Abstract
Although organic amendment has been widely accepted to be capable of facilitating soil agglomeration in coastal salt-affected soils, quantitative characterization with respect to how abiotic and biotic components drive the formation and stabilization of soil aggregates remains largely unexplored and poorly understood. In the current study, wet-sieving, Miseq sequencing, etc., were employed to study the impacts of different application amounts of sewage sludge on soil aggregates, physicochemical properties, enzyme activities, and microbial core microbiomes in coastal saline soils. The results indicated that sewage sludge was conducive to soil agglomeration, abiotic constraint alleviation, microbial activity enhancement, and bacterial and fungal community stabilization and functionalization. The results derived from variation partitioning analysis and the structural equation model showed that elevated soil organic carbon and mitigated salinization were dominant abiotic factors that directly drove the stabilization and functionalization of bacterial and fungal microbiomes. In addition, bacterial families (e.g., Xanthomonadaceae, Rhodospirillaceae, and Micrococcaceae) and fungal genera (e.g., Trichoderma, Cephaliophora, Mortierella, and Penicillium) were potential functional microbial populations related to soil agglomeration in organic amended coastal salt-affected soils. Together, these abiotic and biotic agents jointly drove soil agglomeration and totally explained 87% of the variations in soil aggregates. Collectively, this study highlighted the approach and effectiveness of the impacts of organic amendment on soil agglomeration in coastal salt-affected land based on qualitative and quantitative analysis, which would enhance our knowledge with respect to coastal salt-affected soil quality indication and development.