Impact of Maize Growth Stage on Soil Bacterial Communities and Functions in Dryland Under P Fertilization: a Comprehensive Analysis

Since 2015, China has implemented a plan for chemical fertilizer reduction. However, the changes in soil bacteria under reduced phosphorous (P) fertilization remain unclear. This study aimed to assess the responses of rhizosphere soil bacterial communities and functions to P inputs. A maize field experiment with different P input rates (control (CK, no P input), farmers’ practice (FP, 52.4 kg P ha⁻¹), and reduced P input (RP, 30.6 kg P ha⁻¹)) was conducted on the Chinese Loess Plateau. The maize growth and rhizosphere bacterial communities and functions at different growth stages were evaluated. RP decreased soil available P but did not affect maize biomass. The bacterial diversity and community compositions at the V5 stage were different from those at the V3 and V4 stages. Only a few bacterial taxa were changed by P input, but community structures were different among the different treatments and growth stages. No changes in network connectivity were observed between RP and FP. Additionally, the relative abundance of phosphate-solubilizing bacteria (PSB) exhibited a decline throughout the growth time and were higher in RP at the V3 stage. However, a high abundance of P metabolic genes was observed at the V5 stage. The maize growth stage drove the changes in rhizosphere soil bacterial composition and functions; reduced P fertilization slightly altered the bacterial community but increased the abundance of PSB at the V3 stage, and thus supplied more P to maize in the early stage of growth. Therefore, the management of reduced P fertilization could be applied to maize.