Sunlight-Bottling Bionic Leaf Can Create Fertilizer And Boost Food Supply


Described as something that can drive the next green revolution, a leafy invention by Harvard University is able to produce fertilizer on-site, without the need for expensive industrial machinery.

The artificial leaf captures sunlight and uses this energy to create fertilizer in its own body. When released into the soil, the bioengineered fertilizer is potent enough to make surrounding plants grow 1.5 times bigger than normal.

The innovation, presented at the annual meeting of the American Chemical Society in San Francisco, continues Harvard's previous work that resulted in a device mimicking natural leaves to split water into hydrogen and oxygen.

Making Fertilizer From Scratch

As Science Magazine explains, one of the key components of fertilizer is nitrogen. This element is available all around us in nature, but can only be accessed by certain bacteria, which have evolved special proteins to split nitrogen molecules from the air and fuse them with hydrogen in order to produce ammonia.

It's the ammonia in the soil that acts as fertilizer, enabling plants to absorb nitrogen and grow.

To develop their bionic leaf, researchers turned to these bacteria, called Xanthobacter autotrophicus, which they genetically engineered to harness hydrogen and combine it with carbon dioxide to create a type of bio-plastic.

Xanthobacter deposits this bio-plastic internally and uses it as a private hydrogen store, into which it can tap anytime to make ammonia by combining it with the nitrogen the bacterium already produces.

This process resulted in a new type of fertilizer. When tested on the field, the engineered Xanthobacter led to 150 percent larger crops after it had been sprayed in a solution on a plantation of radishes.

Bionic Leaves: From Hydrogen Fuels To Bigger Crops

This is not the first time the Harvard team, led by chemist Daniel Nocera, have used bacteria in their research to create bionic leaves.

In previous experiments, Nocera engineered another type of bacteria, Ralstonia eutropha, to harvest hydrogen and carbon dioxide from the air and produce hydrocarbon fuels.

The study, published last year, was in turn based on Nocera's earlier work. Six years ago, the scientist created a bionic leaf that was able to split water molecules into basic elements using sunlight.

At the time, Nocera focused his research on separating hydrogen from oxygen with the purpose of producing fuel and electricity.

His latest invention employs the same principles to create fertilizer from bio-plastic that internally stores hydrogen.

"We've basically bottled sunlight in the form of this bio-plastic," said Nocera.

Help For Struggling Agricultural Communities

Commercial fertilizer is manufactured following a similar method called the Haber-Bosch process, named after its inventors Fritz Haber and Carl Bosch. Chemical plants convert hydrogen (typically taken from methane) and nitrogen into ammonia.

However, the cost of supporting this technology on an industrial scale and later distributing the product to farmers makes it inaccessible to many impoverished rural areas.

The man-made leaf created by Nocera has the great advantage of producing fertilizer directly in farm soil and could help agricultural communities in developing countries significantly boost their crop yields.

Nocera believes his invention, which has a very low cost in terms of traditional fertilizers, could one day allow poor farmers in sub-Saharan Africa or rural India produce their own fertilizer.

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