We proceeded to an organic-physico-chemical study on the micromycèts of the soil, the important factors of the fertilization of the telluric biotope, in four sites of the region of Biskra (Mʼziraa-soil cultivates by the open cultures, Biskra-cultivated soil by cereal, Tolga-old-palm trees, Doucen-young palm trees), thanks to two soil sampling (in December and April) in course of two years 2014-2015/2015-2016.

A statistical analysis of the data collected by means of an ACP demonstrates that the first year exposed to: Aspergillus sp and yeast Rhodotorula sp are very dominating in all sites, except Biskra which it occupied by Mucor sp [very xerophilous].

However, the second year of sampling is characterized by a dominance of Rhodotorula sp (halophilous et hygrophilous) and Aspergillus sp (halophilous, xérophilous) in Biskra site during winter sampling.

Therefore, in April sampling there are a high density of the species Mucor sp and Aspergillus sp in Biskra site, and by Aspergillus sp at Mʼziraa site, then we can concluding that the genus of Aspergillus, Rhodotorula and Mucor contains the very abondonated micromycèts (phytopathogens and biofertilizers) in calci-magnésic soils into the region of Biskra.

Keywords: Aspergillus sp, Rhodotorula sp, Tolga, Doucen, Biskra.