Microdiagnostics of initial pedogenesis on a phosphogypsum dump

Abstract

This paper presents the results of the study of initial pedogenesis on phosphogypsum dump rocks under dry steppe bioclimatic conditions (Balakovo, Saratov Region, Russia). It was shown that a soil crust about 3 cm thick was formed at the dump surface as a result of natural pedogenic processes over a period of 20-30 years. Such soil crusts act to cement the surface and protect the dump material from deflation and water erosion. The crust was shown to consist of two parts that can be distinguished by morphological features: an upper part (about 2 cm thick) of a more firmly bound material more grey in colour and a lower part (about 1 cm thick) with a looser consistency and lighter colour. The structural organisation is primarily determined by the presence of live roots of grasses and mosses, which is characteristic of a biogenic crust. The two parts of the crust were characterized at both macro- and micro-scales, by use of thin sections and tomographic imagery. The presence of humification features and porosity observed within the crust allowed for the diagnostics of initial pedogenesis.