Characterization of the major cambisols in North Central Portugal
This study provides information about six representative
Cambisols in North Central Portugal. The study
area is part of the drainage basin of the river Vouga, where
Cambisols are most extensive. Their general characterization
includes the estimation of pH, loss-on-ignition,
organic carbon, total nitrogen, cation exchange capacity,
exchangeable cations and percent base saturation,
particle-size analysis, "free" Fe, Si and Al, mineralogy of
the clay fraction, heavy mineralogy of the fine sand
fraction and micromorphology.
These preliminary investigations revealed some
distinctive features in these soils on which particular
attention was focussed, namely their polycyclic character,
the unique characteristics of the upper horizons and the
presence of gibbsite.
Finally, UV autofluorescence was observed in weathering
products of aluminosilicates, which were identified as
gibbsite by electron-probe microanalysis and scanning
electron microscopy and compared to standard minerals. The
potential of this technique in soil micromorphological
studies was assessed.