Large amounts of metal in soil are generally bad for plants.  But there are about 700 species of plants

that thrive in metal-rich soils.  These

plants don’t just tolerate minerals from soil in their bodies but actually seem

to hoard them to ridiculous levels.

In areas where soils are naturally rich in nickel, typically in the

tropics and Mediterranean basin, plants have either died off or have adapted to

become nickel loving.  Slicing open a

tree with this adaptation produces a neon blue-green sap that is actually

one-quarter nickel, which is far more concentrated than the ore that typically

feeds commercial nickel smelters.

A group of researchers from the University of Melbourne and other

institutions is investigating whether this phenomenon is not just interesting

but might also be of real commercial value. 

They established a plot of land in a rural village in Borneo and have

been harvesting growth from nickel-hyper accumulating plants.  Every six to twelve months, a farmer shaves

off one foot of growth from these plants and either burns or squeezes the metal

out.  After a short purification, they

end up with about 500 pounds of nickel citrate, potentially worth thousands of

dollars on international markets.

Phytomining – extracting minerals from hyper-accumulating plants –

cannot fully replace traditional mining techniques.  But the technology could enable areas with

toxic soils to be made productive and might allow mining companies to use

plants to clean up their former mines and waste while actually collecting some

revenue.

There are other plants that suck up cobalt, zinc, and similarly

crucial metals.  With growing demand for

metals, perhaps it is time to harvest them on the farm.

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Down on the Farm That Harvests Metal From Plants

Photo courtesy of the University of Queensland.

Earth Wise is a production of WAMC Northeast Public Radio.