The development of nano-fertilizers, especially nano-urea, has created opportunities to improve agricultural nutrient use efficiency and possibly reduce environmental losses. Beyond its agronomic advantages, however, little is known about the ecological effects of nano-urea on soil biotic communities. The function of nano-urea as a modulator of soil biotic interactions is examined in this review, with an emphasis on how it affects cropping systems’ macrofaunal functionality and soil microbiota diversity. The distinct physicochemical characteristics of nano-urea, including its high surface area, controlled release behaviour, and nanoscale mobility, can impact enzymatic activity, nitrogen-transforming populations, and microbial community dynamics, which in turn can impact soil health and nutrient cycling. At the same time, interactions with soil macrofauna, such as nematodes, arthropods, and earthworms, present opportunities and challenges for trophic interactions, organic matter turnover, and soil structure maintenance. According to new research, depending on dosage, application technique, and environmental conditions, nano-urea may have both beneficial and detrimental effects on these biotic groups. Crucially, the intricate ecological footprint of nano-urea is highlighted by the cascading effects between micro- and macro-biota, such as shifts in microbial availability impacting macrofaunal feeding and activity. This review summarises recent research, points out important knowledge gaps, and suggests an integrative framework for assessing how nano-urea shapes biotic interactions in agroecosystems. The necessity of interdisciplinary research is emphasised in order to ensure the sustainable integration of nanotechnology in contemporary agriculture by striking a balance between ecological integrity and productivity gains.
