Edaphic variables influence soil bacterial structure under successive fertilization of Paulownia plantation substituting native vegetation

Purpose Paulownia is the fastest-growing timber species all over the world which depended on exogenous nutrient input and scattered in the subtropical region of China. Practical experience proved that balanced fertilization can provide a rational nutrition supply for Paulownia cultivation by affecting soil microorganisms. However, there have been no rigorous studies on the effects of fertilization and edaphic variables on soil community structure and functions of Paulownia plantation in the subtropical region. Materials and methods We conducted a field plot experiment with four fertilization length levels of Paulownia plantation (abbreviated as 1-, 3-, 10-, and 13-yr) and a nearby native evergreen broadleaf forest (abbreviated as reference forest) to study the effects of the different fertilization lengths between them on soil bacterial community and the relationship with edaphic variables based on high-throughput sequencing and redundancy analysis. Results The results showed soil organic carbon, macronutrients, and boron in plantation were significantly higher than that in the reference forest, while fertilization treatments significantly increased Shannon and Heip indexes by up to 14.37 and 75%, respectively. Chloroflexi and Nitrospiare relative abundance in the Paulownia plantation was significantly lower than in the reference forest, which implied that fertilization treatment significantly promote nitrogen transformation processes, whereas Firmicutes showed the opposite trend. Soil organic carbon, nitrate-nitrogen, total potassium, and available boron are the key factors affecting bacterial communities as confirmed by Spearman’s correlation analysis and redundancy analysis. Conclusions Our study stressed that fertilization duration is the main driving force for the improvement of bacterial community diversity and nitrogen cycling function, and major achieved by affecting edaphic variables.