LOCATION DELFINA                 TX

Established Series
HCD-DWW-CLG-CLN
02/2018

DELFINA SERIES

The Delfina series consists of very deep, moderately well drained, moderate or moderately slowly permeable soils. These nearly level to gently sloping soils formed in sandy and loamy eolian deposits over calcareous loamy alluvium of Quaternary age on the Sandsheet Prairie of the South Texas Coastal Plain. Slope ranges from 0 to 5 percent. Mean annual air temperature is about 22 degree C (72 degree F) and mean annual precipitation is about 711 mm (28 in).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Typic Paleustalfs

TYPICAL PEDON: Delfina fine sandy loam--on a south facing, convex, 1 percent slope in cropland at an elevation of 50 m (165 ft). (Colors are for dry soil unless otherwise noted.)

Ap--0 to 25 cm (0 to 10 in); brown (7.5YR 5/2) fine sandy loam, brown (7.5YR 4/2) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, friable; common fine roots; common fine tubular pores; slightly acid, pH 6.5; clear smooth boundary.

A--25 to 41 cm (10 to 16 in); brown (7.5YR 5/4) fine sandy loam, brown (7.5YR 4/4) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, friable; common fine and medium roots; common fine and medium tubular pores; slightly acid, pH 6.3; abrupt smooth boundary. (combined thickness of the A horizons is 23 to 46 cm [9 to 18 in])

2Bt1--41 to 53 cm (16 to 21 in); brown (7.5YR 4/4) sandy clay loam, dark brown (7.5YR 3/4) moist; moderate coarse prismatic structure parting to moderate medium angular blocky; extremely hard, firm; common fine roots; common fine and medium tubular pores; 20 percent distinct brown (7.5YR 4/2) clay films on faces of peds; 1 percent fine faint reddish brown (5YR 5/4) masses of oxidized iron with sharp boundaries in matrix; neutral, pH 6.7; clear smooth boundary.

2Bt2--53 to 86 cm (21 to 34 in); brown (7.5YR 5/2) sandy clay loam, brown (7.5YR 4/2) moist; strong coarse prismatic structure parting to moderate medium subangular blocky; extremely hard, firm; few fine roots; few fine tubular pores; 22 percent distinct brown (7.5YR 4/2) clay films on faces of peds; 1 percent fine faint reddish brown (5YR 5/4) masses of oxidized iron with sharp boundaries in matrix; 1 percent fine masses of calcium carbonate; slightly alkaline, pH 7.6; gradual smooth boundary. (combined thickness of the 2Bt horizons is 30 to 100 cm [12 to 40 in])

2Btk1--86 to 127 cm (34 to 50 in); brown (7.5YR 5/4) sandy clay loam, brown (7.5YR 4/4) moist; strong coarse prismatic structure parting to moderate medium subangular blocky; very hard, firm; common fine roots; common fine tubular pores; 15 percent distinct brown (7.5YR 4/2) clay films on faces of peds; 11 percent medium faint reddish brown (5YR 5/4) masses of oxidized iron with sharp boundaries in matrix; 11 percent medium prominent light olive brown (2.5Y 5/6) masses of iron depletions with sharp boundaries in matrix; 11 percent fine masses of calcium carbonate; slightly effervescent; strongly alkaline, pH 8.5; clear wavy boundary.

2Btk2--127 to 165 cm (50 to 65 in); pink (7.5YR 7/4) sandy clay loam, light brown (7.5YR 6/4) moist; strong coarse prismatic structure parting to moderate medium subangular blocky; hard, friable; few fine roots; common fine tubular pores; 8 percent distinct brown (7.5YR 4/2) clay films on faces of peds; 1 percent fine distinct reddish brown (5YR 5/4) masses of oxidized iron with sharp boundaries in matrix; 11 percent coarse prominent light olive brown (2.5Y 5/6) masses of iron depletions with sharp boundaries in matrix; 11 percent fine masses of calcium carbonate; slightly effervescent; moderately alkaline, pH 8.4; gradual smooth boundary. (combined thickness of the 2Btk horizons is 31 to 112 cm [12 to 44 in])

2Btk3--165 to 203 cm (65 to 80 in); reddish yellow (7.5YR 7/6) sandy clay loam, light brown (7.5YR 6/4) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, friable; few fine roots; common fine tubular pores; 3 percent distinct brown (7.5YR 4/2) clay films on faces of peds; 1 percent fine distinct reddish brown (5YR 5/4) masses of oxidized iron with sharp boundaries in matrix; 1 percent fine prominent light olive brown (2.5Y 5/6) masses of iron depletions with sharp boundaries in matrix; 1 percent fine masses of calcium carbonate; slightly effervescent; strongly alkaline, pH 8.6.

TYPE LOCATION: Jim Wells County, Texas; from the intersection of U.S. Highway 281 and U.S. Highway 44 in Alice; 8.7 miles south on U.S. Highway 281; 3.8 miles east on FM 2508; 250 feet south in cropland.
USGS topographic quadrangle: Alice South, TX;
Latitude: 27 degrees 38 minutes 40.00 seconds N;
Longitude: 98 degrees 1 minute 30.00 seconds W.
Dutam: NAD 83

RANGE IN CHARACTERISTICS:
Soil Moisture: A Typic-ustic soil moisture regime. The soil moisture control section is dry in some or all parts for more than 90 but less than 180 cumulative days in normal years.
Mean annual soil temperature: 22.2 to 23.4 degrees C (72 to 74 degrees F)
Depth to secondary carbonates: 76 to 127 cm (30 to 50 in)

