LOCATION PONTOTOC TX

Established Series
Rev. HCD-WHD-CLG
10/2016

PONTOTOC SERIES

The Pontotoc series consists of very deep, well drained soils that formed in thick beds of red Cambrian age sandstone bedrock. These soils occur on nearly level to moderately sloping footslopes of ridges on dissected plateaus. Slope ranges from 0 to 8 percent. Mean annual precipitation is about 660 mm (26 in), and the mean annual air temperature is about 18 degrees C (66 degrees F).

TAXONOMIC CLASS: Coarse-loamy, mixed, active, thermic Rhodic Paleustalfs

TYPICAL PEDON: Pontotoc fine sandy loam--in a cultivated field.
(Colors are for dry soil unless otherwise stated.)

Ap--0 to 13 cm (0 to 5 in); dark reddish brown (2.5YR 3/4) fine sandy loam, dark reddish brown (2.5YR 3/4) moist; weak fine granular structure; slightly hard, very friable; slightly acid; abrupt smooth boundary.

A--13 to 25 cm (5 to 10 in); dark reddish brown (2.5YR 3/4) fine sandy loam, dark reddish brown (2.5YR 3/4) moist; weak fine granular and subangular blocky structure; slightly hard, very friable; few roots; common fine and medium pores; slightly acid; diffuse smooth boundary. Combined thickness of the A horizon is 15 to 51 cm (6 to 20 in)

Bt1--25 to 53 cm (10 to 21 in); dark reddish brown (2.5YR 3/4) fine sandy loam, dark reddish brown (2.5YR 3/4) moist; weak fine subangular blocky structure; slightly hard, very friable; few roots; few fine and medium pores; 5 percent clay films; slightly acid; diffuse smooth boundary. Thickness is 13 to 36 cm (5 to 14 in)

Bt2--53 to 84 cm (21 to 33 in); dark red (2.5YR 3/6) fine sandy loam, dark red (2.5YR 3/6) moist; weak fine subangular blocky structure; hard, friable; few roots; common fine and medium pores; 5 percent clay films in pores; slightly acid; diffuse smooth boundary. Combined thickness of the upper Bt horizons is 25 to 76 cm (10 to 30 in)

Bt3--84 to 170 cm (33 to 67 in); dark red (2.5YR 3/6) sandy clay loam, dark red (2.5YR 3/6) moist; weak fine subangular blocky structure; hard, friable; few fine pores; few roots; 5 percent clay films in pores; slightly acid; clear irregular boundary. Combined thickness of the lower Bt horizons is 46 to 114 cm (18 to 45 in)

Cr--170 to 195 cm (67 to 77 in); red weakly cemented sandstone bedrock.

TYPE LOCATION: Mason County, Texas; From intersection U.S. Highway 87 and Texas Highway 29 in the town of Mason, 0.8 mile north on U.S. Highway 87, 0.6 mile west and northwest on county road, 0.4 mile west on private road, 350 yards west in cultivated field.
USGS topographic quadrangle: Grit, Texas;
Latitude: 30 degrees, 45 minutes, 21.6 seconds N;
Longitude: 99 degrees, 15 minutes, 32.4 seconds W;
Datum: NAD83

RANGE IN CHARACTERISTICS:
Soil moisture: Typic ustic moisture regime
Depth to paralithic bedrock: 152 to 203 cm (60 to 80 in)

Particle-size control section (weighted average):
Clay content: 12 to 18 percent
Rock fragments: 0 to 10 percent by volume, sandstone, cobbles and gravel

A horizon
Hue: 2.5YR or 5YR
Value: 3 or 4
Chroma: 3 to 6; In pedons where moist value and chroma are 3 or less, the epipedon is not thick enough for a mollic epipedon
Texture: Loamy sand, sandy loam, fine sandy loam
Clay content: 8 to 15 percent
Rock Fragments: 0 to 10 percent by volume; sandstone; cobbles and gravel
Effervescence: Noneffervescent
Reaction (pH): Slightly acid to neutral (6.1 - 7.3)

AB or BA horizon (where present)
Similar to the A horizon in color and texture; thickness ranges from 13 to 36 cm (5 to 14 in)

