LOCATION JOBOS PREstablished Series
TAXONOMIC CLASS: Fine, kaolinitic, isohyperthermic Plinthaquic Paleudults
TYPICAL PEDON: Jobos sandy loam - native pasture.
(Colors are for moist soil.)
Ap--0 to 10 inches; dark grayish brown (10YR 4/2) moist and light brownish gray (10YR 6/2) dry, sandy loam; weak medium subangular blocky structure to single grain; loose, nonsticky, nonplastic; few fine roots; few fine subrounded black concretions; strongly acid; abrupt smooth boundary. (6 to 19 inches thick)
B21t--10 to 16 inches; red (10YR 4/6) and strong brown (7.5YR 5/6) clay; strong coarse subangular blocky structure; very hard, very firm, slightly sticky, plastic; few fine roots follow cleavage planes; thick continuous dark brown clay films on ped surfaces; strongly acid; 10 to 25 percent by volume of nonindurated plinthite; gradual smooth boundary. (5 to 8 inches thick)
B22t--16 to 29 inches; red (10R 4/6) and strong brown (7.5YR 5/6) clay with few fine distinct light gray (10YR 7/1) mottles; moderate medium and coarse subangular blocky structure; very hard, very firm, slightly sticky, plastic; few fine roots; continuous brown clay films on vertical cleavage planes and patchy clay films on horizontal planes; few fine black concretions; strongly acid; 10 to 25 percent by volume of nodules of nonindurated plinthite; gradual wavy boundary. (12 to 16 inches thick)
B23t--29 to 34 inches; red (10R 4/6), yellowish brown (10YR 5/6) and light gray (10YR 7/2) clay; weak coarse subangular blocky structure; very hard, very firm, slightly sticky, plastic; very few roots; thin patchy clay films; strongly acid; less than 10 percent by volume of nonindurated plinthite; gradual smooth boundary. (4 to 8 inches thick)
B24t--34 to 54 inches; red (10R 4/6), yellowish brown (10YR 5/6) and light gray (10YR 7/2) clay; weak coarse subangular blocky structure; very hard, very firm, slightly sticky, plastic; very thin patchy clay films on ped faces; strongly acid; less than 6 percent by volume of nonindurated plinthite.
TYPE LOCATION: Noroeste SCD, Puerto Rico; 5 miles west of the town of Isabela; 50 feet south of kilometer marker 9.1 on Highway 459.
RANGE IN CHARACTERISTICS: Thickness of the solum is over 60 inches. Thickness of the argillic horizon is over 50 inches. Content of plinthite in the B horizon varies from 6 to 30 percent. Clay films in the B horizon varies from thin patchy to thick continuous. Reaction ranges from strongly to extremely acid in the whole profile. The mean annual soil temperature is 75 degrees F.
The A horizon has hues of 10YR, values of 3 and 4, and chroma of 2 to 4. Texture is dominantly sandy loam. Structure is weak fine or medium granular or subangular blocky parting to single grain. Thickness of the A horizon is 6 to 19 inches.
The B2t horizons have red, strong brown, light gray, yellowish brown, and dark red colors in varying proportions in a reticulate pattern. Texture is clay. Structure varies from weak to strong and from medium to coarse subangular blocky. Consistence is slightly sticky or sticky and plastic.
COMPETING SERIES: There are no other known series in the same family. The Almirante, Cabo Rojo, Cidral, Espinosa, Guanajibo, Guerrero, Maleza, Sosa, Torres and Vega Alta series are similar soils in related families. The Almirante and Guanajibo soils lack the low chroma mottles. The Bejucos, Cidral, Espinosa and Maleza soils lack the nonindurated plinthite within 60 inches from the surface. The Cabo Rojo and Vega Alta soils have mixed mineralogy in the clay fraction. The Guerrero soils have thicker sandy surface layers. The Sosa soils have ustic moisture regimes. The Torres soils have higher organic matter content in the upper argillic horizons.
GEOGRAPHIC SETTING: The Jobos soils are gently sloping and sloping soils in the coastal plains on slope gradients of 2 to 12 percent. The texture is clay sediments overlain by sandy sediments. The climate is humid tropical. The average annual precipitation ranges from 67 to 70 inches and the mean annual temperature is 77 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Bejucos, Guerrero, Maleza, and Rio Lajas series. The Algarrobo, Arecibo, and Corozo soils have illuvial accumulation of organic matter. The Algarrobo, Arecibo, Corrizales, Corozo soils are sandy throughout.
DRAINAGE AND PERMEABILITY: Moderately well drained, runoff is slow and permeability is rapid in the A horizons and slow in the B2t horizons.
USE AND VEGETATION: Coconuts, food crops and pasture.
DISTRIBUTION AND EXTENT: Humid coastal plains of northern Puerto Rico. The series is of moderate extent with about 6,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: Noroeste SCD, Puerto Rico; 1972.