Study on the Soil Formation Process on the Mining Waste Dumps from Jiu Valley (Romania). A Case Study

The present paper is in fact a continuation of a research effort started approx. 16 years ago, and whose main purpose is to follow the process of transformation of rocks from coal mining waste dumps into a fertile soil. Thus, during 2022, a new sampling campaign was carried out from the Petrila waste dump, which was later subjected to laboratory tests in order to determine the main characteristics that define the soil. These new data can be seen as the result of a periodic monitoring process and they complement the systematic study carried out between 2006 and 2011 (this study also included research related to the ecological succession of the phytocoenoses present on the Petrila dump). According to these latest analyses, the soil formation process is an active one, relatively slow, being highlighted by the increase in the content of nutrients and organic substances in the composition of the dumped material compared to the previously determined concentrations, as well as by the increase in the total and physiologically useful thickness of the soil layer. The results of this study are important for the next period, when the last 4 active dumps in Jiu Valley will be put into conservation, providing relevant information regarding the pedogenesis process that takes place on these dumps, under the exclusive influence of natural factors.