear smooth boundary. (combined A horizons are 3 to 20 inches thick)
Bt1--12 to 17 inches; red (2.5YR 4/6) fine sandy loam; with 30 percent brown (7.5YR 5/4) spots of A material; weak coarse subangular blocky structure parting to weak fine subangular blocky structure; soft, very friable; many fine and few medium roots; common medium and coarse pores; patchy clay films on faces of peds; common medium worm casts; strongly acid; clear smooth boundary. (0 to 5 inches thick)
Bt2--17 to 27 inches; red (2.5YR 4/6) sandy clay loam; weak medium prismatic structure parting to moderate fine subangular blocky structure; slightly hard, very friable; many fine and few medium roots; many fine and medium pores; continuous red (2.5YR 4/8) clay films on faces of peds; very thin skeletans on surface of some prisms; few iron-manganese concretions; few fine worm casts; strongly acid; gradual smooth boundary. (5 to 20 inches thick)
Bt3--27 to 51 inches; red (10R 4/6) sandy clay loam; moderate coarse prismatic structure parting to moderate fine subangular blocky structure; slightly hard, very friable; many fine and few medium roots; common fine and medium pores; continuous dark red (10R 3/6) clay films on faces of peds; very thin skeletans on surface of some prisms; few iron-manganese concretions; very strongly acid; gradual smooth boundary. (8 to 30 inches thick)
Bt4--51 to 72 inches; red (2.5YR 4/8) sandy clay loam; moderate coarse prismatic structure parting to moderate fine subangular blocky structure; slightly hard, very friable; many fine and few medium roots; common fine pores; continuous dark red (2.5YR 3/6) clay films on faces of peds; very thin skeletans on surface of some prisms; few iron-manganese concretions; very strongly acid; gradual smooth boundary. (8 to 30 inches thick)
Bt5--72 to 80 inches; red (2.5YR 4/8) fine sandy loam; few medium distinct strong brown (7.5YR 5/8) redox concentrations; moderate coarse prismatic structure parting to moderate fine subangular blocky structure; soft, very friable; common fine and few medium roots; common fine pores; discontinuous yellowish red (5YR 5/8) clay films on faces of peds; very thin skeletans on surface of some prisms; about 10 percent discontinuous reddish yellow (7.5YR 7/6) sand and silt coatings between peds; strongly acid;
TYPE LOCATION: Nacogdoches County, Texas; from intersection South Loop 204 and U.S.Highway in Nacogdoches, 8 miles south on U.S. 59; 2 miles west on county road to Stephen F. Austin Experiment Forest Hdq; 1620 feet northeast into Plant Materials Center grass plot.
RANGE IN CHARACTERISTICS: Solum thickness is more than 80 inches. Depth to the argillic horizon ranges from 3 to 20 inches. Rounded quartzite and ironstone pebbles range from 0 to 5 percent by volume throughout. The weighted average clay content of the control section ranges from 18 to 25 percent and the silt content ranges from 20 to 30 percent. Base saturation at 50 inches below the top of the Bt horizon ranges from 35 to 60 percent.
The A horizon has colors in shades of brown or red with hue of 2.5YR to 10YR, value of 4 or 5, and chroma of 2 to 8. Some pedons have dark surface layers with value of 3, but these layers are less than 7 inches thick. Texture is fine sandy loam or loam. The reaction ranges from very strongly acid to slightly acid unless limed. Some pedons have a red or dark red BA horizon.
The E horizon, where present hue of 5YR to 10YR, value of 5 or 7, and chroma of 3. Texture is fine sandy loam or loam. The reaction ranges from very strongly acid to slightly acid unless limed.
The Bw horizon, where present hue of 5YR to 10YR, value of 5 or 6, and chroma of 4. Texture is fine sandy loam or loam. The reaction ranges from very strongly acid to slightly acid unless limed.
The upper part of the Bt horizon has colors in shades of red with hue of 10R to 5YR, value of 3 to 5, and chroma of 6 or 8. The texture is fine sandy loam, loam or sandy clay loam. Reaction ranges from very strongly acid to moderately acid.
The lower part of the Bt horizon has colors in shades of red or brown with hue of 2.5YR to 7.5YR, value of 3 to 5, and chroma of 6 or 8. The texture is fine sandy loam, loam, or sandy clay loam. Reaction ranges from very strongly acid to moderately acid. Skeletans, streaks or pockets of albic materials range from none to less than 5 percent by volume.
COMPETING SERIES: These are the Bistineau, Caledonia, Darbonne, Elrose, Petal, and Sallisaw series in the same family, and the similar Bernaldo, Ruston, and Woden series in closely related families. Bistineau and Caledonia soils contain 35 percent or more silt in the control section. Darbonne soils have 15 to 60 percent ironstone fragments in some subhorizon and have sola 40 to 60 inches thick. Elrose soils have 35 percent clay or more in the middle or lower part of the Bt horizon. Petal soils contain more than 35 percent clay in the middle or lower part of the Bt horizon with colors in hue of 10YR. Sallisaw soils are very gravelly in the lower part of the Bt horizon. Bernaldo soils are glossic and have colors in hue of 7.5YR or 10YR in the upper part of the Bt horizon. Woden soils have coarse-loamy control sections.
GEOGRAPHIC SETTING: Attoyac soils are mainly on nearly level to gently sloping Pleistocene terraces in the Southern Coastal Plain, but some areas are on strongly sloping terraces and escarpments. Areas are about 25 to 100 feet above present streams. Slope gradients are dominantly less than 3 percent, but range up to 15 percent on escarpments. Average annual temperature ranges from 65 degrees to 68 degrees F. Frost free days range from 240 to 260 days and elevation ranges from 250 to 550 feet above sea level. The annual rainfall ranges from 40 to 46 inches and the Thornthwaite P-E index ranges from 66 to 80.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the closely related Bernaldo and Woden series, and the Besner and Bienville series. Bernaldo and Woden soils are on similar landscapes. Besner soils have coarse-loamy control sections, have a glossic horizon, and are on mounds. Bienville soils have sandy control sections and are on slightly lower terraces.
DRAINAGE AND PERMEABILITY: Attoyac soils are well drained. They have moderate permeability. Runoff is negligible on 0 to 1 percent slopes, very low on 1 to 3 percent slopes, low on 3 to 5 percent slopes, and moderate on 5 to 15 percent slopes.
USE AND VEGETATION: Used mainly for pastureland and woodland. Some areas are cropped to corn, small grains, or truck crops. Native vegetation is mixed pine and hardwood forest consisting of shortleaf and loblolly pine, southern red oak, and sweetgum. Pastures are mainly improved bermuda grasses, bahiagrass or common bermuda grass. Pastures are commonly overseeded with crimson clover, arrowleaf clovers, vetch, or singletary peas.
DISTRIBUTION AND EXTENT: Eastern Texas and possibly Louisiana. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Nacogdoches County, Texas; 1976.
REMARKS: The series was updated in 2002 to allow very strongly acid reaction in the epipedon, and to allow a thin E or Bw horizon above the argillic horizon. Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface of the soil to a depth of 12 inches (Ap and A horizons)
Argillic horizon - the zone from 12 to 80 inches (Bt1 to Bt5 horizons).
ADDITIONAL DATA: NSSL, S74TX-347-1, S88TX-347-001.