Solos e gênese da cerosidade numa topossequência com baixa a alta atividade da fração argila

Abstract

The cerosidade is a morphological attribute of soils and is expressed as a waxy glow, mainly observed on the surface of the aggregates. Its genesis is related to the formation of films or films of clay and to features of stress in the face of peds. Cerosidade is a testimony to soil genesis and may indicate the past or present occurrence of dispersion and flocculation processes and the clayey nature of the soil. In this context, the objective of the present work was to characterize and understand the genesis of cerosidade in four soil profiles, with different expressions of this attribute in a toposequence in the municipality of Tracunhaem-PE. To do so, sampling was carried out based on the construction of a structural model of the pedological cover descita by Boulet (1993), as well as routine chemical and physical analyzes of the soils; X-ray diffractometry; successive extractions with DCB and OAA in TFSA samples; Scanning Electron Microscopy (SEM); and micromorphological analysis of soils. In general, the data indicated that the arrangement of the leucocratic and melanocratic bundles, associated with the location on the slope, influence the chemical and physical properties of the soils; that the process of argiluviation in the segments upstream of the slope are inactive or not very active; that the formation of clear extinction coatings and fills tend to form in hydraulically less active pores; and that the accumulation of iron oxides as coatings and fills between peds, associated with the presence of birefringent factories, are directly proportional to the expression of cerosidade.