Boston: Scientists have developed a "bionic" leaf that can help farmers produce their own fertilisers and potentially prevent an impending food crisis by boosting crop production in developing countries like India.
To contribute to the next green revolution, researchers are building the artificial leaf to make fertiliser.
The artificial leaf is a device that, when exposed to sunlight, mimics a natural leaf by splitting water into hydrogen and oxygen.
"When you have a large centralised process and a massive infrastructure, you can easily make and deliver fertiliser," said Daniel Nocera, from the Harvard University in the US.
"But if I said that now you've got to do it in a village in India onsite with dirty water - forget it," said Nocera.
"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," he said.
The first "green revolution" in the 1960s saw the increased use of fertiliser on new varieties of rice and wheat, which helped double agricultural production.
Although the transformation resulted in some serious environmental damage, it saved millions of lives, particularly in Asia, according to UN Food and Agriculture Organisation.
However the world's population continues to grow and is expected to swell by more than two billion people by 2050, with much of this growth occurring in some of the poorest countries, according to the UN.
Providing food for everyone will require a multi-pronged approach, but experts agree that one of the tactics will have to involve boosting crop yields to avoid clearing even more land for farming.
The bionic leaf pairs the water-splitting catalyst with the bacteria Ralstonia eutropha, which consumes hydrogen and takes carbon dioxide out of the air to make liquid fuel.
The new system provided biomass and liquid fuel yields that greatly exceeded that from natural photosynthesis.
"We are demonstrating the generality of it by having another type of bacteria take nitrogen out of the atmosphere to make fertiliser," said Nocera.
For this application, Nocera designed a system in which Xanthobacter bacteria fix hydrogen from the artificial leaf 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 said.
"Then the bug pulls nitrogen from the air and uses the bioplastic, which is stored hydrogen, to drive the fixation cycle to make ammonia for fertilising crops," he said.
The researchers used their approach to grow five crop cycles. The vegetables receiving the bionic-leaf-derived fertiliser weighed 150 per cent more than the control crops.
The next step is to boost throughput so that one day, farmers in India or sub-Saharan Africa can produce their own fertiliser, Nocera said.