Weathering and incipient pedogenesis of Technosols constructed from dolomitic limestone mine spoils

• Autor(a) principal: Ruiz, Francisco
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: http://www.teses.usp.br/teses/disponiveis/11/11140/tde-15052019-163221/
• topic: Alteração mineral; Mineral alteration; Morfologia de solos; Pedogenetic processes; Processos pedogenéticos; Rhizosphere; Rizosfera; Soil morphology; Solos tecnogênicos; Technogenic soils

Technosols combine soils subjected to strong human influence and whose pedogenesis is dominated by its technical origin. They contain a significant amount of materials made, modified or directly transported by human activity, defined as artefacts. Soils formed from technogenic parent materials are spreading and their pedogenesis is still little understood. Given that the sustainable use of the soil resources demands wide knowledge about its genesis, it is necessary to bring further information about Technosols, especially in the tropical environment, where they have been poorly explored. Thus, in this study we characterized three Technosols constructed from dolomitic limestone mine spoils, cultivated with sugar cane (for 2 and 6 years) and pasture (for 20 years). The Technosols experienced a rapid morphological evolution expressed by color development and aggregation. Pedoplasmation, melanization and redoximorphic were the mainly processes occurring in these constructed soils. The combination of grasses over Ca-rich mine spoils triggered organic carbon accumulation and originated a well-developed surface horizon with strong crumb structure and dark color. The rhizosphere played a pivotal role in mineral weathering of the Technosols. Exudation and microbial activity were about two times higher in the rhizosphere than in the bulk soil leading to an enhanced mineral dissolution. Overall, the primary minerals in the rhizosphere presented a medium to high degree of weathering while those from bulk soil were little weathered. Our data indicates that the rhizosphere may provide a favorable biogeochemical environment to the formation of secondary clay minerals. This study evidences that constructed tropical soils may evolve in an accelerated rate of pedogenesis and, thus, are a real alternative for the reclamation of degraded areas, potentially restoring original soil ecosystem services.