Recycled Phosphorus Bioamendments from Wastewater Impact Rhizomicrobiome and Benefit Crop Growth: Sustainability Implications at Water-Food Nexus

Phosphorus recovery through enhanced
biological phosphorus removal
(EBPR) processes from agricultural wastes holds promise in mitigating
the impending global P shortage. However, the complex nutrient forms
and the microbial augments, expected to exert a profound impact on
crop rhizomicrobiome and thus crop health, remained unexplored. In
this study, we investigated the impacts of EBPR biosolids on crops
growth and rhizomicrobiome in comparison to chemical fertilizer and
Vermont manure compost. Our findings revealed that EBPR biosolid augmentation
promoted the best maize shoot growth traits with the least nutrient
deficiency, evidencing its agricultural benefits. Biosolid augmentation
significantly impacted the rhizomicrobiome with decreased biodiversity
but higher activities with enriched taxa capable of utilizing various
carbon sources. The novel single-cell Raman spectroscopy phenotyping
technique uncovered the surprisingly high abundance (up to 30%) of
polyphosphate-accumulating organisms (PAOs) in the rhizosphere and
their distinctive variations in different biosolid amendments. Furthermore,
the interactions between EBPR-derived PAOs such as Candidatus Accumulibacter phosphatis and soil native plant growth promoting
rhizobacteria highlighted the previously overlooked status and yet-to-be-characterized
functions of PAOs in P cycling. This study provides a novel perspective
leveraging EBPR biosolids to facilitate plant growth with agronomic
benefits, thereby contributing to more sustainable and ecologically
responsible agricultural practices.