Particle-size control section (weighted average):
Clay content: 25 to 35 percent

A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5
Chroma: 2 to 4
Texture: loamy fine sand or fine sandy loam
Electrical Conductivity (dS/m): 0 to 2
Sodium Adsorption Ratio: 0 to 4
Reaction (pH): slightly acid to neutral (6.1 to 7.3)

2Bt horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 4 to 6
Chroma: 2 to 6
Texture: sandy clay loam or clay loam
Clay content: 25 to 35 percent
Coarse fragments: 0 to 3% rounded, fine or medium, quartz gravel
Clay films: 7 to 25 percent, faint or distinct, on surface of peds
Redox concentrations: few to common, fine or medium, faint or distinct, with sharp boundaries
Electrical Conductivity (dS/m): 0 to 5
Sodium Adsorption Ratio: 0 to 8
Calcium carbonate equivalent: 0 to 5 percent.
Effervescence: none to slight
Reaction (pH): slightly acid to moderately alkaline (6.1 to 8.4)

2Btk horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 5 to 7
Chroma: 3 to 6
Texture: fine sandy loam or sandy clay loam
Clay content: 15 to 35 percent
Coarse fragments: 0 to 5% rounded, quartz gravel
Clay films: faint or distinct on surface of peds
Redox concentrations: few to common, fine or medium, faint or distinct, with sharp boundaries
Redox depletions: none to few, fine to medium, faint to distinct, with sharp boundaries
Calcium carbonate equivalent: 5 to 15 percent.
Identifiable secondary carbonate: few to common (to about 5 percent), fine to medium, in matrix
Electrical Conductivity (dS/m): 0 to 5
Sodium Adsorption Ratio: 0 to 8
Effervescence: slight to strong
Reaction (pH): slightly alkaline to strongly alkaline (7.4 to 9.0)

COMPETING SERIES: There are no other series in this family. Similar soils are the Leming, Miguel, Nueces, Papalote, Premont, Raisin, and Suerte(T) series.
Premont and Raisin soils: have a clay decrease of more than 20 percent of the maximum within 150 cm (60 in)
Leming, Miguel, and Papalote soils: have more than 35 percent clay in the particle-size control section.
Nueces soils: have a sandy surface more than 51 cm (20 in) thick.
Suerte soils: have an ustic moisture regime bordering on aridic.

GEOGRAPHIC SETTING:
Parent material: sandy and loamy eolian sediments over calcareous loamy alluvium of Quaternary age
Landscape: coastal plains
Landform: paleoterrace or vegetated sand sheets
Slope: 0 to 5 percent
Precipitation pattern: June through August and December through February are the driest months. These soils are intermittently moist in September through November and March through May.
Mean annual precipitation: 508 to 762 mm (20 to 30 in)
Thornthwaite P-E Index: 31 to 44
Mean annual temperature: 21.7 to 23.4 degrees C (71 to 74 degrees F)
Frost-free period: 285 to 330 days
Elevation: 9.1 to 228.6 m (30 to 750 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Clareville, Colmena, Czar, Nueces, Premont, and Sarita series.
Clareville and Czar soils: are on concave toeslope positions on stream terraces and have a mollic epipedon thicker than 51 cm (20 in).
Nueces and Sarita soils: are on similar surfaces but have sandy surfaces thicker than 51 cm (20 in).
Premont soils: are on similar positions, do not have redox concentrations in any horizons, and have a clay decrease of more than 20 percent of the maximum within 152 cm (60 in).

DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is moderate or moderately slow. Runoff is medium on slopes less than 1 percent and high on 1 to 5 percent slopes.

USE AND VEGETATION: Major uses include livestock grazing, forage production, wildlife habitat and crop production. Citrus, cotton, grain sorghum, and a wide variety of cool season vegetables are crops grown. A small acreage is used for watermelons and peanuts. Native vegetation consists of trichloris, Arizona cottontop, pink pappusgrass, and crinkleawn. Woody vegetation includes mesquite, granjeno, catclaw, tasajillo, and prickly pear.

DISTRIBUTION AND EXTENT: Sandsheet Prairie (MLRA 83E in LRR I) and Lower Rio Grande Plain (MLRA 83D in LRR I) of southern Texas. The soil is of large extent.

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

SERIES ESTABLISHED: Jim Hogg County, Texas; 1970

REMARKS: The Delfina series was originally established in Hidalgo County in 1925 and was suspended in 1963. The series was reestablished in Jim Hogg County in 1970.
The Delfina series was reclassified in 2007 from Aquic Paleustalfs to Typic Paleustalfs based on the 1989 to 2002 water table study* conducted on similar upland soils in the central part of the Texas Gulf Coast Prairie MLRA. This soil does not have aquic conditions in most years. In some years, reduced conditions develop just above and in the upper part of the argillic horizon for brief periods following extreme above-normal precipitation events. Redoximorphic features that result from these above-normal events are not diagnostic for classification.
This series has been mapped across several MLRA areas and needs further study.
*partial data in Proceedings of eighth international soil correlation meeting (VIII ISCOM) 1992, USDA-SCS National Soil Survey Center, Lincoln, NE

Edited 11/2016 (RFG-GWH): Updated competing series, geographic setting, and associated soils sections.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 41 cm (0 to 16 in)
Argillic horizon - 41 to 203 cm (16 to 80 in)
Lithologic discontinuity - 41 to 203 cm (16 to 80 in)

ADDITIONAL DATA: NSSL data from Jim Wells County (S78TX-249-001) and from Willacy County (S78TX-489-001).

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014

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National Cooperative Soil Survey
U.S.A.