The use of chemical fertilizer along with organic fertilizer is an important agricultural practice that improves crop yield but also affects soil biogeochemical cycles. In this study, a maize field experiment was conducted to investigate the effects of NPK fertilizer (NPK), organic fertilizer (OF), and their combination (NPK+OF) on soil chemical properties, bacterial and fungal community structures, and diversity compared the control (CK, without any fertilizer). The results showed that the application of OF and NPK-combined OF increased soil organic matter (OM), total N, total P, available N, available P, and available K levels. For alpha diversity analyses, the application of fertilizers led to decreases in soil bacterial and fungal Shannon indices (except for NPK in fungi). Compared with CK, NPK, OF, and NPK+OF fertilization treatments significantly increased the abundances of Acidobacteriota, Gemmatimonadota, and Basidiomycota. Network analysis showed that fertilization produced fewer connections among microbial taxa, especially in the combination of NPK and OF. A redundancy analysis combined with Mantel test further found that the soil OM, available N and P were the main soil-fertility factors driving microbial community variations. Therefore, using organic fertilizer or biological fertilizer combined with chemical fertilizer to improve the status of soil C, N, and P is a promising method to maintain the balance of soil microorganisms in maize field.

Purpose: Substituting chemical fertilizer with organic fertilizer is an important agricultural practice that improves crop yield but also affects soil biogeochemical cycles. Methods: In this study, a corn field experiment was conducted to investigate the effects of NPK fertilizer (NPK), organic fertilizer (OF) or their combination (NPK+OF) on soil chemical properties, bacterial and fungal community structures and diversity using high-throughput sequencing technology. Result: Results showed the application of organic fertilizer and NPK combined organic fertilizer increased OM, TN, TP, AN, AP and AK level. Combined with α-diversity analysis, the application of fertilizers led to a decrease in soil bacterial and fungal diversity. Compared with CK, NPK, OF or NPK+OF significantly increased abundance of dominant bacteria (Acidobacteriota, and Gemmatimonadota) and fungi(Basidiomycota). Bacterial and fungal community composition and structure were different among all four treatments. Network analysis showed that fertilization produced fewer connections among bacterial and fungal taxa in the microbial community, especially in the combination of NPK and organic fertilizer. Redundancy analysis combined with Mantel test further found that soil organic matter (OM) and available N and P were main environmental factors driving microbial community variation. Conclusion: Therefore, using organic fertilizer or biological fertilizer combined with chemical fertilizer to improve the status of soil AN, AP and SOC is a promising method to maintain the balance of soil microorganism in continuous cropping single cropping cotton field.