Dissertations and Theses

Influence of relief curves on the physical and mineralogical attributes of a sandstone developed argisol.

Author: LĂ­via Arantes Camargo

Keywords: relief curves; soil physics; mineralogy; spatial variability

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Summary

The objective of this work was to evaluate the influence of the relief curves on the physical and mineral attributes of the clay fraction as well as to evaluate the dependence and variability of these attributes. A mesh size of 100 x 100 m was delimited in an area characterized by the convex shape and another in an area characterized by the concave form. The meshes have a regular spacing of 10 x 10 m and the crossing points of this spacing determined the collection points of the samples, in a total of 121 georeferenced sample points in each mesh. The physical attributes were evaluated at depths 0.00- 0.20 and 0.20-0.40 m and mineralogical attributes at depth 0.00-0.20 m. The physical attributes analyzed were: weighted average diameter, geometric mean diameter, aggregates larger than 2 mm, aggregates between 2 and 1 mm, aggregates smaller than 1 mm, micropores, macropores, total pore volume, soil density, resistance to penetration and The mineralogical attributes of the clay fraction were: width at half height, mean crystal diameter of iron oxides and kaolinite and gibbsite, and isomorphic substitution and specific surface area of hematite and goethite. The contents of goethite and hematite and goethite + (goethite + hematite) [Gt / (Gt + Hm)] and kaolinite / (kaolinite + gibbsite) [Ct / (Ct + Gb)] were also calculated. The data were submitted to the statistical and geostatistical analyzes to evaluate the spatial variability and influence of the curvatures in these attributes. To evaluate the relationship between the attributes of mineralogy and physicists, simple and spatial correlation analyzes were performed. The physical and mineralogical attributes and their variability were dependent on the relief curvatures. It was also observed the influence of goethite and gibbsite crystallinity on the physical quality of the soil.