Phosphorus fertilizers coordinate the reduction of  aluminum toxicity and activation of beneficial microbiota to boost Brassica napus  adaptation in acidic soils

Aims Aluminum (Al) toxicity represents a major constraint to crop productivity in acidic soils. Phosphorus (P) fertilization is known to improve crop adaptation to acidic soils, but the underlying mechanisms remain poorly understood in Brassica napus . This study investigated the effects of P applications on B. napus grown in acidic soil, focusing on their potential to alleviate stress and improve plant performance. Methods This study systematically evaluated the adaptability of Brassica napus in acidic soils through a pot experiment with different phosphorus levels. The research covered pH in different soil layers, contents of various aluminum forms, growth at different stages, seed yield and quality of rapeseed, and analyzed the composition and diversity of soil microbial communities among treatments via microbiome analysis, aiming to reveal the regulatory mechanism of phosphorus fertilizer on rapeseed growth and its interaction with soil microbes in acidic soil environments. Results Application of P fertilizers effectively reduced reactive Al³⁺ concentrations in all soil layers, creating a less toxic environment for plant roots. Notably, P amendments induced marked restructuring of soil bacterial assemblages, with significant increases in the abundances of Proteobacteria and Actinobacteria . P fertilizers also substantially increased the dry weight, plant height, and seed yield of B. napus . Conclusion Overall, this research demonstrates the pivotal role of P fertilizers in alleviating Al toxicity, ameliorating soil acidity, and enhancing nutrient availability in acidic soils, thereby boosting crop yield and growth.