Upper Bt horizons
Hue: 10R or 2.5YR
Value: 3 or 4
Chroma: 4 to 6
Texture: Sandy loam, fine sandy loam
Clay content: 12 to 18 percent
Rock Fragments: 0 to 10 percent by volume; sandstone; cobbles and gravel
Effervescence: Noneffervescent
Reaction (pH): Slightly acid to neutral (6.1 - 7.3)

Lower Bt horizons
Hue: 10R or 2.5YR
Value: 3 or 4
Chroma: 4 to 6
Texture: Sandy loam, fine sandy loam, loam, sandy clay loam
Clay content: 15 to 30 percent
Rock Fragments: 0 to 15 percent by volume; sandstone; cobbles and gravel
Effervescence: Noneffervescent
Reaction (pH): Slightly acid to neutral (6.1 - 7.3)

Cr layer
Kind: sandstone bedrock of the Hickory formation
Cementation: weakly to moderately
Other features: The sandstone usually contains some glauconite. In some pedons, an interbedded R layer may be present.

COMPETING SERIES: There are no other soils in this family. Similar soils include the Cobb, Duval and Springer series.
Cobb soils: have fine-loamy particle-size control sections and have sola less than 100 cm (40 in)
Duval soils: have hue of 5YR or browner and have sandstone bedrock between 100 (40 in) and 150 cm (60 in).
Springer soils: includes hue of 5YR or browner and does not have sandstone within 200 cm (80 in).

GEOGRAPHIC SETTING:
Parent material: slope alluvium and residuum derived from sandstone bedrock of the Hickory Sandstone of Cambrian age
Landscape: dissected plateaus
Landform: footslopes of ridges
Slope: 0 to 8 percent
Precipitation Pattern: The majority of the yearly amount occurs during the fall and spring months. The winter and summer months are normally drier.
Mean annual precipitation: 635 to 787 mm (25 to 31 in)
Thornthwaite annual P-E index: 38 to 44
Mean annual air temperature: 18.3 to 19.4 degrees C (65 to 67 degrees F)
Frost-free period: 215 to 235 days
Elevation: 274.3 to 579.1 m (900 to 1,900 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hye, Nebgen, Oben, and Yates series.
Hye and Oben soils: occur on similar positions. In addition, Hye soils have fine-loamy particle-size control sections. Oben soils have sola less than 50 cm (20 in) to sandstone bedrock.
Nebgen and Yates soils: occur on higher associated ridges, and both soils are shallow to bedrock.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately rapid in the upper part and moderate in the lower part. Runoff is negligible on 0 to 1 percent slopes, very low on 1 to 5 percent slopes, and low on 5 to 8 percent slopes.

USE AND VEGETATION: Used for dry and irrigated cropland and for rangeland. Crops are mostly grain sorghum, peanuts, and vegetables. Considerable acreage is used for irrigated tame pastures. Rangeland vegetation is mostly hooded windmill grass, purple threeawn, sand dropseed, sandbur grasses, and a few live oak, post oak, mesquite, whitebrush, and tasajillo.

DISTRIBUTION AND EXTENT: Central Texas. Southwest Plateaus and Plains Range and Cotton Region, LRR-I: MLRA 82A-Texas Central Basin. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Recon. Soil Survey of South Central Texas - 1913.

REMARKS:
Edited 10/2016 (RFG-THW): Split Bt into upper Bt and lower Bt in range in characteristics. Updated competing series, geographic setting, and associated soils sections.

Diagnostic horizon and features recognized in this pedon are:
Ochric epipedon: 0 to 25 cm (0 to 10 in) (Ap and A horizons)
Argillic horizon: 25 to 170 cm (10 to 67 in) (Bt1, Bt2, and Bt3 horizons)
Paralithic contact: 170 cm (67 in) (top of Cr layer)

ADDITIONAL DATA: KSSL lab pedon No. 82P0854 with User Pedon ID 82TX299005

Taxomomic Version: Keys to Soil Taxonomy, 12th Edition, 2014.

National Cooperative Soil Survey
U.S.A.