Effects of Lake Erie dredged material on microbiomes in a farm soil of northwestern Ohio

Dredged materials are often considered as candidates for replenishing lost topsoils in the watersheds of rivers and lakes. This study aimed to investigate the impacts of Lake Erie dredged material on the microbial community in a farm soil of northwestern Ohio. Dredged material from the Toledo Harbor, OH was mixed with a local farm soil at ratios of 0:100, 10:90, 20:80, and 100:0 for soybean growth in a greenhouse for 123 days and was subject to 16S rRNA gene sequencing. α-Diversity analysis revealed that although the original dredged material hosted a highly diverse microbiome, soils blended with the dredged material had similar levels of bacterial diversity to 100% farm soil throughout the experiment. β-Diversity analysis demonstrated that, given the same plant status, that is, with or without soybean, blended soils had similar bacterial communities to 100% farm soil during the experiment. Furthermore, by the end of the experiment, all soils with soybeans merged into one cluster distinctive from those without the plants, indicating that the growth of plants played a dominating role in defining the structure of soil microbiomes. The majority (73.8%) of the operational taxonomy units that were unique to the original dredged material were not detected by the end of the experiment. This study demonstrates that up to 20% of the dredged material can be safely blended into the farm soil without distorting the microbial communities of the latter, implying a potential beneficial use of the dredged material for topsoil restoration.