Short-Term Phosphorus Fertilization Alters Soil Fungal Community in Long-Term Phosphorus-Deprived Yellow Soil Paddy Fields

Phosphorus (P) in soil is important in the process by which soil microbial communities regulate soil enzyme activity. We aim to explore how short-term P fertilization affects the composition and functionality of the soil fungal community, offering insights into the complex responses of soil fungi to fertilization. Soil samples from a long-term experiment with no P fertilization were collected for pot experiments. The pot experiment included four treatments: non-P fertilizer (NK), chemical P fertilizer (NPK), 1/2 organic fertilizer + 1/2 chemical fertilizer (MNP), and organic fertilizer (M). High-throughput sequencing was employed to analyze the composition, diversity, and functionality of soil fungal communities. Results showed that short-term P addition significantly increased the soil fungal Shannon and Pielou e indices, with increases of 34.48%~59.00% and 29.79%~53.19%, respectively. Ascomycota and Basidiomycota were the most abundant fungal phyla, whereas Cladosporium and Emericellopsis were the most abundant genera. The main factors affecting soil fungal community composition were total nitrogen (TN) and organic matter (OM). A linear discriminant analysis effect size (LEfSe) analysis indicated that Mortierellomycota were significantly enriched under the NPK treatment. A FUNGuild analysis revealed that, compared to the NK treatment, the relative abundance of Animal Pathogen–Endophyte–Lichen Parasite–Plant Pathogen–Wood Saprotroph was reduced by 67.54%, 46.93%, and 44.10% under NPK, MNP, and M treatments, respectively. The relative abundance of Plant Pathogen was less than 1% in the NPK and the MNP treatments. These results indicate that short-term P addition increased soil nutrient levels and soil fungal community diversity. Chemical P fertilizer significantly improved the fungal community structure in yellow paddy soils, enhancing beneficial fungi and suppressing pathogens.