Balanced NPK fertilization enhances maize yield and shapes rhizosphere bacterial communities in purple soil: evidence from a ten-year field experiment

Balanced fertilization with nitrogen (N), phosphorus (P), and potassium (K) plays a pivotal role in sustaining maize productivity and shaping soil-microbe interactions. However, the integrated effects of long-term fertilization on crop performance, soil nutrient dynamics, and rhizosphere bacterial communities in purple soils remain unclear. In a 10-year field experiment in purple soil, conducted under a randomized complete block design (RCBD) with three blocks, we evaluated the effects of different fertilization regimes on maize growth and yield, soil physicochemical properties, and bacterial community composition using 16 S rRNA gene sequencing. Nitrogen-containing fertilizer treatments (NPK, NK, NP) markedly enhanced grain yield, shoot and root biomass, and root morphological traits compared with unfertilized (CK) and PK treatments, with balanced NPK fertilization delivering the highest performance. Fertilization significantly influenced soil nutrient availability, with NPK maintaining more stable nutrient levels over time. Microbial analyses revealed that rhizosphere communities were more responsive to fertilization than bulk soil communities, with N availability driving diversity shifts and community separation. Key taxa, including Variovorax, Microscillaceae, Lysobacter, and Dyadobacter, were enriched in N-fertilized soils and positively correlated with grain yield and N uptake. Collectively, these findings demonstrate that balanced NPK fertilization, particularly nitrogen input, enhances maize productivity by simultaneously improving soil fertility and fostering beneficial rhizosphere microbial assemblages, offering a basis of sustainable nutrient and microbiome management in purple soil.