Every year, billions of tons of dust are lifted into the air and dispersed by winds across continents and oceans. This dust deposition has long been recognized as an important process that contributes to soil formation and delivers essential macro and micronutrients to soils.
Since dust particles are rich in minerals such as phosphorus, iron, and potassium, scientists have wondered whether dust serves as an important source of nutrition for plants.
A new study, published in New Phytologist in April, shows that some plants can enrich themselves by absorbing the essential minerals from dust through their leaves. While this mechanism of nutrient absorption (known as foliar uptake) is well-known, the study highlights an underexplored terrestrial nourishment pathway that plays a major role in plant nutrition in nutrient-poor and dust-affected ecosystems.
“Nature continues to surprise us by revealing new mechanisms, even in systems we think we already understand well,” Marcelo Sternberg, a plant biologist at Tel Aviv University in Israel, tells Refractor, in an email. The study shows that “plants are not limited to taking up nutrients through their roots – they can also absorb nutrients directly from dust through their leaves.”
To explore this terrestrial uptake pathway, Anton Lokshin at Tel Aviv University and his colleagues conducted a field experiment in a Mediterranean shrubland in Israel’s Judean Hills, a region known for its high annual deposits of mineral dust from the Arabian and Sahara deserts.
Here, the team applied volcanic dust directly to the foliage of three common shrub species: Cistus creticus, Salvia fruticosa, and Teucrium capitatum. The volcanic dust contains a signature of rare earth elements that’s unlike the local soil, allowing researchers to show that nutrients were being absorbed through the leaves and not the roots.
They found increased concentrations of micronutrients such as iron, manganese, nickel, and copper in the shoots of the plants dusted with volcanic ash. Meanwhile, the concentrations in their roots remained largely unchanged.
By integrating field observations with dust deposition and nutrient estimates from different regions, the team found that foliar dust uptake could supply up to 17% of the iron that plants in the Western United States receive from soil annually, and up to 12% of the phosphorus in the Eastern Amazon.
“The aspect that surprised me most personally was the realization that dust storms in eastern Mediterranean ecosystems are not only a geological or atmospheric phenomenon, but also a direct and biologically meaningful nutrient pathway for plants,” says Sternberg.
When airborne dust settles on the leaves, the leaf surface creates a slightly acidic environment by secreting nutrient-solubilizing organic acids. A thin layer of acids helps dissolve minerals that otherwise remain unavailable.
Sternberg told us that some plants have hairy leaves called trichomes – an adaptation for reducing leaf temperature, increasing albedo, and limiting water loss. “This study reveals a previously overlooked function: these leaf hairs can also trap dust particles and thereby enhance direct foliar uptake of nutrients from dust,” he concludes.
The study has been published in New Phytologist.
Fact-checked by Mike McRae
