Hyper-accumulating plants thrive in metallic soil that kills other vegetation, and botanists are testing the potential of phytomining.
Some of Earth’s plants have fallen in love with metal. With roots that act practically like magnets, these organisms — about 700 are known — flourish in metal-rich soils that make hundreds of thousands of other plant species flee or die.
Slicing open one of these trees or running the leaves of its bush cousin through a peanut press produces a sap that oozes a neon blue-green. This “juice” is actually one-quarter nickel, far more concentrated than the ore feeding the world’s nickel smelters.
The plants not only collect the soil’s minerals into their bodies but seem to hoard them to “ridiculous” levels, said Alan Baker, a visiting botany professor at the University of Melbourne who has researched the relationship between plants and their soils since the 1970s. This vegetation could be the world’s most efficient, solar-powered mineral smelters. What if, as a partial substitute to traditional, energy-intensive and environmentally costly mining and smelting, the world harvested nickel plants?
Dr. Baker and an international team of colleagues has set its sights on convincing the world the idea is more than just a fun thought experiment. On a plot of land rented from a rural village on the Malaysian side of the island of Borneo, the group has proved it at small scale. Every six to 12 months, a farmer shaves off one foot of growth from these nickel-hyper-accumulating plants and either burns or squeezes the metal out. After a short purification, farmers could hold in their hands roughly 500 pounds of nickel citrate, potentially worth thousands of dollars on international markets.