Environmental Sustainability of Nanobubble Watering Through Life-Cycle Evidence and Eco-Innovation for Circular Farming Systems

Nanobubble-saturated water (NBSW) is widely seen as a potential innovation for sustainable agriculture; however, its overall environmental impact still requires clarification. This study examined the sustainability performance of NBSW using laboratory experiments, a life-cycle assessment (LCA), and an expert-based feasibility evaluation. Air and oxygen nanobubble (ONB) watering were applied to silty clay loam and sandy loam soils, and environmental impacts were assessed using ILCD 2011 midpoint indicators. The results revealed that the electricity required for NB generation was the most significant contributor to the impacts across all categories, while material and nutrient inputs had only a minor impact. Air-NB and ONB treatments demonstrated similar life-cycle profiles because of their comparable energy demand. Conventional watering did not involve electricity use but increased nitrate leaching in sandy soil, leading to the possibility of eutrophication. Expert assessments indicated that future adoption of NBSW depends mainly on reducing energy consumption and improving operational reliability and cost efficiency. When combined with low-carbon energy and efficiency improvements, NBSW may contribute to reducing nutrient losses and enhancing resource efficiency in watering. These findings show that NB technology has potential as an eco-innovation, but more study is needed before it can be considered a viable circular-agriculture solution.