Response of Soil Bacterial Communities and Potato Productivity to Fertilizer Application in Farmlands in the Agropastoral Zone of Northern China

The characteristics and responses of soil bacterial communities and potato productivity to different fertilization treatments in farmlands in the agropastoral zone of Inner Mongolia were investigated. Moreover, the diversity and structure of soil bacterial communities and potato productivity under different fertilization treatments (no fertilization, CK; phosphorus-deficient treatment, NK; conventional fertilization, NPK; and organic–inorganic combination, NPKM) were assessed using Illumina high-throughput sequencing. The results revealed that soil pH, organic matter (SOM), total nitrogen (TN), and total phosphorus (TP) content, and potato productivity were significantly increased under fertilizer treatments (NK, NPK, and NPKM) compared with those under CK, with NPKM treatment having the best enhancement effect. The application of organic fertilizers significantly increased the Shannon, evenness, Chao1, and Ace indices of soil bacterial communities and reshaped the bacterial community structure. Random forest model analysis revealed that soil pH and TP significantly affected soil bacterial diversity, whereas soil pH, SOM, TP, and TN significantly affected soil bacterial community structure. Correlation and structural equation modeling analyses revealed that soil TP and SOM indirectly affected potato productivity by changing soil bacterial diversity and community composition. The results of this study provide a scientific basis for improving the quality and productivity of farmland soil to guide the rational fertilization of farmlands in the agropastoral zone of northern China.