LOCATION AGUIRRE PREstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, isohyperthermic Sodic Haplusterts
TYPICAL PEDON: Aguirre clay--pastureland. (Colors are for moist soil.)
Ap--0 to 10 inches; very dark gray (N 3/0) clay; moderate fine granular structure; hard, very firm; very sticky, very plastic; common fine roots; slightly effervescent; moderately alkaline; gradual wavy boundary.
A--10 to 18 inches; very dark gray (N 3/0) clay; moderate fine angular blocky structure; very hard, very firm; very sticky, very plastic; few fine roots on ped faces; common pressure faces on surfaces of peds; slightly effervescent; moderately alkaline. (Combined thickness of the A horizons range from 7 to 19 inches)
Bss1--18 to 26 inches; dark gray (5Y 4/1) clay, moderate medium and coarse angular blocky structure; very hard, very firm; very sticky, very plastic; few fine roots on faces of peds and slickensides faces; many large slickensides having distinct polished and grooved surfaces; about 3 percent, by volume, igneous rock fragments; few black (10YR 2/1) concretions of iron-manganese; strongly effervescent; moderately alkaline; clear irregular boundary.
Bss2--26 to 36 inches; 50 percent light olive brown (2.5Y 5/4) and 50 percent dark gray (5Y 4/1) clay; moderate medium and coarse angular blocky structure; very hard, very firm; very sticky, very plastic; common large slickensides having prominent polished and grooved surfaces; few fine black (10YR 2/1) concretions of iron-manganese; slightly effervescent; moderately alkaline; clear irregular boundary.
Bss3--36 to 45 inches; olive gray (5Y 5/2) clay; moderate medium and coarse angular blocky structure; very hard, very firm; very sticky, very plastic; common large slickensides having prominent polished and grooved surfaces; few black (10YR 2/1) concretions of iron-manganese; slightly effervescent; moderately alkaline; gradual wavy boundary.
Bss4--45 to 80 inches; light olive brown (2.5Y 5/4) clay; moderate medium and coarse angular blocky structure; very hard, very firm; very sticky, very plastic; few fine and medium slickensides having distinct polished and grooved surfaces; few black (10YR 2/1) concretions of iron-manganese; slightly effervescent; moderately alkaline. (Combined thickness of the Bss horizons range from 51 inches to more than 80 inches.)
TYPE LOCATION: Lajas Municipality, Puerto Rico. Approximately 3.5 miles southeast of the city of Lajas from the intersection of P.R. highway 116 and P.R. highway 117; about 200 feet east of dirt road in pasture. USGS San German topographic quadrangle (1966); lat. 18 degrees 00 minutes 33 seconds N.; long. 67 degrees 00 minutes 56 seconds W.; PRD 1940.
RANGE IN CHARACTERISTICS: Solum thickness is more than 60 inches. Reaction ranges from slightly alkaline to moderately alkaline in the A horizons, and moderately alkaline in the Bss horizons. The soil is calcareous throughout.
The A or Ap horizon has hue of 10YR or 2.5Y, value of 3 or 4, and chroma of 1 or 2; or it is neutral with value of 3 or 4. Texture is clay.
The upper part of the Bss horizon has hue of 10YR to 5Y, value of 4, and chroma of 1 or 2. Texture is clay.
The lower part of the Bss horizon has hue of 10YR to 5Y, value of 3 to 5, and chroma of 2 through 4; or there is no dominant matrix color and is multicolored in shades of brown and gray. Concretions and/or soft masses of iron-manganese ranges from none to common.
COMPETING SERIES: The Teresa series is in the same family. The somewhat poorly drained Teresa series is on similar to slightly higher positions.
GEOGRAPHIC SETTING: Aguirre soils are in depressions and valley floors. Slopes range from 0 to 1 percent. They formed in clayey marine sediments and materials derived from limestone and igneous rock. The climate is tropical semiarid. The average annual precipitation ranges from 30 to 40 inches and the average annual temperature ranges from 75 to 80 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cartagena, Fe, Fraternidad, and Guanica soils. The somewhat poorly drained Cartagena soils are on higher positions, have less clay in the control section, and have mixed mineralogy. The somewhat poorly drained Fe soils are on slightly higher positions and have less clay in the control section. The moderately well drained Fraternidad soils are on higher positions, have less clay in the subsoil, and do not have an exchangeable sodium percentage of 15 or more (SAR of 13 or more). The somewhat poorly drained Guanica soils are on similar to slightly higher positions and have gypsum accumulation in the subsoil.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow permeability.
USE AND VEGETATION: Most areas of Aguirre soils are used for hayland and native pasture. The native vegetation includes Pajon, Paraguita, and Malojillo along with introduced species.
DISTRIBUTION AND EXTENT: Depressions and valley floors of southern and southwest areas of Puerto Rico. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Lajas Municipality, Puerto Rico 1936.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - zone from 0 to 18 inches (Ap and A horizons).
Slickensides and vertic features - zone from 18 to 80 inches (Bss1, Bss2, Bss3, and Bss4 horizons).
Exchangeable sodium - more than 15 percent in Bss horizon.
ADDITIONAL DATA: Sampled as S95PR-079-005. Lab. Sample Nos. 4381-4388. Sample by NSSL, Lincoln, NE.; July 1995.
Aguirre soils are in MLRA 273.