LOCATION COSTA PREstablished Series
TAXONOMIC CLASS: Clayey, carbonatic, isohyperthermic, shallow Typic Torriorthents
TYPICAL PEDON: Costa very gravelly clay--naturalized pastureland (Colors are for moist soil unless otherwise indicated).
Ap--0 to 7 inches; dark yellowish brown (10YR 4/4) very gravelly clay, brown (10YR 5/3) dry; moderate medium granular structure; slightly hard, friable; slightly sticky, slightly plastic; many very fine, fine, and medium roots; many very fine and common fine interstitial pores; about 30 percent, by volume, pebbles; about 15 percent, by volume, cobbles, and about 2 percent, by volume, stones; moderately alkaline; strongly effervescent; clear wavy boundary. (7 to 10 inches thick)
AC--7 to 11 inches; dark yellowish brown (10YR 4/4) very gravelly clay, yellowish brown (10YR 5/4) dry; weak medium granular structure; soft, very friable; slightly sticky, slightly plastic; many very fine, fine, and medium roots; many very fine and fine tubular and vesicular pores; about 25 percent, by volume, pebbles; common hard calcium carbonate concretions; common distinct soft masses of calcium carbonate; moderately alkaline; strongly effervescent; clear wavy boundary. (0 to 6 inches thick)
C--11 to 19 inches; light yellowish brown (10YR 6/4) silty clay, pale yellow (2.5Y 8/2) dry; massive; soft, very friable; moderately sticky, moderately plastic; common fine and medium roots, few coarse roots; many very fine and fine tubular and vesicular pores; about 10 percent, by volume, pebbles; moderately alkaline; violently effervescent; clear wavy boundary. (4 to 9 inches thick)
Cr1--19 to 27 inches; light yellowish brown (10YR 6/4) soft semi-consolidated fractured limestone that has a silty clay texture, very pale brown (10YR 8/2) dry; moderate medium and thick platy rock structure; few fine roots and common medium roots in fracture planes; common continuous secondary calcite coatings on fracture planes; moderately alkaline; violently effervescent; clear wavy boundary.
Cr2--27 to 43 inches; 75 percent yellow (10YR 7/6) and 25 percent very pale brown (10YR 8/4) soft semi-consolidated fractured limestone that has a loam texture, very pale brown (10YR 8/2) dry; moderate medium and thick platy rock structure; common very fine, fine, and medium roots in fracture planes; common distinct secondary calcite coatings on fracture planes; strongly alkaline; violently effervescent; clear wavy boundary. (Combined thickness of the Cr horizons is from 5 to 20 inches.)
R--43 to 63 inches; very pale brown (10YR 8/2) soft consolidated limestone bedrock, white (10YR 8/1) dry; strong thick platy rock structure; few fine and medium roots in fracture planes; strongly alkaline; violently effervescent.
TYPE LOCATION: Lajas, Puerto Rico. Approximately 3.0 miles west of La Parguera community, about 1.8 miles southeast of Rancho Cabassa, and about 100 feet north of gravel road in a naturalized pastureland. USGS Parguera topographic quadrangle (1966); lat. 17 degrees 58 minutes 40 seconds N.; long. 67 degrees 05 minutes 35 seconds W.
RANGE IN CHARACTERISTICS: Depth to soft semi-consolidated limestone ranges from 10 to 20 inches. Depth to soft unweathered limestone bedrock ranges from 30 to 45 inches. Reaction is slightly alkaline or moderately alkaline throughout.
The A or Ap horizon has hue of 10YR, value of 2 to 5, and chroma of 2 to 4. Content of rock fragments range from 15 to 60 percent, by volume. Texture is clay loam or clay in the fine-earth fraction.
The AC horizon, where present, has hue of 10YR, value of 3 to 5, and chroma of 3 or 4. Content of rock fragments range from 15 to 35 percent, by volume. Texture is clay loam or clay in the fine-earth fraction.
The C horizon has hue of 7.5YR or 10YR, value of 5 to 8, and chroma of 2 to 8. Content of rock fragments range from 5 to 50 percent, by volume. Texture is clay loam, silty clay or clay in the fine-earth fraction.
The Cr horizon is composed of soft semi-consolidated and consolidated fractured limestone. It has hue of 7.5YR to 2.5Y, value of 5 to 8, and chroma of 1 to 8. It can be excavated with difficulty with hand tools, and is rippable by mechanized equipment.
The R layer is composed of soft unweathered limestone bedrock.
COMPETING SERIES: These are no known series in the same family.
GEOGRAPHIC SETTING: Costa soils are on ridge tops, summits, and side slopes of limestone hills of the Semiarid Mountains and Valleys MLRA of southern Puerto Rico. Slopes range from 5 to 90 percent. They formed in material that weathered from limestone bedrock. 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 Esteli (T), Guayacan (T), La Covana (T), and Pitahaya (T) series. Esteli (T), La Covana, and Pitahaya soils are on similar positions. In addition, Esteli soils are deep. Guayacan (T) soils are on similar to lower positions and are very deep.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Most areas of Costa soils are on naturalized pastureland or wildlife habitat. The vegetation consists of Buffel grass, Huracan grass. Other vegetation consists of Mesquite and other xerophytic grasses, shrubs and trees.
DISTRIBUTION AND EXTENT: Ridge tops, summits and side slopes of limestone hills 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: Lajas Municipality, Puerto Rico; 2007. The name is from the nearby Costa ward, where it was originally recognized.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 7 inches (Ap horizon).
Paralithic contact - the zone at 19 inches (Cr layer).
These soils were formerly included in the Duey series. A soil moisture study performed in the San German Area Soil Survey Update recognize the Aridic Soil Moisture Regime in southern Puerto Rico.
ADDITIONAL DATA: Characterization pedon - Lajas Municipality, Puerto Rico; S97PR-079-002. Sample by NSSL, Lincoln, NE., 06/97.
Costa soils are in MLRA 271.