Partial substitution of chemical fertilizers by organic fertilizers improves inter-root soil microbial community structure and nutrient dynamics 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 investigates how the partial substitution of chemical fertilizers with organic ones affects the structure of inter-root soil microbial communities and their response mechanisms in a typical barrier soil, specifically the Albic Soil found in Heilongjiang Province. Simulated potting experiments and high-throughput sequencing analysis revealed that replacing chemical fertilizers with organic ones significantly improved the physicochemical properties of Albic Soil's inter-root soil, increased microbial diversity, and optimized the microbial community structure. Specifically, 75% level treatment notably elevated the pH value and nutrient content, including OM, TP, HN and AP in the inter-root soil. This also fostered the growth and reproduction of the dominant bacterial species Proteobacteria and the dominant fungi species Basidiomycot. LEfSe analysis revealed that the fungi community was more sensitive to the fertilizer application strategy than the bacterial communities. Furthermore, redundancy analysis (RDA) demonstrated that soil pH and organic matter are the primary environmental factors influencing microbial community structure. The co-occurrence network analysis showed that partial replacement of chemical fertilizers with organic ones strengthened species interrelationships, leading to a more complex and dense bacterial network. This study's findings offer a significant scientific foundation for refining the fertilization strategies for Ablic soil and facilitating the shift from conventional to sustainable agricultural practices.