Homeostatic evidence of management-induced phosphorus decoupling from soil microbial carbon and nitrogen metabolism

Abstract The theory of microbial stoichiometry predicts proportional coupling of microbial assimilation of carbon (C), nitrogen (N), and phosphorus (P), which is quantified as the homeostasis value (H). Covariation of H values for C, N, and P indicates that microbial C, N, and P assimilation are coupled. Here, we used a global dataset to investigate the spatiotemporal dynamics of H values of microbial C, N, and P across biomes. We found that land-use and management led to the decoupling of P from C and N metabolism over time and across space. We used structural equation modeling (SEM) to show that edaphic factors dominate the microbial homeostasis of P, while soil elemental concentrations dominate the homeostasis of C and N. We confirmed this result using the contrasting factors on microbial P vs. microbial C and N derived from a machine-learning algorithm. Overall, our study highlights the impacts of management on shifting microbial roles in nutrient cycling.