Amorphous silica fertilization ameliorated soil properties and promoted putative soil beneficial microbial taxa in a wheat field under drought

Increasing water demand from agricultural practices and environmental pollution caused by the intensive use of agrochemicals are among the most pressing issues concerning agriculture sustainability. The use of amorphous silica (ASi) as soil amendment can represent a valid alternative measure to cope with the upcoming challenges of intensifying drought stress and to decrease the need for phosphorus fertilizer application. In this study, we investigated the impact of two levels of ASi fertilization on edaphic characteristics and the rhizosphere microbiota of winter wheat through a field experiment conducted during a drought period. Since plant phenology plays a pivotal role in shaping crop microbiota, our research explored the response of rhizosphere bacteria and fungi to ASi fertilization at three distinct stages of plant growth: pre -planting, tillering, and ripening. Firstly, our results clearly showed an ameliorative effect of ASi fertilization on edaphic properties, with notable improvements in soil moisture, particularly at higher ASi fertilization levels. Secondly, we observed that ASi exerted a profound influence on the wheat microbiota, resulting in varying effects on bacterial and fungal communities. Specifically, in comparison to the control treatment, bacterial community composition exhibited greater sensitivity to ASi fertilization during the tillering stage, whereas the fungal microbiota displayed increased dissimilarity during the ripening stage. Notably, ASi fertilization promoted in the wheat rhizosphere the enrichment of plant -beneficial microbes with putative plant -growth promoting and biocontrol capabilities. Overall, our findings highlight the efficacy of ASi fertilization as an effective measure to mitigate drought stress, enhance the availability of plant nutrients, and promote the enrichment of beneficial microbes within cereal cropping systems.