Temporal dynamics drive soil resistome variation more strongly than warming or biocide application

Abstract Antibiotic resistance is a major global health concern. Understanding how climate change-related factors can influence antimicrobial resistance patterns in the environment is essential for developing efficient One Health-based resistance control strategies. In this study, under field conditions, we assessed the combined effects of soil warming and biocide (herbicide, fungicide, insecticide) application on soil physicochemical and microbial parameters, potato yield, and the soil resistome using the targeted metagenomics ResCap platform to quantify antimicrobial resistance genes (i.e., antibiotic resistance genes, metal resistance genes, biocide resistance genes, relaxase genes). To our knowledge, this is the first field study specifically designed to investigate the effects of the interaction between agricultural practices (i.e., biocide application) and soil temperature on the environmental resistome, thereby providing insight into the potential contribution of agroecosystems to the reported link between rising air temperatures and the increasing prevalence of antibiotic resistance. Our results indicate that neither soil warming nor biocide application were key factors affecting the observed variation in the abundance of resistance genes. Instead, the temporal dynamics during the growing season, as reflected by the observed differences between soil sampling times, was the variable with the strongest effect on soil resistome dynamics. These findings highlight the importance of studying the temporal dynamics during the growing season when evaluating how agricultural practices and climate change-related factors can influence the environmental resistome.