In the sun-drenched plastic tunnels of Almería, where Europe’s winter vegetables are grown under a relentless Mediterranean sky, a quiet revolution is unfolding—not in the crops themselves, but in the water that feeds them. A team led by soil scientist Francisco del Moral, from the University of Almería’s Department of Agronomy, has just published field evidence that could change how growers, engineers, and energy providers think about irrigation in intensive greenhouse systems.
The study, published in *Agricultural Water Management* (*Gestión del Agua Agrícola*), tracked how micro- and nanobubble (MNB) fertigation affects the behavior of trace elements like arsenic, copper, chromium, cadmium, and lead in soils used for tomato cultivation. “We’re not just measuring yields,” says del Moral. “We’re looking at the invisible chemistry happening beneath the surface—how oxygen-rich bubbles can shift where metals go, and how that might help us farm more safely and sustainably.”
Over 150 irrigation events, the researchers compared three scenarios: air-based nanobubbles (MNBA), oxygen-based nanobubbles (MNBO), and a conventional control. What they found was a clear divergence in trace element fate. MNBO, with its higher dissolved oxygen (24.2 mg/L), increased the bioavailability of several metals—raising concerns for both food safety and downstream environmental impact. “Oxygen nanobubbles can make metals more mobile,” explains del Moral. “That might help nutrient uptake, but it also risks mobilizing contaminants.”
In contrast, air nanobubbles—delivering 7.0 mg/L oxygen—produced a stabilizing effect. Soluble organic carbon dropped, and metals like arsenic and cadmium were more tightly bound to iron and manganese oxides, while lead shifted into organic-bound forms. “It’s like giving the soil a gentle nudge toward safer chemistry,” he notes. “We saw less water-soluble copper and more stable lead—important for long-term soil health.”
For the energy sector, the implications are significant. Greenhouse operations in Almería consume vast amounts of electricity to pump, filter, and oxygenate irrigation water. Nanobubble technology—especially oxygen-enriched variants—could reduce energy demand by improving oxygen transfer efficiency compared to conventional aeration. “If we can deliver the same—or better—oxygenation with fewer kilowatt-hours, that’s a direct win for energy intensity,” del Moral says.
The findings also point to a new dimension in precision agriculture: using nanobubbles not just to feed plants, but to steer soil chemistry. By tuning bubble composition and dosage, growers might one day optimize nutrient cycling while minimizing metal risks—a balance critical for high-value export crops like tomatoes.
As greenhouse horticulture expands globally, driven by climate change and resource scarcity, technologies that enhance water use efficiency and soil stability will be essential. The Almería study offers a glimpse of how fine-tuning the very air in water could become part of that toolkit.
“This isn’t just about cleaner soil,” says del Moral. “It’s about smarter irrigation—where every bubble counts.”