Researchers have invented a new bionic leaf that uses bacteria, sunlight, water and air to make fertilizer in the very soil where crops are grown. It is hoped that the leaf will be able to serve a vital role in kickstarting a new ‘green revolution’ like that of the mid-20th century.
The first green revolution saw a massive increase in the use of fertiliser on new wheat and rice varieties, helping to double agricultural production. Though far from a perfect solution – the increased use resulted in serious environmental damage – the United Nations (UN) Food and Agriculture Organization have said that the move quite possibly saved millions of lives.
However, while it served at the time, a new green revolution is required. With the world’s population expected to grow by another 2 billion by 2050, a solution to boost production without having to clear masses more land for farming is urgently required.
A multi-pronged approach will be necessary, but the bionic leaf could play a vital role.
“When you have a large centralised process and a massive infrastructure, you can easily make and deliver fertiliser,” said Dr Daniel Nocera.
“But if I said that now you’ve got to do it in a village in India onsite with dirty water — forget it. Poorer countries in the emerging world don’t always have the resources to do this. We should be thinking of a distributed system because that’s where it’s really needed.”
Nocera is known for his previous work on artificial leaves turning sunlight into liquid fuel, which we reported on here, and is now looking to turn that expertise towards the creation of fertiliser.
Previous iterations of the leaf, when exposed to sunlight, paired a water-splitting catalyst with the bacteria Ralstonia eutropha, which consumes hydrogen and takes carbon dioxide out of the air to make liquid fuel.
Last June, Nocera’s bionic leaf even reached the point of providing biomass and liquid fuel yields that greatly exceeded those from natural photosynthesis. Now, by using Xanthobacter bacteria, the leaf can fix hydrogen from itself and carbon dioxide from the atmosphere to make a bioplastic that the bacteria store inside themselves as fuel.
“I can then put the bug in the soil because it has already used the sunlight to make the bioplastic,” Nocera explained. “Then the bug pulls nitrogen from the air and uses the bioplastic, which is basically stored hydrogen, to drive the fixation cycle to make ammonia for fertilising crops.”
The research team have already tested the ammonia production of the system but have found real proof in growing radishes. Using the system to grow five crop cycles, they found that the vegetables receiving the bionic-leaf-derived fertilizer weigh 150 percent more than the control crops.
With this success behind them, Nocera has said that the next step is boosting throughput to get to the point where farmers in locations such as India or sub-Saharan Africa can produce their own fertiliser.