These researches fit into the works coordinated by the Observatoire Hommes-Milieux (OHM) of Bassin Minier de Provence (BMP) and dedicated to vegetal covers and microbial communities of soils. They aim to study the terrestrial deposits of red muds resulting from past and current activities of alumina extraction. Despite the red muds have been extensively studied about their industrial recycling potentials (Klauber et al., 2011), the studies on their environmental effects, especially on the biological component of soils, are far less numerous (Garau et al., 2007, 2011, 2014; Krishna et al., 2014; Lombi et al., 2002) and, furthermore, lacking in the context of BMP. To this date, the various studies available in the literature emphasize the importance of the soil matrix in the modulation of biological responses when it is mixed with red muds. Therefore, this aspect is important to invest at the local scale in the prospect of a potential use of red muds as improvement to soils or to the development of artificial soils for various valuations (agronomy, remediation, rehabilitation). Within this framework, the researches undertaken aim to study the impacts of red mud inputs to soils on their physico-chemical and biological qualities, and especially to test their harmlessness on the biological functions of soils. They also aim to determine, through a multi-scale approach (slag-heap, plot, mesocosm, rhizotron), how and to what extent these tailings modulate the structuring of vegetal and edaphic microbial communities through reciprocal functional relationships.