Fertilization improves tobacco yield and quality by regulating soil microorganisms

Fertilization is vital for crop yield and quality in agriculture. Proper fertilization improves crop yields and quality, whereas inadequate fertilizer use can have negative effects. Soil microorganisms play an important role in fertilizer efficiency. The present 20-year experiment (2004–2024) evaluated the impacts of three fertilization strategies (no fertilizers, CK; chemical fertilizers, CF; and a mixture of chemical and organic fertilizers, MCF) on tobacco leaf yield, proportion of high-grade leaves (PL), and soil microbe communities. Compared with CK, crop yield increased by 75.07 % (MCF) and 24.58 % (CF) after continual fertilization for 20 years. Similar trends were also observed in PL. MCF thus achieved higher crop yield and quality than CF. Simultaneously, the MCF-amended soil exhibited a pH of 7.61, markedly higher than the soil with CF (pH 7.14), suggesting a lower degree of soil acidification. MCF also significantly enriched beneficial bacteria, including Proteobacteria and Actinobacteria , and their abundances were positively correlated with crop yields and the activity of key soil enzymes such as catalase (CAT) and urease (URE). Metagenomic analysis found that MCF augmented microbial energy metabolism pathways (for example, oxidative phosphorylation). Structural equation modelling demonstrated that MCF-induced shifts in soil nutrient supply and microbial communities collectively contributed to improved crop yield and quality. Therefore, MCF enhances soil productivity through improving nutrient recycling and optimizing microbial communities in soil, providing a sustainable strategy for maintaining soil health in intensive agriculture.