Enterobacter asburiae S13 enhances the promoting effect of polyaspartic acid on potato growth by improving rhizosphere nutrient availability and reshaping microbial community

Polyaspartic acid (PASP), as an environmentally friendly fertilizer synergist, has been widely applied in agricultural production. However, the effects of combined application of PASP and microbial inoculants have not been fully investigated. Through integrating pot experiments, soil biochemical property analysis, and microbiome sequencing, this study revealed that inoculation with Enterobacter asburiae S13 improved the plant height (70.83%), stem diameter (38.43%), root length (41.12%), and root-shoot biomass (50.00–45.83%) of potato seedlings under PASP application. Meanwhile, it simultaneously enhanced the contents of ammonium nitrogen (40.00%), nitrate nitrogen (57.70%), available potassium (47.56%), and urease activity in rhizosphere soil. 16S rRNA sequencing showed that Enterobacter asburiae S13 addition enriched beneficial microbial communities (e.g., Paucibacter , Massilia ) and suppressed potential competitive taxa (e.g., Duganella , Pedobacter ). Redundancy analysis (RDA) indicated that available potassium and ammonium nitrogen were the core factors driving microbial community structure changes. These results elucidated the causal relationship between rhizosphere nutrient dynamics and microbial community reshaping under the combined application of PGPR and PASP, providing theoretical and technical support for sustainable fertilization strategies in agriculture.