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Characterizing the impact of soil phosphorus on soil organic matter stabilization
Phosphorus (P) is an essential nutrient for life, but its role in mediating important biogeochemical cycles is often overlooked or misunderstood due to the emphasis on carbon (C) and nitrogen (N) cycling in terrestrial ecosystem science, especially in temperate regions. Furthermore, we have incomplete understanding of how soil function is regulated by P, especially in regards to keystone processes like decomposition as well as soil organic matter formation and stabilization. Filling this scientific gap is critical because in order to improve our predictive understanding of biogeochemical cycles, further investigation is needed on P capacity to mediate the cycling of C. Leveraging a decade-long P enrichment experiment where the cycling of P was altered by phosphate fertilizer and/or by raising pH with lime, this experiment has amassed evidence that microbial function has been significantly altered due to the treatments, which may explain observed decreases litter decomposition and the accumulation of soil organic matter (SOM). A EMSL project is an ideal means to address the specific aims: 1) Does P alter organo-mineral interactions and facilitate soil organic matter (SOM) stabilization? 2) How has altering the cycling of P changed the chemical species of soil P and can that explain SOM stabilization? These questions can be answered using the strengths of EMSL to characterize the influence of an altered P cycling on SOM composition, microbial residuals, and organic P associations with SOM formation utilizing their 1) 21 Telsa Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (21T FT-ICR MS) and Orbitrap mass spectrometer and 2) high field Nuclear Magnetic Resonance (NMR). These approaches will advance our understanding of P-mediated organo-mineral interactions and offers a novel opportunity to determine which forms of organic P are preferentially utilized by soil biota responding to increases in soil pH and P availability. Results from this study will: i) help overcome a critical barrier in understanding how P regulates soil C cycling, ii) form a more complete picture on the coupling of C-P biogeochemical cycling and iii) challenge the paradigm that N is unique in controlling ecosystem function by providing evidence that nutrient limitation, in general, may be the underlining mechanism.