Fertilizer regimes reshape microbial interaction networks without altering sugarcane rhizosphere diversity

Abstract. Sugarcane (Saccharum spp.), an economically important crop in the food and bioenergy industries, has historically played a central role in the economy of Cuba, shaping its agricultural landscape and international relations. Although production has declined in recent decades, sugarcane remains a strategic crop, with its byproducts contributing to national energy and industrial outputs. However, the way in which long-term fertilization interacts with soil microbial communities under varying edaphoclimatic conditions remains largely unknown. Here, we investigated a traditional sugarcane plantation to evaluate how distinct fertilizer formulations varying in nitrogen, phosphorus, and potassium affect the soil and rhizosphere microbiota. Using high-throughput sequencing of 16S rRNA (bacterial) and internal transcribed spacer (fungal) genes, we identified 421 bacterial and 471 fungal genera from 5,741 amplicon sequence variants across different fertilization regimes. While microbial composition and diversity did not differ significantly between treatments, co-occurrence network analysis showed clear nutrient-specific patterns. This indicated that each fertilizer regime shaped distinct interaction networks among microbial taxa. These shifts suggest modifications in soil and rhizosphere functioning linked to nutrient availability rather than to taxonomic turnover alone. The findings provide a detailed characterization of the rhizosphere microbiome of Saccharum spp. in brown sialitic soils (inceptisol), offering ecological insights into its bacterial–fungal associations. This highlights the importance of understanding how long-term fertilization regimes influence rhizosphere microbial dynamics, which is key to designing more sustainable soil management and fertilization practices in sugarcane production systems.