LOCATION GUAYACAN PREstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isohyperthermic Typic Haplocalcids
TYPICAL PEDON: Guayacan clay--pastureland (Colors are for moist soil unless otherwise indicated).
Ap--0 to 8 inches; dark brown (7.5YR 3/3) clay, dark brown (10YR 3/3) dry; strong medium granular structure; firm; slightly sticky, slightly plastic; many very fine, fine, and medium roots; many very fine interstitial pores; about 2 percent, by volume, pebbles; slightly effervescent; moderately alkaline; clear wavy boundary. (4 to 15 inches thick)
Bw--8 to 12 inches; very dark grayish brown (10YR 3/2) clay, dark brown (10YR 3/3) dry; strong medium angular blocky structure; firm; slightly sticky, moderately plastic; many very fine and fine roots, few medium roots; many very fine and few fine tubular and vesicular pores; about 3 percent, by volume, pebbles; moderately effervescent; moderately alkaline; clear wavy boundary. (4 to 12 inches thick)
Bk1--12 to 25 inches; dark yellowish brown (10YR 4/4) clay, brown (10YR 4/3) dry; moderate medium subangular blocky structure; firm; slightly sticky, moderately plastic; many very fine roots, few fine roots; many very fine and few fine tubular and vesicular pores; common filaments of calcium carbonate; about 10 percent, by volume, pebbles; moderately effervescent; moderately alkaline; abrupt wavy boundary.
Bk2--25 to 45 inches; yellowish brown (10YR 5/4) gravelly loam, brown (10YR 5/3) dry; weak medium subangular blocky structure; friable; slightly sticky, slightly plastic; many very fine roots, common fine roots; many very fine and common fine tubular and vesicular pores; many prominent soft masses of calcium carbonate; about 15 percent, by volume, pebbles; strongly effervescent; moderately alkaline; clear wavy boundary. (Combined thickness of the Bk horizons ranges from 27 to 35 inches)
C--45 to 59 inches; brown (10YR 4/3) loam, brown (10YR 5/3) dry; massive; friable; slightly sticky, nonplastic; many very fine roots, common fine roots; many very fine and few fine tubular and vesicular pores; common prominent soft masses of calcium carbonate; about 5 percent, by volume, pebbles; strongly effervescent; moderately alkaline; clear wavy boundary.
2C--59 to 76 inches; very pale brown (10YR 7/3) very gravelly silt loam, very pale brown (10YR 8/2) dry; massive; friable; slightly sticky, nonplastic; few very fine roots; many very fine tubular and vesicular pores; many distinct very dark grayish brown (10YR 3/2) masses; many prominent soft masses of calcium carbonate; about 45 percent, by volume, pebbles; strongly effervescent; strongly alkaline; gradual wavy boundary.
3C--76 to 90 inches; very dark grayish brown (10YR 3/2) gravelly clay loam, very dark gray (10YR 3/1) dry; massive; friable; slightly sticky, slightly plastic; few fine and medium roots; few very fine tubular and vesicular pores; many distinct very pale brown (10YR 7/3) masses; common prominent soft masses of calcium carbonate; about 5 percent, by volume, pebbles; strongly effervescent; moderately alkaline.
TYPE LOCATION: Lajas, Puerto Rico. Approximately 2.9 miles southwest of La Parguera community, about 2.2 miles southeast of Rancho Cabassa and about 100 feet east of dirt road in pastureland. USGS Parguera topographic quadrangle (1966); lat. 17 degrees 57 minutes 58 seconds N.; long. 67 degrees 05 minutes 30 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 35 to 60 inches. Reaction is slightly alkaline or moderately alkaline in the A and Bw horizons and moderately alkaline in the Bk and C horizons.
The A or Ap horizon has hue of 7.5YR or 10YR, value of 2 or 3, and chroma of 1 to 3. Content of pebbles ranges from 0 to 10 percent, by volume. Texture is loam, clay loam, or clay.
The Bw horizon, where present, has hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 to 4. Content of pebbles range from 0 to 25 percent, by volume. Texture is loam, clay loam, clay, or their gravelly analogs.
The Bk horizon has hue of 10YR, value of 4 to 6, and chroma of 4 to 6. Filaments and soft masses of calcium carbonate range from common to many. Content of pebbles range from 5 to 25 percent, by volume. Texture is loam, clay loam, clay, or their gravelly analogs.
The C horizon has hue of 10YR to 5Y, value of 3 to 7, and chroma of 2 to 6. Content of pebbles and cobbles range from 0 to 60 percent, by volume. Texture ranges from silt loam to clay loam or their gravelly and very gravelly analogs.
COMPETING SERIES: These are no known series in the same family.
GEOGRAPHIC SETTING: Guayacan soils are on alluvial fans, ridge tops, and side slopes of the Semiarid Mountains and Valleys MLRA of southern Puerto Rico. Slopes range from 2 to 20 percent. They formed in material that weathered from limestone. The climate is tropical semiarid. 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 Duey, Esteli (T), Jacana, Parguera, and San German series. All of these soils except Parguera soils are on higher positions. In addition, Duey and San German soils are shallow to soft limestone bedrock, Esteli (T) soils are deep to soft limestone bedrock and have coarse-loamy control sections, and Jacana soils are moderately deep to saprolite of volcanic origin. Parguera soils are on similar positions and have clayey-skeletal control sections.
DRAINAGE AND PERMEABILITY: Well drained; moderately slowly permeability.
USE AND VEGETATION: Most areas of Guayacan soils are on pastureland and hayland. A few areas are in wildlife refuges. The vegetation consists mainly of Hurricane grass, raboraton, Mesquite and Holywood lignumvitae trees. Other vegetation consists of xerophytic grasses and shrubs.
DISTRIBUTION AND EXTENT: Alluvial fans, ridge tops, and side slopes of the semiarid mountains and valleys of southern Puerto Rico. The series is small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Puerto Rico; 2007. The name is from the Guayacan offshore island nearby where it was originally recognized.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 8 inches (Ap horizon).
Cambic horizon - the zone from 8 to 12 inches (Bw horizon).
Calcic horizon - the zone from 12 to 45 inches (Bk1 and Bk2 horizons).
Guayacan soils were formerly included in the Pozo Blanco series. A soil moisture study conducted in the San Germn Area Soil Survey Update recognizes the Aridic Soil Moisture Regime in southern Puerto Rico.
ADDITIONAL DATA: Characterization pedon - Lajas Municipality, Puerto Rico; S97PR-079-001. Sample by NSSL, Lincoln, NE., 06/97.
Guayacan soils are in MLRA 271.