Soil Bacterial Communities Under Different Long-Term Fertilization Regimes in Three Locations Across the Black Soil Region of Northeast China

Although soil bacteria play critical roles in agro-ecosystems, the knowledge of their response to long-term fertilization across the black soil region of Northeast China is limited. In this study, we sequenced 16S rRNA genes to assess the effects of four long-term fertilization regimes—non-fertilization (NoF), chemical fertilizer (CF), manure (M), and chemical fertilizer plus manure (CFM)—on soil properties and bacterial communities in three locations, the northern, middle, and southern parts, across the black soil region. Results showed that the influence of fertilization regimes on soil properties varied significantly among the three locations. Manure fertilization significantly increased microbial biomass carbon and relative abundance of copiotrophic bacteria. Principal component analysis (PCA) showed that the total bacterial communities were separated into three groups according to the sampling location despite long-term fertilization, and that soil pH was the most important factor in shifting bacterial communities. In addition, similar fertilization regimes resulted in different influences on bacterial community composition, and the most influential soil properties varied among the three locations. Our results highlighted that geographical separation was a more dominant factor affecting bacterial communities than fertilization, and that long-term similar fertilization regimes did not induce consistent changes in bacterial community composition in the black soil region.