Fast pedogenesis of tropical Technosols developed from dolomitic limestone mine spoils (SE-Brazil)

Abstract

Technosols occur wherever human activity led to the construction of artificial soils. Attention has been given to the use of these soils as a strategy for mine reclamation. Nevertheless, research on pedogenesis of Technosols in the tropical environment is still missing. This study evaluated the pedogenetic evolution of artificial soils constructed with dolomitic limestone mine spoils, where sugarcane has grown over two (SC2) and six years (SC6), and pasture has grown over 20 years (P20). Chemical and physical soil characterization as well as detailed macro and micromorphological description were conducted. We observed specific pedogenetic processes, mainly evidenced by the micromorphological investigation, such as: pedoplasmation, rubification and melanization. Pedoplasmation led to aggregation and was more intense after 6 years of pedogenesis. Dissolution of iron nodules and pyrite oxidation caused rubification and color development especially after 6 years. In P20, the predominant pedogenetic process was melanization. High contents of organic carbon (>7.4%) were observed throughout this profile, due to the addition of organic matter by roots and the organo-mineral interaction probably mediated by calcium. As a result, this profile presented structure and color equivalent to a mollic horizon. Our data evidenced the high intensity of different pedogenetic processes and the fast evolution of tropical Technosols highlighting its potential for land reclamation.