LOCATION DELFINA            TX

DELFINA SERIES

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; 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; neutral; 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; 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; moderately alkaline; gradual smooth boundary. (combined thickness of the 2Bt horizons is 30 to 100 cm [12 to 50 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 distinct 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; moderately alkaline; 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; strongly alkaline; 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; moderately alkaline.

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. Alice South, TX USGS quad; Latitude: 27 degrees 38 minutes 40.00 seconds N; Longitude: 98 degrees 1 minute 30.00 seconds W. NAD 83

RANGE IN CHARACTERISTICS:
Soil Moisture: An 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. 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 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
EC (dS/m): 0 to 2
SAR: 0 to 4
Reaction: slightly acid to neutral

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
Clay films: amount- 7 to 25 percent location- on surface of peds, contrast- faint or distinct
Redox concentrations: amount-few to common, size-fine or medium, contrast- faint or distinct, boundary- sharp
EC (dS/m): 0 to 5
SAR: 0 to 8
Reaction: slightly acid to slightly alkaline

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: 25 to 35 percent
Clay films: location- on surface of peds, contrast- faint or distinct
Redox concentrations: amount-few to common, size-fine or medium, contrast- faint or distinct, boundary- sharp
Redox depletions: amount- none to few, size- fine to medium, contrast, faint to distinct, boundary- sharp
Calcium carbonate equivalent: 5 to 12 percent.
Identifiable secondary carbonate: amount- few to common, size- fine to medium, location- in matrix to about 5 percent
EC (dS/m): 0 to 5
SAR: 0 to 8
Effervescence: slightly to strongly
Reaction: slightly alkaline to strongly alkaline

COMPETING SERIES: There are no other series in this family. Similar soils are Premont, Raisin (T), Leming, Miguel, Nueces, and Papalote 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.

GEOGRAPHIC SETTING:
Parent material: sandy and loamy sediments over calcareous loamy alluvium of Quaternary age
Landform: crest on paleoterrace
Slope: 0 to 5 percent
Mean annual temperature: 22.2 to 23.4 degrees C (72 to 74 degrees F)
Mean annual precipitation: 508 to 762 mm (20 to 30 in)
Frost-free period: 22 to 24 degrees C (72 to 75 degrees F)
Elevation: 15 to 91 m (50 to 300 ft)
Thornthwaite P-E Index: 31 to 44

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 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. The ecological site is Sandy Loam, PE 31-44 (R083EY702TX) on the sandy loam surface texture, and Loamy Sand, PE 31-44 (R083EY705TX) on the loamy sand surface texture soil.

DISTRIBUTION AND EXTENT: Sandsheet Prairie (MLRA 83E in LRR I) of southern Texas. The soil is of moderate extent.

MLRA OFFICE 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
Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 38 cm (0 to 15 in)
Argillic horizon - 38 to 203 cm (15 to 80 in)
Lithologic discontinuity - 38 to 203 cm (15 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, Tenth Edition, 2006