LOCATION GUAMA PREstablished Series
TAXONOMIC CLASS: Very-fine, ferruginous, isothermic Rhodic Haploperox
TYPICAL PEDON: Guama mucky peat--forestland (Colors are for moist soil).
Oi--0 to 4 inches; black (10YR 2/1) mucky peat, crushed and rubbed; about 70 percent fiber; weak very fine granular structure; soft, very friable; nonsticky and nonplastic; many very fine and fine roots; very strongly acid; very abrupt smooth boundary. (2 to 5 inches thick)
A--4 to 13 inches; dusky red (10R 3/4) clay; strong fine granular structure; slightly hard, friable; slightly sticky and moderately plastic; many very fine, fine, medium and coarse roots; many very fine and fine irregular pores; strongly acid; clear smooth boundary. (5 to 9 inches thick)
Bo1--13 to 30 inches; dark red (2.5YR 3/6) clay; moderate fine and medium subangular blocky structure; slightly hard, friable; slightly sticky and moderately plastic; common very fine, fine, medium and coarse roots; common very fine and fine irregular pores, few very fine tubular pores; moderately acid; clear smooth boundary.
Bo2--30 to 39 inches; dark red (2.5YR 3/6) clay; moderate fine subangular blocky structure; slightly hard, friable; slightly sticky and moderately plastic; few fine and medium roots; common very fine and fine irregular pores, few very fine tubular pores; moderately acid; abrupt wavy boundary. (Combined thickness of the Bo horizons range from 19 to 26 inches.)
BC--39 to 61 inches; dark reddish brown (2.5YR 3/4) clay; weak fine subangular blocky structure; soft, friable; slightly sticky and moderately plastic; few distinct fine and medium ferriargillans; few fine and medium roots; many very fine and fine tubular pores, few fine irregular pores; about 2 percent, by volume, iron stone nodules; neutral; very abrupt wavy boundary. (20 to 42 inches thick)
C--61 to 82 inches; 20 percent dark red (10R 3/6), 20 percent dark reddish brown (2.5YR 3/4), 20 percent yellowish red (5YR 5/8), 20 percent reddish yellow (7.5YR 6/8) and olive (5Y 4/3) clay; massive; soft, friable; slightly sticky and moderately plastic; many very fine and fine tubular pores, few fine irregular pores; neutral.
TYPE LOCATION: San German, Puerto Rico. Approximately 4.2 miles east of the Rosario community from the intersection of P.R. Hwy. 330 and P.R. Hwy. 348; about 2.1 miles northeast from the intersection of P.R. Hwy. 119 and P.R. Hwy. 348; about 0.30 mile west on El Alto del Descanso trail road cut on forestland; USGS Rosario topographic quadrangle (1964); lat. 18 degrees 09 minutes 26.2 seconds N. and long. 67 degrees 00 minutes 11.1 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness range from 45 to more than 60 inches. Reaction ranges from very strongly acid to moderately acid in the Oi and A horizons, from moderately acid to slightly acid in the Bo1 and Bo2 horizons and from slightly acid to neutral in the BC and C horizons. The combined total of iron stone fragments in the control section is less than 15 percent, by volume.
The Oi horizon has hue of 7.5YR or 10YR, value of 2 or 2.5, and chroma of 1 or 2. Texture is mucky peat or muck in the fine-earth fraction.
The A horizon has hue of 10R or 2.5YR, value of 3, and chroma of 3 or 4. Texture is clay in the fine-earth fraction.
The Bo horizon has hue of 10R or 2.5YR, value of 3 or 4, and chroma of 3 to 6. Texture is clay in the fine-earth fraction.
The BC horizon has hue of 2.5YR or 5YR, value of 3 or 4, and chroma of 4 or 6. Texture is silty clay loam, clay loam or clay in the fine-earth fraction.
The C horizon has no dominant color and is multicolored in shades of red, brown and yellow. Texture is silty clay loam, clay loam or clay in the fine-earth fraction.
COMPETING SERIES: There are no known series in the same family.
GEOGRAPHIC SETTING: Guama soils are on side slopes of mountains in the Humid Mountains and Valleys MLRA. Slopes range from 20 to 60 percent. They formed in iron-rich residuum weathered from serpentinite bedrock. The climate is humid tropical. The average annual precipitation ranges from 68 to 134 inches and the average annual temperature ranges from 62 to 68 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aljibe (T), Cerro Gordo (T), El Descanso (T), Hoconuco (T) and Indiera (T) series. El Descanso (T) and Hoconuco (T) soils do not have an oxic horizon and are coarser textured. Cerro Gordo (T) soils are on more stable positions and are very deep. Aljibe (T) soils are on similar positions but are shallow to serpentinite bedrock. Indiera (T) soils are on similar positions but are deep to serpentinite bedrock.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of Guama soils are on forestland. The vegetation consists of native and introduced grasses, shrubs and trees.
DISTRIBUTION AND EXTENT: Side slopes of serpentinite mountains of the southern Humid Mountains and Valleys MLRA of Puerto Rico. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: San German Municipality, Puerto Rico; 2007. The name is from Guama ward, nearby it was originally recognized.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 13 inches (Oi and A horizons).
Oxic horizon - the zone from 13 to 39 inches (Bo1 and Bo2 horizons).
Rhodic feature - the zone from 10 to 50 inches (A, Bo1, Bo2, BC and C horizons).
This soil formed in the Jse-Serpentinite Formation (Jse).
Guama soils were formerly included in the Rosario series. A soil moisture and soil temperature study performed in the San German Area Soil Survey Update recognized the Perudic Soil Moisture Regime in Puerto Rico, recognized the isothermic soil temperature regime at 750 meters above sea level (in Perudic Soil Moisture Regime) and 900 meters above sea level (in Udic Soil Moisture Regime) and adjusted the isothermic-isohyperthermic line.
Guama soils are in MLRA 270.