Características mineralógicas, morfológicas e químicas de solos desenvolvidos sobre riolitos do planalto de Palmas - PR

Abstract

Farmers in the Palmas - PR region often refer to the soils of the region as "lean land" or "farmland", due to low soil fertility. However, considering that the region is formed by igneous rocks of the Serra Geral Formation that is generally associated with high fertility soils, the origin of the low fertility of the Planalto de Palmas soils is not yet known. In this sense, the objective of this work was to deepen in the understanding about the low fertility of the soils of the area in question. Five representative profiles of the landscape were selected, where 5 trenches were made and each trench was classified according to criteria, color variation using the Munssell chart, texture, structure, consistency, porosity and presence of roots. Samples of the source material and the soil were also collected for mineralogical analysis. The minerals that predominate in the source material of the soils of the region were Quartz and Microclinic that show an environment formed on lava flow with high levels of silica. In the analyzed soils, yellowish colors may be related to the absence of ferromagnesian minerals in the original rock. The high organic matter (OM) observed in the superficial horizons, evidences the strong influence of the low temperatures on the maintenance of OM in the environment. Haloisite is one of the evidences that the studied soil is little weathered, being this material is little stable and persistent unlike the kaolinite and its presence is more common in places with amena temperatures and material abundant in silica. The chemical analysis showed that the soils are acidic, very high aluminum content (Al3 +) and saturation by Al3 + (m).