Soil health under drip irrigation: The role of nanobubble-induced soil aeration in biogeochemical processes — A review

Micro- and nanobubble (MNB) technology (MNBT) has been identified as emerging strategy in sustainable farming, specifically in improving soil health, nutrient cycling, and the rhizosphere functionality using drip irrigation systems. MNBs have exceptional physicochemical characteristics (e.g., tiny size and longer residence in aqueous media) that enable efficient delivery of air, oxygen or other gases directly to the plant rhizosphere. This review investigates MNBs role in altering the most important biological, chemical and physical processes, explicitly in the rhizosphere oxygenation, modulation of the microbial community, activation of enzymes and enhancement of carbon and nitrogen cycling. Firstly, the prospects of the MNBs in saline and heavy-metal-contaminated soil remediation through oxidative degradation and redox regulation have been summarized. Secondly, we compiled new evidence on the effects of MNBs on soil aggregation, pH, redox potential, and water retention, along with their potential agro-environmental benefits. Thirdly, to establish a strategic framework of integrating MNBs in synergy with biological soil amendments, precision agriculture, circular water reuse systems, and bioengineered soil solutions, while contributing to the United Nations Sustainable Development Goals (SDGs). Ultimately, the main knowledge gaps were summarized to support up-scaling and low-chemical approaches for restoring soil vitality and sustainable agroecosystems.