Resumo

OBALLOS, Jajaira  e  OCHOA, Guido. Characterization of ultisols in the capaz river basin, Merida-Venezuela. Agronomía Trop. [online]. 2008, vol.58, n.4, pp.369-382. ISSN 0002-192X.

Fourteen mudstone-formed Ultisols located in Capaz River basin (Mérida, Venezuela) were characterized. Aspects such as fine texture, acid reaction, abundance of resistant materials, and coexistence of well-crystallized clay fraction kaolinite, degraded illite through interstratified minerals under disorder arrangement, and well-crystallized vermiculite are associated with inheritance from parent rock (cretaceous and acid mudstone having undergone various transformation cycles) and moderate alteration. Ultisols development in the region of this study is mainly related to parent material of sedimentary origin, being characterized by fine texture and low deposits of unstable minerals (lutite or mudstone), independent of the bioclimatic conditions.

Palavras-chave : Humid tropical mountain soils; Ultisols; parent rock.