LOCATION SEBORUCO PREstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isohyperthermic Typic Calciargids
TYPICAL PEDON: Seboruco silty clay loam--forestland (Colors are for moist soil).
A--0 to 2 inches; dark yellowish brown (10YR 3/4) silty clay loam; weak fine granular structure; friable, moderately sticky, moderately plastic; many very fine and fine roots, common medium and coarse roots; about 5 percent, by volume, pebbles; common distinct shell fragments; violently effervescent; moderately alkaline; clear smooth boundary. (2 to 5 inches thick.)
Bt1--2 to 7 inches; very dusky red (2.5YR 2.5/2) silty clay loam; moderate medium subangular blocky structure; friable, moderately sticky, moderately plastic; many very fine and fine roots, few medium and coarse roots; about 5 percent, by volume, pebbles; common distinct shell fragments; violently effervescent; moderately alkaline; clear wavy boundary.
Bt2--7 to 11 inches; dark red (2.5YR 3/6) gravelly silty clay; weak medium subangular blocky structure; firm, moderately sticky, moderately plastic; common very fine and fine roots, many medium and coarse roots; about 30 percent, by volume, pebbles; many distinct shell fragments; violently effervescent; moderately alkaline; clear wavy boundary. (Combined thickness of the Bt horizons range from 8 to 15 inches.)
Bk1--11 to 19 inches; 60 percent very pale brown (10YR 8/3) and 40 percent red (2.5YR 5/6) gravelly silt loam; weak medium subangular blocky structure; very friable, slightly sticky, slightly plastic; few very fine, fine, and medium roots; common prominent tongues 2 to 10 cm in width filled with dark red (2.5YR 3/6) Bt material; about 20 percent, by volume, pebbles; many distinct shell fragments; many prominent soft masses of calcium carbonate; violently effervescent; slightly alkaline; abrupt wavy boundary.
Bk2--19 to 26 inches; 65 percent yellowish red (5YR 5/6) and 35 percent very pale brown (10YR 8/3) gravelly silt loam; weak fine subangular blocky structure; very friable; slightly sticky, slightly plastic; few very fine and fine roots; common prominent tongues 2 to 10 cm in width filled with dark red (2.5YR 3/6) Bt material; about 25 percent, by volume, pebbles; many distinct shell fragments; many prominent soft masses of calcium carbonate; violently effervescent; slightly alkaline; abrupt wavy boundary. (Combined thickness of the Bk horizons ranges from 10 to 20 inches.)
C--26 to 31 inches; red (2.5YR 4/8) loam; massive; friable; few very fine, fine, and medium roots; about 2 percent by volume, pebbles; few fine and medium soft masses of calcium carbonate; violently effervescent; moderately alkaline; abrupt wavy boundary. (2 to 4 inches thick)
R--31+ inches; hard consolidated unweathered limestone bedrock.
TYPE LOCATION: Guanica Municipality, Puerto Rico. Guanica State forest; approximately 1.4 miles south-southeast of La Luna community, about 1,300 feet south of road junction, and about 50 feet north west of road. Guanica topographic quadrangle; lat. 17 degrees, 58 minutes, 04 seconds N.; long. 66 degrees, 52 minutes, 54 seconds W.; PRD 1940.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 40 inches. Reaction is slightly alkaline to moderately alkaline in the A horizon and moderately alkaline in the Bt, Bk, and C horizons.
The A or Ap horizon has hue of 10R or 2.5YR, value of 2.5 or 3, and chroma of 2 or 3. Content of pebbles ranges from 0 to 10 percent, by volume. Texture is silt loam or silty clay loam.
The Bt horizon has hue of 10R to 2.5YR, value of 2.5 to 4, and chroma of 3 to 6. Content of shell fragments range from few to many. Content of pebbles ranges from 5 to 30 percent, by volume. Texture is silty clay loam or silty clay in the fine-earth fraction.
The Bk horizon has hue of 2.5YR to 10YR, value of 5 or 8, and chroma of 3 to 6. Many pedons do not have a dominant matrix color and are a mixture of these colors. Tongues filled with Bt material from 2 cm to 15 cm in thickness ranges from few to many. Content of shell fragments range from few to many. Calcium carbonate masses, nodules, concretions, or filaments range from common to many. Content of pebbles ranges from 10 to 30 percent, by volume. Texture is silt loam, silty clay loam, or silty clay in the fine-earth fraction.
The C horizon has hue of 2.5YR or 5YR, value of 3 or 4, and chroma of 4 to 8. Content of shell fragments range from none to common. Calcium carbonate masses, nodules, filaments, or concretions range from few to common. Content of pebbles and cobbles composed of calcite ranges from 0 to 30 percent, by volume. Texture is loam or silt loam in the fine-earth fraction.
The R horizon is composed of hard consolidated unweathered limestone bedrock.
COMPETING SERIES: There are no known series in the same family.
GEOGRAPHIC SETTING: Seboruco soils are on side slopes and saddles of limestone hills and mountains. They formed in shallow marine sediments overlying limestone bedrock. Slopes range from 12 to 90 percent. The climate is tropical semiarid. The mean average air temperature ranges from 78 to 82 degrees F., and the mean annual precipitation ranges from 28 to 36 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Costa (T), La Covana (T), and Pitahaya (T) soils. All of these soils are on similar positions and are shallow. In addition, Costa and La Covana soils have carbonatic control sections. Pitahaya soils have clayey-skeletal control sections.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Most areas of Seboruco soils are in forestland and are used for recreation. Some areas are used for rangeland. The vegetation consists of xerophytic grasses, shrubs, and trees.
DISTRIBUTION AND EXTENT: Puerto Rico. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Guanica Municipality, Puerto Rico; 2007.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - the zone from 0 to 2 inches (A horizon).
Argillic horizon - the zone from 2 to 11 inches (Bt1 and Bt2 horizons).
Calcic horizon - the zone from 11 to 26 inches (Bk1 and Bk2 horizons).
Lithic contact - at 31 inches (R horizon).
Seboruco soils were formerly included in the Limestone Rockland miscellaneous land type. The classification was updated with the 06/2002 draft from Fine-loamy, mixed, superactive, isohyperthermic Calcidic Haplustalfs to Fine-loamy, mixed, superactive, isohyperthermic Typic Calciargids. A soil moisture study performed in the San German Area Soil Survey Update recognizes the Aridic Soil Moisture Regime in southern Puerto Rico.
Seboruco soils are in MLRA 271.