The ECOFUN-MICROBIODIV project aimed at developing and evaluating innovative tools to estimate the ecotoxicological impact of low dose pesticides used in agriculture on soil functional microbial biodiversity. It proposed to estimate the impact of sulfonylurea herbicide on soil microbial biodiversity and functioning. This project is based on an interdisciplinary approach conducted at different scale, from the field plot to the greenhouse, to test in corn crop the impact of chemical weeding compared to mechanical. The impact of chemical or mechanical weeding on corn crop production and weeds dynamics will be estimated. The fate of sulfonylurea in the different soil will be study in order to determine the exposure of the soil microbiota. This represents a key explaining parameter conditioning the ecotoxicological impact of the pesticide. The ecotoxicological impact of the chemical weeding will be estimated using standard methods aiming at studying the size, diversity and the activity of the soil microflora. In addition, new methods based on direct soil DNA extraction (under standardization at the ISO level) and further amplification by polymerase chain reaction will be applied to determine the impact of sulfonylurea on (i) the global structure and abundance of both fungal and bacterial communities and on (ii) the structure, abundance and activity of functional communities involved in C and N cycles as well as in the formation of the endomycorhizal symbiosis. A new biomarker specific for sulfonylurea will be developed by targeting the acetohydroxyacid synthase gene coding for the enzyme inhibited by this herbicide. In addition, the impact of sulfonylurea on soil microflora adaptation will be estimated by isolating and characterizing bacterial strains able to degrade this herbicide. This interdisciplinary project will furnish new insight in the ecotoxicological impact of low dose pesticide on soil microflora functional biodiversity.