Bacteria in soil are very diverse, very numerous, and functionally important, and have historically been an important object of research by Canadian microbiologists. Only a small fraction of bacteria in soils are amenable to culturing in the laboratory, limiting the ability to study these organisms. Canadian scientists have contributed to the development and implementation of both nucleic acidbased and chemical biomarker-based methods now widely used for assessing soil microbial biodiversity without the need for isolation and cultivation. Pesticide degradation, and the cycling of nitrogen in soils are used here to illustrate the significance of bacterial biodiversity to soil functions relevant to human and environmental health, and crop production . There remains much to be discovered about the genetic and functional biodiversity of soil bacteria, and much to be gained from this knowledge. A number of recommendations are made for future research in soil bacteriology. Key words: Soil quality, bacteria, microbial biodiversity, pesticide biodegradation, nitrogen cycling.