Sustainable agricultural practices are sought to be implemented across Europe and worldwide to improve soil nutrient cycling processes which includes nitrogen (N) and phosphorus (P) and to reduce loss of nutrients through leaching, surface runoff and gaseous emissions. Indeed, EU targets have been set to improve nutrient use efficiencies (NUE) by 50% by 2030. A key aspect in achieving such a goal is to improve soil carbon (C) stocks and soil organic matter (SOM). It is assumed that by reversing the widespread loss of soil C in Europe’s soils, nutrient-use efficiencies may be improved through the betterment of soil multi-functionality. Soil microbiota will play key role in sustainable plant nutrient supply as they are key drivers in making soil nutrients N and P plant available, while at the same time immobilise excess N and P that is at risk of loss to ground- and surface-waters. Increasing soil C stocks sustainably can be achieved by including organic materials of waste origin from the circular economy model. This will reduce linear economy dependencies and engage the circular economy for the sustainable supply of not only C, but also vital plant nutrients N and P. This session aims to advance our limited understanding of the relationships between soil C and the microbial activities in soil that decide whether plant nutrients N and P are made available or are immobilized. Optimization these processes would allow to improve NUE by more targeted supply of plant nutrients through microbial activities, while at the same time excess nutrients can be prevented from leaching into the ground water by microbial immobilization. The use of circular economy fertilizers with substantial C content may provide multiple benefits by reducing the need for non-renewable linear economy fertilizers while at the same time promote microbial driven NUE. Further research in soil stoichiometry, microbial driven NUE and circular economy fertilization is needed to make the gains in sustainable agriculture that is needed in Europe and the rest of the world.