Short‐Term Impacts of Nitrogen and Nitrogen‐Biofertilizer Amendments on Soil Fungal Communities in Sugarcane Monocropping Systems

Soil fungal communities are essential for nutrient cycling, yet their responses to various soil amendments that combine chemical and biological components in agricultural systems remain underexplored. This study evaluated the effect of synthetic nitrogen (N) fertilizer urea alone (CF: 150 kg ha−1) and in combinations with different biofertilizers (BF) rates, that is, BF1: BF 1000 kg + urea 150 kg, BF2: BF 1500 kg + urea 150 kg, BF3: BF 1000 kg + urea 100 kg, and BF4: BF 1500 kg + urea 100 kg (all rates per hectares) on sugarcane morphology and rhizosphere fungal communities. Results showed that all biofertilizer treatments significantly (p < 0.05) enhanced sugarcane morphology, with BF2 showing the greatest enhancement in stem diameter (1.5‐fold), leaf biomass (3.91‐fold), cane biomass (3.07‐fold), and root‐to‐shoot ratio (> 3‐fold) compared to the control (no fertilizers). Amplicon sequencing revealed 328 shared operational taxonomic units (OTUs), with BF4 having the most unique OTUs (175). Alpha diversity analysis revealed that BF3 had the highest fungal diversity, while BF1 showed the highest richness. Ascomycota was the dominant phylum across treatments, while BF4 increased the relative abundance of Glomeromycota by 2.3‐fold and reduced Fusarium by 2‐fold compared to control. BF4 also enriched taxa such as Agaricomycetes and Trichoderma, and strengthened the correlation between fungal communities and ammonium levels. Soil total N was strongly associated with fungal community composition, suggesting that biofertilizers foster key fungal taxa essential for nutrient cycling. These findings highlight the potential of integrating biofertilizers with reduced urea input to enhance soil microbial health and support sustainable agriculture.