Money Doesn’t Grow on Trees, but Nickels Do

     The agriculture industry is now harvesting more than just food. Some plants can harvest metal, such as nickel, through a phenomenon known as phytomining. In a recent article from The New York Times, Ian Morse examines this agricultural phenomenon. The sap of these phytomining plants can be sliced open or put through a peanut press to harvest the one-quarter nickel sap. This nickel-producing sap is more concentrated than the 1.2% nickel ore produced from smelting.

     Plants phytomine by collecting minerals from the soil and storing them at high levels, known as hyperaccumulation. There are approximately 700 known plants that thrive in metal-rich soil, at least 65 of which can phytomine nickel. These plants have adapted to their metal-rich environments and they are thought to use the nickel to control pests or more easily gather potassium from the soil.

Fig 1: Testing paper turning a reddish color, indicating high nickel content.

     Dr. Alan Baker from the University of Melbourne has researched the relationship between plants and soil since the 1970s. To prove the efficiency of phytomining as a source of metal, he rented a small plot of land in Malaysia. Every six to twelve months, farmers harvested 1 foot of the plant growth and squeezed or burned the metal-containing sap out of the plants. The sap was then purified and collected. This small plot produced about 500 pounds of nickel citrate, worth thousands of dollars. Nickel is a crucial component used in stainless steel, batteries for electric vehicles, and renewable energies.

     Baker and his colleagues are now scaling up to a 50 acre plot of land with the hopes of combating the mining industry. Mining industries have become increasingly controversial in the age of eco-friendly alternatives, but consumers are not slowing down their energy usage or the demand for these materials. Baker hopes that, in a decade, the demand for base metals and bare minerals can be sustained in part by phytomining. He acknowledges that phytomining might not be able to completely replace traditional mining, but it has many benefits. These plants grow in soils that are toxic to other plants, which allows more land to be productively used. Farmers on land with toxic soil would be able to make use of that soil with phytomining plants to create a new source of income.

     Dr. Baker is hoping this source of income can also sway nickel mining companies. Nickel mining requires coal and diesel fuels and creates acidic waste, toxic soil, and polluted waterways. These phytomining plants partially replace mines and, if planted in abandoned mines, can eradicate the negative byproducts of mining by cleaning up the soil. The revenue from these plants can be used as an incentive, along with the environmental cleanup aspect, to convince companies to consider the rehabilitation of mines through phytomining plants.

     While some people may be scared of metals and toxins that their soil might contain, Dr. Baker is refuting chemophobia by encouraging these communities to clean up their soil and make money doing it. Dr. Baker says that farmers can harvest phytomining plants on soil that contains 0.1% nickel for over 20 years. After two decades, this once-toxic soil will be devoid of nickel, but it can then be used as fertile land for traditional agricultural crops. Other opponents of phytomining have voiced concerns over a possible deforestation in order to plant the hyperaccumulating plants. These fears are unfounded because hyperaccumulating plants only grow in grassy areas that are toxic to most other plants, not in areas that could be deforested. Dr. Baker says that phytomining is “a way of putting back, rather than taking away.”