Properties of Five Tropepts in a Toposequence of the Humid Tropics in Costa Rica 1

Five Tropepts, in a toposequence developed under a warm humid climate, without a well-defined dry season, were studied. The parent material varied from limestone in the pediment and upland soils to alluvium and colluvium derived from limestone and andesite in the terrace soils. Some andesitic volcanic ash contamination may have occurred from an adjacent volcano. The objective of this work was to characterize some of the physical and chemical properties, and to relate them to soil genesis, morphology, and performance in the greenhouse using tomato (Lycopersicon esculentum Mill.) as indicator plant. The occurrence of Tropepts and particularly Eutropepts under such climatic conditions was explained by the continuous rejuvenation of the soil parent material through alluviation, colluviation, landslides, and other forms of erosion. The calcareous parent material and possibly some contamination with volcanic ash may also have been a factor. These Tropepts had moderately thin sola, increasing in thickness at higher elevation in the toposequence. They have ochric epipedons and cambic horizons. Weathering, leaching, and profile development became stronger up-slope where rejuvenation was not too drastic, as in the soils on the pediment backslope. Variations among profiles in this sequence were accounted for by changes in topography and parent material.