QUELS ROLES POUR LES MICROORGANISMES DU SOL DANS LA SEQUESTRATION DU CARBONE EN ZONES ARIDES DE OUARGLA

Abstract

Soil provides ecosystem services, including storage of CO2 and protection against global warming. The Ouargla region is characterized by high temperatures, low and irregular rainfall, sparse vegetation and soils poor in organic matter. Nevertheless, the soil remains a favorable environment for macros and microorganisms, which tolerate this deficit, even if this microbial biomass represents only 2 to 4% on average of organic carbon. It intervenes for the renewal of organic matter in the soil. The aim of this work is to study the impact of microorganisms on organic carbon storage in different soil landscapes of the Ouargla region. For this study, 7 stations of different pedo-sequences were chosen (saline soil, reg soil, clay soil…etc). After taking a soil sample at 30 cm, the samples underwent microbiological analyzes for the enumeration of bacteria and fungi, fumigation-extraction, and physicochemical analyzes. The results of enumeration of the main microbial groups in bacteria and fungi showed the predominance of bacterial microflora, followed by fungal microflora at higher values in cultivated soil and those of Sebkhat. The identification of fungal species according to the determination keys allowed us to identify Alternaria alternata, Rhizopus sp, and Aspergillus niger, as well as yeasts. The fumigation-extraction results show that the microbial carbon values are higher in Sebkhat N’Goussa, gypsum soil of Frane and in cultivated soils. It is at these stations where high levels of organic carbon and organic matter are recorded. We can say that microorganisms play an important role in carbon sequestration. They mineralize microbial residues and provide carbon to the stable organic matter fraction of soil