44-Years of Fertilization Altered Soil Microbial Community Structure by Changing Soil Physical, Chemical Properties and Enzyme Activity

Soil microorganisms play a crucial role in nutrient cycling, maintaining soil fertility, and carbon sequestration in soil. However, our understanding of the adaptive mechanisms and driving factors of microbial community structure in non-calcareous fluvo-aquic soil under different fertilization treatments remains limited. A field experiment was designed with winter wheat-summer maize rotation system started in 1978. Five treatments were selected: CK (no fertilizers); N (nitrogen); NPK (nitrogen, phosphorus and potassium); M (60,000 kg pig manure ha⁻¹); MN (60,000 kg pig manure + 276 kg N ha⁻¹). The results showed that N, NPK, M and MN treatment significantly increased soil organic carbon (SOC) and total nitrogen (TN) by 22.7% and 38.8%, 23.1% and 30.5%, 113.4% and 141.6%, 167.1% and 304.1% compared to CK, respectively. Long-term fertilization (NPK, M, and MN) alters the structure of soil microbial communities through improvements in soil carbon and nitrogen cycles and soil enzyme activities. Additionally, pig manure application significantly enhanced the relative abundance of Pezizomycetes (35.9%) and Firmicutes (23.4%). Redundancy analysis (RDA) indicated that TN and SOC are the primary factors driving the changes in soil bacterial communities. TN and catalase activity are the main factors driving the changes in the soil fungal community. Overall, long-term fertilization, especially the addition of organic resources, can strengthen the biological regulation processes in soil ecosystems to maintain or enhance soil fertility.