LOCATION ISLOTE PREstablished Series
TAXONOMIC CLASS: Fine, mixed, semiactive, isohyperthermic Typic Rhodudults
TYPICAL PEDON: Islote sandy clay loam - native pasture. (Colors are for moist soil.)
Ap--0 to 8 inches; dark brown (7.5YR 3/2) sandy clay loam; moderate fine granular structure; friable, nonsticky, slightly plastic; many fine roots; medium acid; clear smooth boundary. (6 to 10 inches thick)
Bt1--8 to 12 inches; dark brown (7.5YR 3/2) 60 percent and dark red (2.5YR 3/6) 40 percent, clay; weak medium subangular blocky structure; firm, slightly sticky, plastic; common fine roots; few faint clay films; common fine white specks; slightly acid; clear smooth boundary. (3 to 7 inches thick)
Bt2--12 to 18 inches; dark red (2.5YR 3/6) clay; moderate medium and coarse subangular blocky structure; firm, slightly sticky, plastic; few fine roots; few faint clay films; many white specks; neutral; gradual smooth boundary. (6 to 9 inches thick)
Bt3--18 to 24 inches; dark red (2.5YR 3/6) clay; moderate coarse subangular blocky structure; firm, slightly sticky, plastic; common distinct clay films; few black stains; many white specks; neutral; clear smooth boundary. (6 to 9 inches thick)
Bt4--24 to 30 inches; dark red (2.5YR 3/6) clay; weak medium subangular blocky structure; firm, slightly sticky, plastic; few faint clay films; many white specks, common fine sand grains, neutral. (6 to 8 inches thick)
C--30 plus inches; partially cemented calcareous sandstone that can be penetrated with the spade.
TYPE LOCATION: Atlantico SCD, Puerto Rico; 6 meters west of dirt road, 33 meters south of kilometer marker 7.35 on Highway 681.
RANGE IN CHARACTERISTICS: Thickness of the solum and depth to the partially cemented calcareous sandstone varies from 27 to 43 inches. Thickness of the argillic horizon ranges from 21 to 33 inches. Clay films in the argillic horizon are thin patchy or discontinuous. The mean annual soil temperature ranges from 75 to 77 degrees F.
The A horizon has hues of 7.5YR or 5YR, values of 3 or 4, and chroma of 2 to 6. It is clay or sandy clay. Structure is weak or moderate, fine or medium subangular blocky.
The Bt horizons have hues of 2.5YR to 10R, values of 3 or 4, and chroma of 4 to 6. Structure is weak or moderate, medium or coarse subangular blocky. Reaction is neutral to mildly alkaline.
The C horizon is calcareous sandstone that can be penetrated with the spade. In places, it is borderline to a Cr horizon.
COMPETING SERIES: There are no other known series in the same family. The Fajardo, Juncal, San Sebastian, Rio Arriba, Rio Lajas, Tanama and Via soils are similar soils in related families. The Fajardo and Rio Arriba soils have shrink-swell behavior and lack the cemented calcareous sandstone. The Juncal soils have thicker argillic horizons and are yellower. The San Sebastain soils have coarse fragments and calcareous throughout. The Rio Lajas soils are sandy throughout. The Tanama soils are shallow to hard calcareous limestone. The Via soils are acid and coarse textured throughout.
GEOGRAPHIC SETTING: The Islote soils are gently sloping soils in terraces and low hills in the coastal plains with slope gradient of 2 to 12 percent. They are formed in fine textured materials derived from calcareous sandstone. The climate is humid tropical. The average annual precipitation ranges from 55 to 65 inches and the mean annual temperature is 78 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caracoles and San German series. The Caracoles soils are very shallow to similar calcareous sandstone. The San German soils lack argillic horizons and are very shallow to hard limestone rock.
DRAINAGE AND PERMEABILITY: Well drained, medium to slow runoff; moderate permeability.
USE AND VEGETATION: Sugarcane, food crops and pasture.
DISTRIBUTION AND EXTENT: Northern coastal plains of Puerto Rico. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: Soil Survey of Puerto Rico; 1942.
REMARKS: The classification was updated with the 4/91 draft from Clayey, mixed, isohyperthermic Typic Tropudalfs to Fine, mixed, isohyperthermic Mollic Hapludalfs. The previous OSED date was 11/75.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon with mollic feature - zone from 0 to 8 inches (Ap horizon)
Argillic horizon - zone from 8 to 30 inches (Bt horizons)
Calcareous sandstone feature - zone from 30 plus inches (C horizon)