NO₃^- accumulation in the soil would trigger N losses through runoff, leaching and N₂O emission. It is, therefore, of particular importance to take appropriate nitrogen (N) management strategies to reduce soil NO₃^- accumulation, and hence to enhance N use efficiency and reduce N losses to the environment. Application of nitrification inhibitor (NI) has been demonstrated to be effective in reducing soil NO₃^- concentration, NO₃^- leaching and N₂O emission, and simultaneously increasing crop yield. However, there is an indisputable fact that NI application increases ammonia (NH₃) emission and causes NI contamination. As a matter of fact, soil NO₃^- concentration varies with NO₃^- generation (nitrification) and consumption (assimilation) rates in aerobic conditions. Under the influence of the viewpoint that soil microbes prefer NH₄ -N for their growth, it is commonly held that soil microbes rarely use NO₃^- in farmlands. Consequently, the study on processes of soil microbial NO₃^- assimilation has been neglected to a certain extent. The process of soil microbial NO₃^- assimilation is found to be unique in advantage. It turns NO₃^- into microbial biomass N for temporary storage before mineralization to be available to crops for a longer season or crops in the following season. There is no doubt that soil microbial NO₃^- immobilization is stimulated by specific extraneous C input, which deserves more attention in future studies concerning how to reduce soil NO₃^- accumulation. Further studies should primarily focus on the following several aspects: (1) to elucidate mechanism of the microbe driving NO₃^- assimilation under elevated C availability, (2) to explore how to control microbial assimilation and remineralization of NO₃^- to match soil N supply with crop N demand and reduce N losses, and (3) to explore how to avoid stimulating denitrification and associated N losses while enhancing microbial NO₃^- assimilation under the condition of sufficient C supply.