Impacts of Fertilizers with Varying Nitrogen Contents on Millet Yield and Rhizosphere Soil Microbial Communities: Implications for Sustainable Agricultural Development

Nitrogen (N) is a vital macronutrient affecting crop productivity, yet the influence of different N contents in fertilizers on rhizosphere soil microbial diversity is not well understood. This study used high-throughput 16S rRNA and fungal ITS sequencing to examine the impact of varying N contents (low (LN, 90 kg/ha), medium (MN, 120 kg/ha), and high (HN, 150 kg/ha)) on root-associated microbial communities. The results revealed that Millet yield increased with N level: HN (7.14 Kg/ha) > MN (6.33 Kg/ha) > LN (5.62 Kg/ha), with HN yields significantly higher than LN (p < 0.05). No significant differences in microbial α-diversity were noted among three groups. Gemmatimonadota, Acidobacteriota, and Ascomycota were the dominant phyla, whereas Sphingomonas, Vicinamibacteraceae, and Fusarium were the predominant genera. LEfSe analysis showed that Entotheonellaeota were substantially enriched in the LN group at the phylum level. At the genus level, there was marked enrichment of Rhodothermaceae: Fusicolla were in the LN group and PLTA13, Luteimonas, and Edaphobaculum were in the MN group, whereas Aridibacter and Parviterribacte were enriched in the HN group. Fertilizers with varying N contents affected rhizosphere soil microbial community composition and millet yield. These findings provide valuable insights for developing scientifically-based fertilization strategies to promote sustainable agricultural ecosystems.