Amelioration Effects of Pseudomonas fluorescens on Acidified Soil and Subsequent Promotion of Maize Growth

Soil acidification severely restricts agricultural productivity in red soil regions, and microbial remediation represents an eco-friendly restoration strategy. A pot experiment was conducted to investigate the dose-dependent effects of Pseudomonas fluorescens on acidified latosol, maize seedling growth, and rhizosphere bacterial communities. Five inoculation rates were applied (5.5 × 109–3.3 × 1010 CFU pot−1), together with a non-inoculated control. Pseudomonas fluorescens inoculation significantly increased soil pH and base cation contents, reduced exchangeable and hydrolytic acidity, and enhanced soil acid–base buffering capacity. Low to moderate inoculation rates promoted maize photosynthesis, root development, and nitrogen, phosphorus, and potassium accumulation, whereas the highest rate (3.3 × 1010 CFU pot−1) significantly inhibited seedling growth. Bacterial sequencing showed that inoculation reshaped rhizosphere community structure and enriched taxa, including Proteobacteria, Bacillota, Bacillus, and Pseudomonas. Overall, inoculation rates of 1.1 × 1010 and 2.2 × 1010 CFU pot−1 showed the most favorable responses across soil amelioration and maize growth-related traits, suggesting a suitable application range for acidified soil remediation. These results provide preliminary evidence that appropriate application of Pseudomonas fluorescens may contribute to the biological amelioration of acidified soils, although its field-scale effectiveness requires further validation.