Global patterns and drivers of soil microbial nitrogen and phosphorus use efficiency

While nutrient use efficiency of soil microorganisms, the proportion of assimilated nutrients allocated into biosynthesis rather than invested in mineralization, is a critical microbial functional trait, its global patterns remain poorly quantified. Here, we estimate microbial nitrogen use efficiency (NUE, n = 2012) and phosphorus use efficiency (PUE, n = 3419) across terrestrial ecosystems using the ecoenzymatic stoichiometric approach. Globally, NUE (mean 0.60) is nearly twice as high as PUE (0.35). Soil organic carbon (SOC) is the strongest predictor of both, with higher SOC associated with greater nutrient use efficiency. Spatial upscaling shows that tundra and boreal forest soils have markedly lower NUE than other regions, suggesting high nitrogen investments in nutrient acquisition in cold ecosystems, whereas PUE is similar across biomes, implying pervasively low phosphorus acquisition capacity. Our study identifies potential nutrient cycling hotspots worldwide and offers critical parameters to refine large-scale predictions of soil carbon and nutrient dynamics.