Variation of soil attributes along a sandstone-gneiss toposequence in southern Amazonas, Brazil

Abstract

Soil-landscape relationships in natural environments can provide helpful insights into soil suitability and limitations and necessary changes regarding agricultural land use and management. The objective of this work was to verify soil variations along a sandstone-gneiss lithological toposequence in the western Amazonian region of Brazil. Within this topolithosequence, the following soil profiles were sampled: CAMBISSOLO HÁPLICO (Dystric Leptic Cambisol), NEOSSOLO REGOLÍTICO (Cambic, Lithic, Leptosol), NEOSSOLO QUARTZARÊNICO (Dystric Regosol), PLINTOSSOLO PÉTRICO (Petric, Plinthosol), and ARGISSOLO AMARELO (Chromic, Abruptic, Acrisol). These profiles were located on the following slope segments: interfluve (P1), convex creep slope (P2), transportational midslope (P3), colluvial footslope (P4), and alluvial toeslope (P5). Soil analyses included physical and chemical attributes. The influence of the landscape on soil attributes was evaluated through randomness test, run charts, Pearson correlation, and Tukey test at a 5% significance level. Soil chemical properties were more sensitive to slope-related variations, with increased chemical quality in P2 for both horizons. Soil organic matter proved to be crucial for improving the chemical and physical quality of sandstone soils.