Variations in Soil Properties Rather than Functional Gene Abundances Dominate Soil Phosphorus Dynamics under Short-Term Nitrogen Input

Background: and aims Microorganisms play a vital role in regulating soil phosphorus (P) dynamics in terrestrial ecosystems. However, how nitrogen (N) inputs trigger the functional traits of P transformation-related microorganisms to affect P fates in soil needs to be explored further. Our aims were to reveal the soil microbial functional profiles for P turnover in response to N input and to explore the relationships between soil P dynamics, soil properties and functional genes. Methods: We collected soil samples from field experiments with three levels of N input over three years in an alpine meadow of the Qinghai-Tibet Plateau to determine soil P dynamics and other properties and functional genes via metagenomics. Results: The soil available P and microbial biomass P were significantly affected by N inputs and significantly associated with soil properties (including soil pH, alkaline phosphatase activity, and soil total N and NO 3 - -N contents). Meanwhile, high N input decreased the relative abundance of the pstS gene, and low N input reduced the relative abundances of ugpQ and C-P lyase genes. The pstS gene was a determinant of soil microbial biomass P and significantly correlated with soil pH. Moreover, Alphaproteobacteria with C-P lyase and Actinobacteria related to alkaline phosphatases and phosphate-specific transport were the most abundant taxa but not affected by N input. Conclusions: We found relationships between the pstS gene, microbial biomass P and soil pH, and the microbial functional gene abundance was less important than soil properties in regulating soil P dynamics under short-term N inputs.