Crop-specific and microbially-mediated impacts of alternative agricultural amendments on plant performance

The goal of this study was to investigate how biosolids and reclaimed water spiked with increasing environmentally-relevant contaminant concentrations, affect the growth performance of three agriculturally relevant crop species: lettuce (Lactuca sativa), radish (Raphanus sativus), and green pea (Pisum sativum). We directly exposed each crop species to amendments and contaminants and quantified plant trait responses, including germination, survival, and biomass, testing whether increasing contaminant levels altered plant performance and whether these responses varied by crop species. We characterized soil microbiome diversity and composition one week post planting and harvest to assess temporal shifts related to amendment and contaminant exposure and test for associations between these shifts and plant performance. We assessed the legacy effects of amendment and contaminant exposure on the microbiome's ability to support plant growth by inoculating pea plants with soil slurries containing microbiomes from the first experiment. By disentangling the direct and microbially mediated effects of amendments across multiple crop species and contaminant concentrations, our study provides critical insight into the ecological trade-offs of using biosolids and reclaimed water in agriculture - highlighting the importance of microbiome dynamics in shaping plant responses to environmental contaminants.