Title: Flue gas desulfurization gypsum amelioration affects the salinealkali soil microbial community on the temporal scale

Abstract

Although the physicochemical processes of salinealkali soil amelioration via flue gas desulfurization (FGD) gypsum have been well substantiated, the underlying mechanisms of soil microbial community succession and feedback on the temporal scale of amelioration remain unclear. To elucidate this mechanism, we investigated the microbial community response to the physicochemical properties change with salinealkali soil ameliorated by FGD gypsum for 1 year, 3 years, and 10 years (the corresponding bare salinealkali soil was used as the control). With increasing years of FGD gypsum amelioration in salinealkali soil, the proportion of homogeneous selection (determinism process) in bacterial and fungal communities significantly increased from 37.5 % to 50.3 % and from 10.0 % to 31.8 %, respectively, but the proportion of dispersal limitation (stochastic process) significantly decreased. Thus, the microbial species composition and community structure were significantly changed, thus increasing microbial community β-diversity and ecological co-occurrence network complexity with increasing years of amelioration, as did the predict functions of prokaryotes in the dark oxidation of sulfide and sulfur compounds. Furthermore, the random forest and structure equation modules indicated that the changes in bacterial and fungal community assembly processes, structures, and co-occurrence networks were dominated by soil organic carbon, dissolved organic carbon and nitrogen, exchangeable sodium percentage, SO₄^2-, HCO₃^-, and pH. Our findings suggest that the soil microbial community succession process and complexity increase with increasing years of FGD gypsum reclamation by mediating the salinity and soil available carbon and nitrogen content in salinealkali paddy soils on the temporal scale.