Podzolization in restinga soils: relationships between change in drainage, accumulation and composition of organic matter in Espodossolos on Ilha Comprida - SP

Abstract

The most frequent soils in the coastal plain of the coast of São Paulo state are Spodosols, characterized by intense podzolization and the consequent presence of spodic horizon (Bh or Bhm). The podzolization process is characterized by the transport of organic matter (OM) in solution from the surface horizons to deeper soil, with or without iron and aluminum. Drainage can influence this process and is mainly related to the transport and accumulation of OM through the soil. On the southern coast of São Paulo state, Ilha Comprida is an example of a barrier island which, with its 74 km length and width ranging from 625 m to 5.37 km, has the remaining parts of the Pleistocene and Holocene sedimentation, vegetated by Restinga Forest. Spodosols occurence represents the differences types already described for the coastal plain of São Paulo. On the south side of Ilha Comprida is an rut exposed by erosion, in which is possible to view the large lateral variation of morphological Spodosols presents. This variation can be easily identified since the portion facing the Sea of Cananéia, where most of Spodosols remaining from Pleistocene with Bhm giants horizons, until the portion facing the ocean, where Spodosols have more incipient features of evolution, beyond Typical dune ridges. Due to the large variety of morphological features, representativeness and the easy access to Spodosols, allowing monitoration in detail of the lateral variation, this area was chosen for this study to elucidate some mechanisms related to the formation of these soils in coastal environments. The formation of Spodosols, especially with emphasis on molecular characterization of the MO have been poorly studied in tropical regions with scarcity of detailed studies that assess the characteristics and chemical composition of OM and its influence in the podzolization process. The main goal is to characterize the MO of Spodosols in order to obtain information about the chemical composition of organic substances that allow a more comprehensive approach on the formation processes and elucidate the lateral and vertical variation of OM evolution, and consequently, Spodic horizons in Ilha Comprida. To obtain information about the OM composition will be used analytical methods as pyrolysis associated to gas chromatography / mass spectrometry (Pi-CG/EM) and spectroscopic methods such as Nuclear Magnetic Resonance (NMR) for determining the properties of OM. For the analysis of data generated by Pi-CG/EM method, which is currently a technology "edge" will require training and supervision by a specialist in specific programs for such, and will need to use multivariate statistics to obtain results comparative samples and other relevant to this soil. Studies of this nature, linked to a better understanding of the process of podzolization are fundamental for the knowledge and conservation of Spodosols. (AU)