LOCATION MAJAGUAS                PR

Tentative Series
ASR/AMA
04/2026

MAJAGUAS SERIES

MLRA(s)--273
Depth Class--Very deep
Drainage Class--Subaqueous drainage
Water depth range--200 to 400 centimeters
Saturated hydraulic conductivity--Moderately low to high
Parent Material--Fine-loamy estuarine deposits
Geomorphic location--Lagoon bottoms and edges of mainland coves
Slope--0 to 1 percent
Mean Annual Air Temperature--26 degrees C (79 degrees F)
Mean Annual Water Temperature--28 degrees C (82 degrees F)

TAXONOMIC CLASS: Fine-loamy, mixed, subactive, nonacid, isohyperthermic Grossic Hydrowassents

TYPICAL PEDON: Majaguas mucky loam on a lagoon bottom in a coastal lagoon, Jobos Bay. (Colors are for moist soil unless otherwise stated).

Aseg--0 to 16 centimeters; greenish black (10Y 2.5/1), mucky loam; 1 percent shell fragments; structureless, massive; very fluid; moderate sulfurous odor; positive color change with 3 percent hydrogen peroxide; strong effervescence with 30 percent hydrogen peroxide; moderately alkaline (pH 8.0), moderately alkaline (pH 8.0) oxidized pH; clear boundary.

Cseg1--16 to 51 centimeters; dark greenish gray (10Y 4/1), shelly loam; 30 percent shell fragments; structureless, massive; slightly fluid; slight sulfurous odor; positive color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; moderately alkaline (pH 8.1), moderately alkaline (pH 7.9) oxidized pH; gradual boundary.

Cseg2--51 to 108 centimeters; dark greenish gray (10Y 4/1), shelly loam; 25 percent shell fragments (small percent of Halimeda calcifications); structureless, massive; moderately fluid; slight sulfurous odor; no color change with 3 percent peroxide; no effervescence with 30 percent hydrogen peroxide; moderately alkaline (pH 8.1), moderately alkaline (pH 8.1) oxidized pH; clear boundary.

2Cseg3--108 to 197 centimeters; dark greenish gray (10Y 4/1), silty clay; 10 percent Halimeda calcifications; structureless, massive; moderately fluid; moderate sulfurous odor; no color change with 3 percent hydrogen peroxide; no effervescence with 30 percent hydrogen peroxide; moderately alkaline (pH 8.2), moderately alkaline (pH 8.2) oxidized pH; clear boundary.

2Cseg4--197 to 232 centimeters; dark greenish gray (10Y 4/1), clay loam; 10 percent Halimeda calcifications; structureless, massive; moderately fluid; moderate sulfurous odor; no color change with 3 percent hydrogen peroxide; no effervescence with 30 percent hydrogen peroxide; moderately alkaline (pH 8.2), moderately alkaline (pH 8.2) oxidized pH.

TYPE LOCATION: Salinas municipality, Puerto Rico. Las Mareas Lagoon, at Jobos Bay National Estuarine Research Reserve property. Approximately 3.2 kilometers (1.98 miles) southwest from the Jobos Bay Reserve central building and approximately 0.68 kilometers (0.42 miles) west-northwest of Punta Colchones southernmost shore point.

Latitude--17.9317760
Longitude-- -66.2380170
Datum--WGS84
Coordinate Source--Manually entered from GPS

RANGE IN CHARACTERISTICS:
Depth to bedrock--Greater than 200 centimeters
Depth to lithologic discontinuity--Typically greater than 100 centimeters
Manner of Failure--Slightly fluid to very fluid throughout
Shell fragments throughout--0 to 35 percent, by volume
Reaction throughout--Moderately alkaline (pH 7.9 to 8.4)
Oxidized reaction--Moderately alkaline (pH 7.9 to 8.4)
Sulfurous odor--Slight to strong throughout, intensity decreases with depth
Electrical conductivity (1:5 soil-water) throughout--4.0 to 10.0 dS/m

Aseg horizon-
Hue--5Y, 10Y, N
Value--2.5 to 3
Chroma--1 or less
Texture--loam, fine sandy loam, sandy loam, silt loam, sandy clay loam and their shelly and mucky analogs

Cseg horizons-
Hue--10Y, 10GY, 5GY
Value--3 to 5
Chroma--1
Texture--loam, clay loam, sandy clay loam, silt loam, or silty clay loam and their shelly or parashelly analogs.

2Cseg horizons-
Color--similar to the Cseg horizon
Texture -- shelly or parashelly sandy clay loam, clay loam, or loam
Manner of failure / fluidity class-nonfluid to moderately fluid

COMPETING SERIES: There are no competing series in the same family.

GEOGRAPHIC SETTING:
Parent Material--Fine-loamy estuarine deposits
Landscape--Coastal lagoons in Semiarid coastal plain, Puerto Rico
Landform--Lagoon bottoms and edges of mainland coves
Mean Annual Air Temperature--22 to 31 degrees C. (72 to 88 degrees F.)
Mean Annual Precipitation--508 to 1,145 millimeters (20 to 45 inches)
Mean Annual Water Temperature--26 to 32 degrees C (79 to 90 degrees F)
Water salinity range--28 to 43 parts per thousand

GEOGRAPHICALLY ASSOCIATED SOILS:
These include the Colchones, Ostiones, Placeres, and Pozuelo series:
Colchones soils--have thick organic soil horizons and are estuarine tidal stream landform areas
Ostiones soils--allow coarser textured soils and are on slightly higher submerged mainland beaches within the coastal lagoon
Placeres soils--have considerable shell fragments throughout and contain hypersulfidic materials
Pozuelo soils--have much finer textures with high percentages of clay

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--Subaqueous (permanently submersed)
Saturated hydraulic conductivity--Moderately low to high
Soil moisture regime--Peraquic
Soil is continuously inundated by saline and brackish water.

USE AND VEGETATION:
Major Uses--Areas of this soil are used for commercial and recreational fishing, recreation, wildlife habitat, and coastal carbon storage is an important ecosystem service.
Native Vegetation-- Thalassia (Turtle grass) and Halofila decipiens (Paddle grass)(Lower vegetation density).

DISTRIBUTION AND EXTENT:
General area--Coastal lagoons of Southern coastal plains of Puerto Rico.
Land Resource Region--Z - Caribbean Region
MLRA--273 - Semiarid Coastal Plains
Extent--Small

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: SPECIAL PROJECTS OFFICE

SERIES ESTABLISHED: Humacao Area, Puerto Rico Eastern Part (PR689); Salinas Municipality, Puerto Rico; 2026. The name is from ponds in Mar Negro area estuary east of Las Mareas community, where it was originally recognized.

REMARKS: This subaqueous series is mapped in areas previously published as water in Puerto Rico Soil Survey publications.

Diagnostic horizons and features recognized in this pedon--
Ochric epipedon--the zone 0 to 16 centimeters (0 to 6 inches, Aseg horizon). Peraquic soil moisture regime--Positive soil water potential (permanently submerged) at the soil surface. (under 2 to 4 meters of salt water).
High n-value--slightly to very fluid throughout
Lithologic discontinuity--the zone from 108 to 232 centimeters
Oxidized pH values--the shell fragments and Halimeda materials that occur throughout this soil buffer the oxidized pH even as sulfidic materials are likely present.

Additional Data:
Typical pedon 2023PR123304
Supporting pedons: 2024PR057415, 2024PR057401
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National Cooperative Soil Survey
U.S.A.