Effects of sewage sludge ash as a recycled phosphorus source on the soil microbiome

Ash byproducts have been used as soil amendments to recycle nutrients and modify soil properties such as pH or density. Interest in these practices has continued with increasing emphasis on sustainability, particularly regarding phosphorus reuse from incinerated sewage sludge. Given recent advancements in microbial analyses, the impacts of these practices can now be studied from the soil microbiome perspective. Next-generation DNA sequencing technologies provide information about the taxonomic composition of bacterial, archaeal, and fungal communities in a complex environment like soil. In this review, we discuss the results of microbial analyses of soils amended with recycled ash products, including a pilot study of sewage sludge incinerator ash as a phosphorus source. These results indicated that changes in soil microbial community composition require high amounts of amendment for detectible effects. Future research efforts could include more focused investigations into phosphorus-related microorganisms, such as phosphorus-solubilizing bacteria or polyphosphate-accumulating organisms.