Phosphate-cycling activity of the soil microbiome in response to the recycled phosphates struvite and vivianite

Abstract

Recycling phosphorus from waste streams is crucial for meeting rising fertilizer demands without depleting finite resources. Struvite and vivianite, recovered from wastewater treatment processes, have demonstrated potential as fertilizers. However, the impacts of these recycled phosphates on soil microbial communities, particularly those involved in phosphate cycling and their potential to solubilize struvite and vivianite, are poorly understood. This study examined the effects of struvite and vivianite amendments on soil microbial community composition and activity across diverse management regimes using soil incubation. The microbial community was assessed by 16S rRNA gene and ITS amplicon sequencing, and the phosphate-cycling capacity of the soil microbial communities was assessed via phosphatase activity and solubilization assays targeting inorganic phosphates, including tricalcium phosphate, struvite and vivianite. While the overall composition of the soil microbial community remained largely unchanged following recycled phosphate amendment, specific microbial taxa were enriched, reflecting the chemical properties of the amendments. Struvite application resulted in the enrichment of Nitrosospira and Nitrospira populations, while vivianite amendment favored Streptomyces and Mortierella. Despite these taxa-specific enrichments, all phosphate-cycling activity remained stable following vivianite amendment across all soil management types. Struvite amended soils exhibited a soil-specific dip in phosphate solubilization activity at the beginning of the experiment, but all phosphate-cycling activities were unchanged at the end of the soil incubation. These findings indicate that, independently of soil management regime, struvite and vivianite amendments maintain stable phosphate-cycling activity within soil microbial communities.