Caracterização de Latossolos em topossequência e de Argissolos em hidrossequência com apoio de sensores próximos

Abstract

The proximal sensors are drawing attention in many pedological studies by reducing costs and time of analyses, without generation of residues, being analyses environmentally-friendly. Studies that use combination of proximal sensors for pedological investigations are still scarce in tropical regions. This makes necessary in-depth studies about these sensors arrangement for obtaining robust results for soil profile studies. We studied two different areas with aid of sensors and other equipment. The first one deals with a toposequence where less weathered soils were expected. However, Oxisols were found on a steep slope, classified as Typic Hapludox (P1 and P2, upper and middle third respectively) and Xanthic Hapludox (P3, lower third), according to Keys of Soil Taxonomy (USST). In the Oxisols, the elemental contents varied on the toposequence and among the soil horizons. The altitudinal concordance of summits observed in the more elevated surrounding areas indicates a flat paleorelief, helping to explain this not typical occurrence of very weathered-leached soils in hilly tropical landscapes. The portable X-ray fluorescence (pXRF) spectrometer complemented the results obtained by traditional analyses (e.g., chemical, physical). The soil color influenced the reflectance captured by Vis-NIR, assisting in the characterization of these highly weathered soils. The second area was composed of three different Ultisols, Typic Rhodudults, Typic Hapludult, and Inceptic Hapludults (USST classification) on an undulated slope. In this area, the drainage regime varies according to the profiles, on which PA is the most limited. The digital morphometrics approach enabled to assess the elemental variability on the Ultisols that seems homogeneous visually. In addition to the color of these soils, it was possible to discern them by the elemental contents, magnetism, and mineralogy. In each study area, we observed that the factor that more intensely influenced the profiles was the position on the landscape. The sensors used brought robustness to the obtained results, helping characterize these Oxisol and Ultisol profiles under a lesser explored approach in previous studies of tropical regions.