The latest research shows that plants do not only rely on their roots to obtain nutrients from the soil. They can also directly "eat" atmospheric dust that falls on their leaves, absorbing key minerals such as iron, phosphorus, and potassium, providing a previously underestimated nutrient channel for ecosystems with poor nutrition and strong dust deposition. The relevant paper was published in the botanical journal "New Phytologist" in April this year.
It is estimated that billions of tons of dust are blown up by the wind every year, transported long distances across continents and oceans, and deposited on the surface. This process has long been recognized to play an important role in soil formation and the input of macro- and micronutrients. Because dust particles are rich in phosphorus, iron, potassium and other minerals, scientists have long suspected that the dust itself may be an important source of nutrients for plants.
New research confirms that some plants can absorb these key minerals directly from falling dust through their leaves, a mechanism known as "foliar uptake." The research team pointed out that this path is often ignored in traditional terrestrial nutrient cycle research, but in areas where nutrients are scarce but affected by sandstorms and mineral dust all year round, it may occupy an important position in plant nutrient supply.
“Nature is constantly challenging us with new mechanisms emerging from systems we thought we were familiar with,” Marcelo Sternberg, a plant biologist at Tel Aviv University in Israel, told Refractor via email. "This study shows that plants' nutrient acquisition is not limited to their roots, but they can also absorb nutrients directly from dust through their leaves."
To verify this terrestrial nutrient channel, a research team led by Anton Loksin of Tel Aviv University conducted field experiments in a Mediterranean scrub in the Judean Mountains of Israel, an area known for receiving large amounts of mineral dust from the Arabian and Sahara deserts every year. The researchers spread volcanic ash directly onto the leaves of three common shrubs: Cistus creticus, Salvia fruticosa, and Teucrium capitatum.
The volcanic dust selected for the experiment has a unique "fingerprint" of rare earth elements, which is completely different from the elemental composition of the local soil. This allows the team to distinguish in subsequent analysis which elements are absorbed through the leaves rather than entering the plant from the soil through the roots. The measurement results of elemental content in plants showed that the concentrations of trace elements such as iron, manganese, nickel and copper in the above-ground parts (branches and new tissues) of plants treated with volcanic dust increased significantly, while the concentrations of corresponding elements in the roots remained basically unchanged.
This means that the dust attached to the surface of the leaves is not just washed by rain and then entered into the soil and then absorbed by the roots, but can be directly "digested" by the leaves, providing instant micronutrient supplements to the plants. The research team further combined field observation data with dust deposition and nutrient flux estimates in different regions to assess the potential contribution of leaf dust absorption at larger scales.
The results show that in the western United States, leaf absorption of iron from dust can satisfy up to about 17% of the total iron that local plants obtain from the soil each year; while in the East Amazon, the phosphorus obtained through this mechanism can account for up to about 12% of the plant's annual soil phosphorus input. Although this ratio is not enough to replace the dominant position of root absorption, it is enough to show that dust plays a non-negligible role in the plant nutrient budget in some areas.
Sternberg said that what personally surprised him the most was that the frequent dust storms in the Eastern Mediterranean were not only geological or atmospheric phenomena, but also nutrient supply events with direct biological significance to plants. "We tend to think of dust storms as environmental stress or air quality issues, but for some plants, they can also be a 'fertilizing rain' falling from the sky," he added.
The research also revealed how dust is converted into usable nutrients on the surface of leaves: When dust in the air falls on leaves, organic acids are secreted from the leaves, making the microenvironment slightly acidic, thereby dissolving minerals that would otherwise be difficult to use. This thin acidic "film" helps break down the chemical structure of mineral particles, releasing elements such as iron and phosphorus into forms that can be absorbed by plants.
Sternberg pointed out that some plants have leaf fuzz structures called "trichomes", which are traditionally thought to help lower leaf surface temperatures, increase albedo, and reduce water loss. "This study reveals a previously overlooked function: these leaf hairs can also effectively capture dust particles in the air, thereby enhancing the leaf surface's ability to directly absorb dust nutrients," he said.
The research team believes that as global sandstorm events become more frequent in some areas, understanding the role of dust in plant nutrient cycling has practical significance for agricultural management, ecological restoration, and predicting the ability of ecosystems to cope with climate change. From crop breeding to cultivation management, comprehensive consideration of leaf absorption, soil fertilization, atmospheric deposition and other factors may help humans design more efficient and sustainable nutrient management strategies.
This fact-checked study, jointly completed by multiple scientists, has been officially published in New Phytologist. The relevant results are also attracting continued attention in the fields of ecology and agricultural science.