Each year, around 1.5 million tons of sediments are excavated from the federal navigation channels at Toledo Harbor, which used to be disposed in an open lake placement area in Lake Erie. After the ban on open water disposal, utilizing this dredged material (DM) as a soil amendment became an attractive approach to managing DM disposal issues. Previous research has shown the DM can improve soil physiochemical properties in greenhouse settings (Brigham et al., 2021; Gautam et al., 2024; Gautam et al., 2025). This study aimed to characterize the taxonomic diversity of microbial communities in the fields amended with DM, using 16S rRNA analysis. Among the three organically managed fields, plot 1 and plot 3 received 40 tons per acre and 80 tons per acre of DM, respectively, and plot 2 received no DM (control treatment). Alpha diversity metrics (Shannon index) did not show significant differences among the plots. (p > 0.05). Principal component analysis (PCoA) based on Bray-Curtis dissimilarity revealed clear separation of microbial communities among the three treatments. Each treatment formed a distinct cluster in the emperor plot, indicating compositional differences in microbial communities. Additionally, PICRUSt2 analysis revealed positive associations between phosphorus-cycling genes (phoD and phytase) and soil calcium, indicating enhanced phosphorus mineralization.
