RT Journal Article T1 Biofertilizers for Enhanced Nitrogen Use Efficiency: Mechanisms, Innovations, and Challenges A1 Herrero, Joaquín A1 Ramírez Santos, Adrián A1 Díaz Santos, Encarnación A1 Torres Cortés, Gloria AB The extensive use of synthetic nitrogen fertilizers has sustained global food production for more than a century but at high environmental and energetic costs. Improving nitrogen use efficiency (NUE) has therefore become a key objective to maintain productivity while reducing the ecological footprint of agriculture. This review synthesizes current knowledge on the biological foundations of NUE enhancement, focusing on the role of microbial biofertilizers and biostimulants. The main mechanisms through which plant-associated microorganisms contribute to nitrogen acquisition and assimilation are analyzed. In parallel, advances in genomics, biotechnology, and formulation science are highlighted as major drivers for the development of next-generation microbial consortia and bio-based products. Particular attention is given to the current landscape of commercial biofertilizers and biostimulants, summarizing the principal nitrogen-fixing and plant growth-promoting products available on the market and their agronomic performance. Moreover, major implementation challenges are discussed, including formulation stability and variability in field results. Overall, this review provides an integrated perspective on how biological innovations, market evolution, and agronomic optimization can jointly contribute to more sustainable nitrogen management and reduce dependence on synthetic fertilizers in modern agriculture. PB MDPI SN 2504-3129 (electrónico) YR 2025 FD 2025 LK https://hdl.handle.net/10272/27697 UL https://hdl.handle.net/10272/27697 LA eng NO Herrero, J., Ramírez-Santos, A., Díaz-Santos, E., & Torres-Cortés, G. (2025). Biofertilizers for Enhanced Nitrogen Use Efficiency: Mechanisms, Innovations, and Challenges. Nitrogen, 6(4), 111. https://doi.org/10.3390/nitrogen6040111 DS Repositorio Institucional de la Universidad de Huelva RD 30 may 2026