LOCATION LA LUNA PREstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, isohyperthermic Typic Calciargids
TYPICAL PEDON: La Luna silty clay loam--cropland (Colors are for moist soil).
Ap--0 to 11 inches; very dark grayish brown (10YR 3/2) silty clay loam; moderate fine and medium granular structure; hard, friable; slightly sticky, moderately plastic; few very fine and fine roots; many very fine to medium irregular pores; about 8 percent, by volume, pebbles; noneffervescent; slightly alkaline; clear smooth boundary. (7 to 16 inches thick)
Bt--11 to 20 inches; very dark grayish brown (2.5Y 3/2) silty clay loam; strong fine and medium subangular blocky structure; hard, firm; slightly sticky, moderately plastic; few very fine and fine roots; common very fine and fine irregular pores and few very fine tubular pores; common fine very dark gray (2.5Y 3/1) clay films on faces of peds; slightly effervescent; slightly alkaline; clear smooth boundary. (7 to 20 inches thick)
Btk1--20 to 32 inches; very dark grayish brown (2.5Y 3/2) silty clay; strong fine and medium subangular blocky structure; hard, firm; slightly sticky, moderately plastic; few very fine and fine roots; common very fine and fine irregular and tubular pores; common faint very dark gray (2.5Y 3/1) clay films on faces of peds; many very fine and fine light yellowish brown (2.5Y 6/3) masses of secondary calcium carbonate; slightly effervescent; moderately alkaline; abrupt smooth boundary.
Btk2--32 to 44 inches; olive brown (2.5Y 4/3) silty clay loam; moderate fine and medium subangular blocky structure; hard, firm; slightly sticky, moderately plastic; few very fine roots; few very fine and fine irregular pores and many very fine to medium tubular pores; common faint dark grayish brown (2.5Y 4/2) clay films on faces of peds; many very fine and fine light yellowish brown (2.5Y 6/3) masses of secondary calcium carbonate; slightly effervescent; moderately alkaline; clear smooth boundary.
Btk3--44 to 58 inches; dark grayish brown (2.5Y 4/2) silty clay loam; weak very fine and fine subangular blocky structure; slightly hard, firm; slightly sticky, moderately plastic; few very fine roots; few very fine and fine irregular pores and common very fine to medium tubular pores; common faint dark grayish brown (2.5Y 4/2) clay films on faces of peds; common very fine and fine light yellowish brown (2.5Y 6/3) masses of secondary calcium carbonate; slightly effervescent; moderately alkaline; clear smooth boundary. (Combined thickness of the Btk horizons range from 15 to 39 inches.)
C--58 to 80 inches; dark grayish brown (2.5Y 4/2) silty clay loam; massive; slightly hard, friable; slightly sticky, slightly plastic; few very fine roots; common very fine and fine irregular and tubular pores; common very fine and fine brown (10YR 4/3) masses of iron accumulation; few very fine and fine light yellowish brown (2.5Y 6/3) masses of calcium carbonate; slightly effervescent; moderately alkaline.
TYPE LOCATION: Guanica, Puerto Rico. Approximately 0.4 mile north of the city of Guanica from the intersection of P.R. Hwy. 331 and P.R. Hwy. 332; about 1,000 feet west of P.R. Hwy. 332 on cash crops plantation. USGS Guanica topographic quadrangle (1966); lat. 17 degrees 58 minutes 55 seconds N; long. 66 degrees 54 minutes 38 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness range from 26 to 48 inches. Reaction is slightly alkaline in the A or Ap horizon and Bt horizon and moderately alkaline in the rest of the profile.
The A or Ap horizon has hue of 10YR or 2.5Y, value of 3, and chroma of 1 or 2. Texture is silty clay loam, clay loam or silty clay.
The Bt horizon has hue of 10YR or 2.5Y, value of 3, and chroma of 1 or 2. Texture is silty clay loam, clay loam or silty clay.
The Btk horizon has hue 10YR or 2.5Y, value of 3 or 4, and chroma of 2 or 3. Texture is silty clay loam, clay loam or silty clay.
The C horizon has hue of 10YR to 5Y, value of 3 or 4, and chroma of 1 to 6. Texture is sandy clay loam, silty clay loam or clay loam. In some areas the lower part of the underlying material is sand or loamy sand.
COMPETING SERIES: There are no known series in the same family. The closely related Seboruco (T) series is on higher positions and are moderately deep to limestone bedrock.
GEOGRAPHIC SETTING: La Luna soils occur in nearly level river floodplains on the Semiarid Coastal Plains MLRA. Slopes range from 0 to 2 percent. They formed in alluvial deposits of mixed origin. The climate is semiarid tropical. The average annual precipitation ranges from 28 to 36 inches and the average annual temperature ranges from 78 to 82 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cortada, San Anton and Vayas series. All of these soils are in the Ustic soil moisture regime. Cortada and San Anton soils are on similar landscapes. The poorly drained Vayas soils are on lower positions.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of La Luna soils are on cash crops plantations. The vegetation consists of native and introduced grasses, shrubs and scattered trees.
DISTRIBUTION AND EXTENT: Semiarid Coastal Plains of Puerto Rico. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Guanica Municipality, Puerto Rico; 2007. The name is from La Luna community nearby it was originally recognized.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 11 inches (Ap horizon).
Argillic horizon - the zone from 11 to 58 inches (Bt1, Btk1, Btk2 and Btk3 horizons).
Calcic horizon - the zone from 20 to 58 inches (Btk1, Btk2 and Btk3 horizons).
La Luna soils were formerly included in the San Anton series. A soil moisture study performed in the San German Area Soil Survey Update recognized the Aridic Soil Moisture Regime in southern Puerto Rico.
La Luna soils are in MLRA 273.