Pedogênese em uma sequência latossolo-podzólico na borda de um platô na depressão periférica paulista
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Data
1999
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Resumo
A soil sequence (Oxisol ® Ultisol ® Alfisol) was studied on the border of a plateau,
which is the oldest regional surface near the Piracicaba river valley (southeastern Brazil).
Seven pits were identified, sampled and morphologically described under the different
segments of the sequence (end of summit, shoulder, backslope and footslope). A bi-dimensional
sketch of the soil horizons was drawn. Undeformed soil samples were taken for
micromorphological studies, and mineralogical, chemical and granulometric analyses were
performed. The very clayey Oxisols of the flat summit are developed on a neo-cenozoic cover
and the Ultisols resulted from a lateral pedologic Latosol transformation gradually receiving
at the end of the backslope a contribution from fresh siltites (Tatuí formation, Permian). The
genesis of the top Oxisol microaggregates is complex, but two processes became evident: the
geochemical microstructure ant the zoogenetics. The Bw ® Bt transition was attributed to
the subsurface densification of the microaggregates due to the levelling and convexity of the
original surface and to the lateral water flow's growing influence downstream. Further
mechanisms of argilluviation and clay destruction of the Bt horizon top by temporary
hydromorphism will complete the transformation of Bw into Bt and of the latter into E,
respectively.
Descrição
Palavras-chave
Microaggregates, Microagregados, Natural aggregate densification, Soil micromorphology, Argillic horizon degradation, Soil geomorphology, Adensamento de agregados, Micromorfologia, Degradação do horizonte Bt, Relações solo-paisagem
Citação
VIDAlL TORRADO, P.; LEPSCH, I. F.; CASTRO, S. S.; COOPER, M. Pedogênese em uma sequência latossolo-podzólico na borda de um platô na depressão periférica paulista. Revista Brasileira de Ciência do Solo, Viçosa, v. 23, n. 4, p. 909-922, 1999.