LOCATION VEGA BAJA PREstablished Series
TAXONOMIC CLASS: Fine, mixed, active, isohyperthermic Aquic Hapludalfs
TYPICAL PEDON: Vega Baja silty clay - Merker grass. (Colors are for moist soil.)
Ap--0 to 7 inches; dark brown (10YR 4/3) silty clay; weak fine granular structure; firm, slightly sticky, plastic; many fine roots; few fine black concretions; strongly acid; gradual wavy boundary. (4 to 12 inches thick)
A--7 to 12 inches; mixed dark grayish brown (10YR 4/2) and yellowish brown (10YR 5/8) silty clay; weak fine granular structure; firm, slightly sticky, plastic; many fine roots; few fine black concretions; strongly acid; abrupt wavy boundary. (4 to 12 inches thick)
Bt1--12 to 17 inches; dark grayish brown (10YR 4/2) and yellowish brown (10YR 5/8) clay; weak coarse subangular blocky structure; firm, slightly sticky, plastic; few fine roots; few fine black concretions; black coatings on ped faces and root channels; very strongly acid; abrupt wavy boundary. (4 to 10 inches thick)
Bt2--17 to 32 inches; mixed strong brown (7.5YR 5/8) and gray (5Y 6/1) clay; weak medium subangular blocky structure; firm, slightly sticky, plastic; seams between peds and root channels filled with gray clay; few fine black concretions; very strongly acid; gradual wavy boundary. (8 to 16 inches thick)
BC--32 to 50 inches; brownish yellow (10YR 6/8) and light gray (N 7/0) silty clay with pockets of yellowish brown clay loam materials; weak coarse subangular blocky structure; slightly sticky, slightly plastic; few peds and fracture planes coated with black; root channels and worm burrows filled with gray clay; strongly acid; abrupt wavy boundary. (12 to 20 inches thick)
C1--50 to 55 inches; light gray (N 7/0) clay with many fine distinct strong brown (7.5YR 5/8) mottles; massive; sticky, plastic; moderately acid; abrupt wavy boundary. (4 to 12 inches thick)
C2--55 to 60 inches; light gray (N 7/0) and strong brown (7.5YR 5/8) silty clay; massive; sticky, plastic; medium acid.
TYPE LOCATION: San Juan SCD, Puerto Rico, Rio Piedras Experiment Station 200 feet north on road to Food Technology Laboratory, and 200 feet to the east of road. (Section of farm north of Highway 1 to Caguas)
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 32 to 70 inches. Thickness of the argillic horizon varies from 24 to 46 inches. These soils are slightly sticky or sticky and plastic. Base saturation ranges from 40 to 80 percent at 50 inches below the top of the argillic horizon.
The A horizon has hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 to 8. It is clay, silty clay or silty clay loam. Reaction ranges from neutral to very strongly acid.
The Bt horizon has hue of 7.5YR, 10YR, or 5Y, value of 4 to 6, and chroma of 1 to 8. They are clay or silty clay. Consistence is slightly sticky or sticky and plastic. Reaction is neutral or very strongly acid.
The C horizons are silty clay or clay; sticky and plastic. Reaction varies from moderately acid to strongly acid.
COMPETING SERIES: There are no series in this family. The Candelero, Cayagua, Coloso, Corcega and Talante series are similar soils in related families. The Candelero soils have coarser textured profiles with less than 35 percent clay. The Cayagua soils are underlain by coarse textured saprolite of granitic rocks within 40 inches of the soil surface. The Coloso soils lack argillic horizons and have organic matter that does not decrease regularly with depth. The Corcega and Talante are coarser textured.
GEOGRAPHIC SETTING: The Vega Baja soils are nearly level soils on fine textured coastal plains and alluvial fans with slope gradients from 0 to 35 percent. They formed in coastal plains sediments overlain by alluvial sediments. The climate is humid tropical. The mean annual precipitation ranges from 76 to 80 inches, and the mean annual air temperature is 77 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Vega Alta, Sabana Seca, Coloso, Bajura and Toa series. The Vega Alta soils occur at higher elevations in the coastal plain, are well drained and have more than 5 percent plinthite in the B horizon. The Sabana Seca soils are poorly drained and have plinthite. The Coloso, Bajura, and Toa soils occur at lower geomorphic positions in the river flood plain. The Toa and Coloso soils have organic matter that does not decrease regularly with depth and the Bajura soils have horizons with COLE values of more than 0.09.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; slow permeability.
USE AND VEGETATION: Most of the acreage of this soil is used for the production of sugarcane, and tame grasses and used as pasture.
DISTRIBUTION AND EXTENT: Humid northern coastal plains of Puerto Rico. The series is of minor extent, about 2,100 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: Soil Survey of Puerto Rico; 1942.
REMARKS: This revision updates the classification to Aeric Endoaqualfs.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - zone from 0 to 12 inches (Ap and A horizon)
Argillic horizon - zone from 12 to 37 inches (Bt horizon)
ADDITIONAL DATA: Characterization data are available for the typical pedon S61-PR-9-1.
MLRA = 272
SIR = PR0059