LOCATION COROZAL PREstablished Series
TAXONOMIC CLASS: Very-fine, parasesquic, isohyperthermic Typic Hapludults
TYPICAL PEDON: Corozal clay - Pangola grass. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 7 inches; dark reddish brown (5YR 3/4) clay; moderate fine subangular blocky structure; firm, slightly sticky, slightly plastic, many fine roots; very strongly acid, clear wavy boundary. (6 to 10 inches thick)
Bt1--7 to 9 inches; mixed dark red (2.5YR 3/6) and grayish brown (10YR 5/2) clay; moderate fine subangular blocky structure; firm, slightly sticky, plastic; thick continuous clay films, many fine roots; very strongly acid; clear wavy boundary. (1 to 3 inches thick)
Bt2--9 to 13 inches; red (2.5YR 4/6) clay with reddish brown (5YR 4/4) on surfaces of peds and root channels; moderate medium prismatic breaking to moderate medium subangular blocky structure; firm, slightly sticky, plastic; thick continuous clay films, many fine roots; very strongly acid; gradual wavy boundary. (4 to 10 inches thick)
Bt3--13 to 24 inches; red (2.5YR 4/6) clay with yellowish brown (10YR 5/6) coatings on surfaces of peds and root channels; moderate medium subangular blocky structure; firm, slightly sticky, plastic; thin continuous clay films on faces of peds and root channels; common fine roots; very strongly acid; gradual wavy boundary. (8 to 15 inches thick)
Bt4--24 to 32 inches; red (2.5YR 5/6) clay with yellowish brown (10YR 5/6) on surfaces of peds and root channels; moderate medium subangular blocky breaking to weak fine subangular blocky structure; friable, slightly sticky, slightly plastic; very few patchy clay films on vertical faces of peds; few fine roots; very strongly acid; gradual wavy boundary. (7 to 14 inches thick)
Bt5--32 to 40 inches; yellowish red (5YR 5/6) clay; weak fine subangular blocky structure; friable, slightly sticky, slightly plastic; very few patchy clay films on vertical faces of peds; about 30 percent by volume of soil mass is saprolite; pseudomorphs of feldspars easily crushed to shiny faces (kaolin books); very strongly acid; gradual irregular boundary. (6 to 18 inches thick)
C--40 to 60 inches; variegated colors of the saprolite; yellowish red (5YR 5/6), light gray (5YR 7/1), and strong brown (7.5YR 5/6) clay loam; massive; friable, slightly sticky, slightly plastic; saprolite easily worked with fingers, rock structure visible, pseudomorphs of feldspars easily crushed to shiny faces (kaolin books); very strongly acid.
TYPE LOCATION: Cibuco SCD, 3 miles southwest of Corozal, Puerto Rico, at Corozal Experiment Substation farm, 60 feet west of cattle weighing pen.
RANGE IN CHARACTERISTICS: The base saturation (by sum of cations) is below 35 percent throughout the solum.
The Ap horizon has color values of 3 or 4, with chromas of 4 in hues of 5YR or 7.5YR.
The Bt horizons have values of 4 or 5, with chromas of 4 to 8 in hues of 2.5YR or 5YR. Structure ranges from strong to moderate, and clay films range from thick continuous to thin patchy. Percent by volume of saprolite in the lower Bt horizon ranges from 20 to 40. Organic matter in the upper 6 inches of the argillic is below the 1.5 percent level.
The BC horizon, where present has value of 4 or 5, chroma of 4 or 6 in hues of 5YR. This horizon lacks clay films and has 30 to 60 percent saprolite.
COMPETING SERIES: These include the Cialitos, Consumo, Daguey, Humatas, Ingenio, Jagueyes, Lares, Rio Piedras, and Vega Alta series all of which are well drained and lack low chroma mottles in the upper part of the argillic horizon. Cialitos, Daguey, Humatas, and Lares soils have more than 1.5 percent organic matter in the upper part of the argillic horizons. The Consumo soils have Bt horizons less than 10 inches thick. The Ingenio and Jagueyes soils are more weathered and have lower exchange capacities in the argillic horizon. The Vega Alta soils have more than 10 percent plinthite by volume in the upper 60 inches of the soil.
GEOGRAPHIC SETTING: The Corozal soils occur on gently to moderately sloping interfluves of strongly dissected low volcanic hills with slope gradients range from 2 to 12 percent. These low hills occupy a transitional area between limestone and volcanic geologic formations. The soil formed in moderately fine to fine textured residuum of highly weathered volcanic rocks. The climate is humid tropical. The annual rainfall ranges from 75 to 90 inches and the mean annual temperature is from 74 to 78 degrees F. The variation between mean summer and mean winter soils temperatures at 20 inches is less than 9 degrees F.
GEOGRAPHICALLY ASSOCIATED: These include the competing Consumo and Humatas series.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to medium runoff; slow permeability. A perched water table occurs during the rainy season.
USE AND VEGETATION: Previously used for pineapple, sugarcane and clean tilled subsistence crops. At present time in Pangola grass and used for pasture.
DISTRIBUTION AND EXTENT: The Corozal series was recognized and classified at the Corozal Experiment substation farm. It occurs in a narrow band in the contact between the limestone and the volcanic geologic formations in the northern part of Puerto Rico.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: San Juan Area, Puerto Rico; 1974.
REMARKS: The classification was changed with the 4/91 draft from Clayey, mixed, isohyperthermic Aquic Tropudults to Clayey, mixed, isohyperthermic Aquic Haplohumults. The previous OSED date was 2/86.
The Corozal series was formerly mapped with the Lares series in the Soil Survey of Puerto Rico. The lower subsoil colors are characteristic of a well drained soil, but the upper subsoil has characteristics of a somewhat poorly drained soil. This is due to a perched water table that persists during the rainy season.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - zone from 0 to 9 inches (Ap and Bt1 horizon)
Argillic horizon - zone from 7 to 40 inches (Bt horizons)