Tomato plants rather than fertilizer drive rhizosphere microbial community structure

The synthetic fertilizer production is associated with a high environmental footprint, which is aggravated by leaching as compounds are typical dissolving rapidly. We tested struvite and a commercially available organic fertilizer as recovered nutrients with a slower release pattern, as promising alternatives for synthetic fertilizers. Using both fertilizers as a nitrogen source, we conducted a rhizotron experiment to test their effect on plant performance and nutrient recovery in juvenile tomato plants. Plant performance was significantly improved when organic fertilizer was provided, promoting higher shoot biomass. Since the microbial community influences nitrogen availability for plants, we characterized the root-associated microbial community structure and functionality. Analyses revealed distinct root microbial community structures when different fertilizers were supplied. However, plant presence significantly increased the similarity of the microbial community over time, regardless of fertilization treatment. Additionally, the presence of the plant significantly reduced the ex situ potential ammonia oxidation rates, implying a possible role of the rhizosheath microbiome or nitrification inhibition by the plant. Our results indicate that nitrifying community members are impacted by the type of fertilizer used, while tomato plants influenced the potential ammonia-oxidizing activity of nitrogen-related rhizospheric microbial communities. These novel insights in interactions between recovered fertilizers, plant and associated microbes can contribute to more sustainable crop production