Effects of Organic Fertilizer Replacement on the Microbial Community Structure in the Rhizosphere Soil of Soybeans in Albic Soil

With the intensification of agricultural production, the significance of soil biological health and microbial network structure has grown increasingly critical. Replacing chemical fertilizers with organic ones has garnered widespread attention as an effective strategy for enhancing soil quality. This study investigated the influences of the partial replacement of chemical fertilizers with composted cow manure on the structure and response mechanism of the microbial community in the rhizosphere soil of soybeans in the Albic soil with barriers. Potting trials and high-throughput sequencing analysis revealed that organic fertiliser substitution enhanced both nutrients and bacterial diversity in the rhizosphere soil of soybeans in Albic soil. Additionally, this substitution promoted a more complex bacterial network structure. Compared with conventional fertilization, the soil ACE and Chao1 diversity indices in the treatment with 75% organic fertilizer substitution significantly increased by 19.49% and 21.02%, respectively. The soil pH, organic matter, total phosphorus (TP), effective phosphorus (AP), and hydrolyzed nitrogen (HN) levels exhibited a marked increase of 4.33%, 18.67%, 20.90%, 23.35% and 32.97% with high levels of organic fertiliser replacement, as compared to NPK. Meanwhile, the dominant phyla of Proteobacteria and Basidiomycota significantly increased by 36.11% and 286.79%, respectively. LEfSe analysis revealed that the fungal community was more sensitive to the fertilizer application strategy than the bacterial communities. Furthermore, redundancy analysis (RDA) demonstrated that soil pH and organic matter were primary environmental factors influencing microbial community structure. The co-occurrence network analysis showed that the partial utilization of organic fertilizers could strengthen the interrelationships among species, leading to a more complex and dense bacterial network. The findings can offer a significant scientific foundation for refining the fertilization strategies for Albic soil and facilitating the shift from conventional to sustainable agricultural practices.