LOCATION GUANICA PREstablished Series
TAXONOMIC CLASS: Fine, smectitic, isohyperthermic Typic Calciaquerts
TYPICAL PEDON: Guanica clay--cultivated (Colors are for moist soil).
Ap--0 to 4 inches; black (5YR 2.5/1) clay; moderate fine medium granular structure; hard, firm; very sticky, very plastic; many fine and medium roots; about 1 percent, by volume, pebbles; noneffervescent; slightly alkaline; abrupt wavy boundary. (4 to 19 inches thick)
BA--4 to 12 inches; black (10YR 2/1) clay; strong coarse prismatic and strong fine and medium angular blocky structure; hard, firm; very sticky, very plastic; many fine and medium roots; common faint pressures faces; few fine and medium calcium carbonate concretions; about 1 percent, by volume, pebbles; slightly effervescent; slightly alkaline; clear wavy boundary. (7 to 11 inches thick)
Bssk1--12 to 25 inches; black (5YR 2.5/1) clay; strong coarse wedge-shaped and strong fine and medium angular blocky structure; hard, firm; very sticky, very plastic; common fine and medium roots; many faint intersecting slickensides having polished and grooved surfaces; few fine and medium calcium carbonate concretions; about 1 percent, by volume, pebbles; strongly effervescent; moderately alkaline; clear wavy boundary.
Bssk2--25 to 33 inches; 70 percent black (5YR 2.5/1) and 30 percent dark reddish brown (5YR 3/3) clay; strong coarse wedge-shaped and strong fine and medium angular blocky structure; hard, firm; very sticky, very plastic; few fine and medium roots; many faint intersecting slickensides having polished and grooved surfaces; few fine and medium calcium carbonate concretions; about 1 percent, by volume, pebbles; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bssk3--33 to 52 inches; 80 percent dark reddish brown (5YR 3/3) and 20 percent dark reddish brown (5YR 3/2) clay; strong coarse wedge-shaped and strong medium and coarse angular blocky structure; hard, firm; very sticky, very plastic; few very fine roots; many faint intersecting slickensides having polished and grooved surfaces; common faint black (5YR 2.5/1) organic coats; few very fine calcium carbonate concretions; about 1 percent, by volume, pebbles; strongly effervescent; moderately alkaline; clear wavy boundary. (Combined thickness of Bssk horizons range from 11 to 54 inches)
Bsszk1--52 to 68 inches; reddish brown (2.5YR 4/3) clay; strong coarse wedge-shaped and strong medium and coarse angular blocky structure; hard, firm; very sticky, very plastic; few very fine roots; many faint intersecting slickensides having polished and grooved surfaces; many fine gypsum crystals; few faint organic coats; few fine and medium soft masses of calcium carbonate; few very fine and fine iron-manganese concretions; about 1 percent, by volume, pebbles; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bsszk2--68 to 80 inches; reddish brown (2.5YR 4/3) clay; strong coarse wedge-shaped and strong medium and coarse angular blocky structure; hard; firm; very sticky, very plastic; few very fine roots; many faint intersecting slickensides having polished and grooved surfaces; common fine gypsum crystals; few faint iron-manganese stains; few fine and medium soft masses of calcium carbonate; few very fine and fine iron-manganese concretions; about 1 percent, by volume, pebbles; strongly effervescent; moderately alkaline. (Combined thickness of Bsszk horizons range from 11 to 43 inches)
TYPE LOCATION: Guanica, Puerto Rico. Approximately 2.3 miles southeast from the intersection of P.R. Hwy 121 and P.R. Hwy 367 near the Machuchal community; about 0.5 mile northeast from the Lajas Valley main drainage channel; about 2,300 feet southeast from dirt road in a naturalized pastureland. USGS Sabana Grande topographic quadrangle (1966); lat. 18 degrees 00 minutes 30 seconds N.; long. 66 degrees 57 minutes 19 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness is more than 60 inches. Reaction ranges from slightly alkaline to moderately alkaline throughout. Content of pebbles range from less than 5 percent, by volume, throughout the profile.
The A or Ap horizon has hue of 10YR or 2.5Y, value of 2 or 3, and chroma of 1 to 3. Soft masses of calcium carbonate range from none to common. Texture is clay.
The AB or BA horizon has hue of 10YR or 2.5Y, value of 2 or 3, and chroma of 1 or 2. Soft masses of calcium carbonate range from none to common. Pressure faces range from none to common. Texture is clay.
The Bss horizon, where present, have hue of 5YR to 2.5Y, value of 2.5 or 3, and chroma of 1 or 2. Soft masses of calcium carbonate and iron-manganese range from none to few. Texture is clay.
The Bssk horizon has hue of 5YR to 2.5Y, value of 2 to 5, and chroma of 1 to 6. Soft masses of calcium carbonate and iron-manganese masses range from common to many. Texture is clay.
The Bsszk horizon has hue 2.5YR to 10YR, value of 3 to 5, and chroma of 2 to 6. Soft masses of calcium carbonate and iron-manganese masses range from common to many. Gypsum crystals range from common to many. Texture is clay.
COMPETING SERIES: These are no known series in the same family.
GEOGRAPHIC SETTING: Guanica soils are on basin floors of the Semiarid Coastal Plains MLRA. Slopes range from 0 to 1 percent. They formed in clayey alluvial sediments weathered from igneous, metamorphic and sedimentary rocks. The climate is semiarid tropical. The average annual precipitation range from 30 to 45 inches and the average annual temperature ranges from 76 to 78 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Aguirre, Cartagena, Fe, and Fraternidad soils. Aguirre, Cartagena, and Fraternidad soils do not have salt accumulation in the subsoil. In addition, Cartagena soils have less clay in the control section and mixed mineralogy. Fraternidad soils are moderately well drained, are not saline, and have less clay in the control section. Fe soils have less clay in the control section and are moderately saline at depths of 5 to 8 inches.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; very slow permeability.
USE AND VEGETATION: Most areas of Guanica soils are used for sugarcane and native pasture. The vegetation consists of Angletongrass, Paraguita grasses, Rayo, Mesquite, halophytic plants, and other native and introduced species.
DISTRIBUTION AND EXTENT: Lajas Valley of Puerto Rico. The series is small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Soil Survey of Puerto Rico; 1936.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Surfaces features - gilgai pattern and cracks that open and close periodically.
Mollic epipedon - the zone from 0 to 12 inches (Ap and BA horizons).
Slickensides and vertic features - the zone from 12 to 79 inches (Bssk1, Bssk2, Bssk3, Bsszk1 and Bsszk2 horizons).
Calcic horizons - the zone from 12 to 79 inches (Bssk1, Bssk2, Bssk3, Bsszk1 and Bsszk2 horizons).
Salic horizons - the zone from 52 to 79 inches (Bsszk1 and Bsszk2 horizons).
The classification was updated from Very-fine, smectitic, isohyperthermic Sodic Epiaquerts to Very-fine, smectitic, isohyperthermic Typic Calciaquerts due to low electrical conductivity levels and the presence of calcic horizon in the subsoil.
ADDITIONAL DATA: Characterization pedon - Guanica Municipality, Puerto Rico; S81PR007006, S95PR-055-002, S95PR-055-002A. Sample by NSSL, Lincoln, NE., 08/1981, 06/1995.
Guanica soils are in MLRA 273.