LOCATION YUNES PREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, isohyperthermic, shallow Humic Dystrudepts
TYPICAL PEDON: Yunes silty clay loam - pasture
(Colors are for moist soil unless otherwise noted.)
A1--0 to 2 inches, dark reddish brown (5YR 3/2) silty clay loam, reddish gray (5YR 5/2) dry; moderate medium granular structure; slightly hard, friable, slightly sticky, slightly plastic; many fine roots; common fine shale fragments; strongly acid; clear smooth boundary. (1 to 4 inches thick)
B2--2 to 11 inches; dark brown (7.5YR 3/2) very shaly silty clay loam; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; many fine roots; 60 percent by volume of shale fragments; strongly acid; clear smooth boundary. (6 to 10 inches thick)
B3--11 to 16 inches; brown (7.5YR 4/4) very shaly silty clay loam; weak medium subangular blocky structure; friable, slightly sticky; slightly plastic; 80 percent by volume of shale fragments; strongly acid; clear smooth boundary. (3 to 6 inches thick)
Cr--16 inches; light red (2.5YR 6/8), strong brown (7.5YR 5/8), and pink (7.5 YR 7/4) bedded fractured shale; thickness of beds is 1 to 4 inches. This material can be dug with difficulty with a spade, when moist.
TYPE LOCATION: San Juan SCD, Puerto Rico, Rio Piedras Experiment Station 50 feet south of kilometer marker 2.3, Highway 847.
RANGE IN CHARACTERISTICS: Solum thickness and depth to bedrock ranges from 10 to 20 inches. The solum has base saturation of 10 to 30 percent. The soil is very strongly acid or strongly acid. The mean annual soil temperature ranges from 76 to 79 degrees F.
The A horizon has hues of 5YR and 7.5YR, values of 2 and 3, and chroma of 2 or 3. It is silty clay loam and fine shale fragments range from 0 to 15 percent by volume.
The B horizon has hues of 5YR and 7.5YR, values of 3 and 4, and chroma of 2 to 4. It ranges from shaly clay loam to very shaly silty clay loam with 35 to 85 percent shale fragments.
COMPETING SERIES: These are no other known series in the same family.
The Adjuntos, Amones, Caguabo, Cuchillas, Descalabrado, Diamond, Juana Diaz, Malaya, Mariana, Mayo, Pandura, Parcelas, Pellejas, Sabana, Santa Marta, and Southgate series are similar soils in related families. Adjuntas, Amones, Mayo, Pellejas, and Santa Marta soils lack a paralithic contact within 20 inches of the soil surface. Caguabo, Malaya, and Pandura soils have base saturation of more than 50 percent. Cuchillas soils have isothermic temperature regimes and high content of organic matter. Descalabrado, Diamond, Juana Diaz, Mariana ,and Southgate soils have ustic soil moisture regimes. Parcelas soils have higher COLE values and crack when dry. Sabana soils have volcanic rock within a depth of 20 inches of the soil surface.
GEOGRAPHIC SETTING: The Yunes soils are steep to very steep soils on sideslopes of strongly dissected uplands. Slopes range from 20 to 60 percent. The soil developed in very shaly residuum from shale. The climate is humid tropical. The average annual precipitation is 76 inches. The average annual temperature ranges from 77 to 80 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Rio Piedras series. Rio Piedras soils have thick sola, argillic horizons, and lack shaly subhorizons.
DRAINAGE AND PERMEABILITY: Well drained, surface runoff is medium to rapid, and permeability is moderate in the A horizon and moderately rapid in the B horizon.
USE AND VEGETATION: Native grasses and shrubs.
DISTRIBUTION AND EXTENT: Humid uplands of Puerto Rico. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: Soil Survey of Puerto Rico, l942.
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