Intelligent nano-fertilizers herald the futureFor generations, farmers have understood the importance of nitrogen to the growth of their crops and have struggled to boost nitrogen levels in the soil. Conventional fertilizer can only do this to a small extent, since the bulk of it is destroyed by water or wind before being used by plants.
“For every $100 a farmer puts into the ground, only $30 gets used by the crop—the rest is lost,” explains Dr. Carlos Monreal, a research scientist with Agriculture and Agri-food Canada and an adjunct professor at Carleton University.
But a new technology being developed by Monreal and his colleagues at the University of Alberta and Carleton University could solve this perennial problem.
“We’re trying to develop a new generation of fertilizers that will increase this efficiency from 30 per cent to upwards of 80 per cent,” he says. “The idea is to develop a product that will release nitrogen only when the plant needs it and in the amount the plant needs.”
The key to this is nanotechnology. Monreal is developing a fertilizer made of nano-sized nitrogen molecules coated in a polymer coating that protects the fertilizer from the elements. This coating contains nano-sized “biosensors”—made up of a very specific chemical compound—that allow the fertilizer to be released into the soil when the plant needs it.
These biosensors know when to release nitrogen because they’re able to detect chemical signals being transmitted from the roots of the plant to the soil.
“It’s like a chemical signal that the plant uses to communicate with its surroundings,” says Monreal.
A plant losing water or nutrients to weeds might send out chemicals to harm its competitor, for instance. In some cases, a plant under attack by insects or soil pathogens triggers defence mechanisms that synthesize alkaloids or antibiotics emitted into the surrounding soil to defend itself. Monreal explains that, at certain points in a plant’s lifecycle, its roots send out signals that ask microbes to transform nitrogen in the soil into a chemical form the plant can use.
By eavesdropping on this chemical “conversation,” these biosensors can detect when a plant requires more nitrogen and allow microbes access to the fertilizer-nitrogen inside the polymer-protected particle.
Each plant species sends out its own variety of chemical signals, which means an intelligent nano-fertilizer product could be tailored to respond differently to the needs of different crops. So far, Monreal and his team have explored how this kind of fertilizer might work for wheat and canola, but they’d like to study barley, as well.
Much of the work has focused on the biochemical and molecular questions at the heart of this puzzle, but Monreal stresses that there’s an important industrial component, too.
“Part of the research is to develop the mechanical tools, the engineering, to be able to make the 3-D polymer coating less than 100 nanometres thick,” he says, adding that the coating must also be biodegradable to prevent any environmental impacts. To that end, the research team is collaborating with fertilizer company Agrium and nanotechnology firm NanoGrande.
But as high-tech as the research is, it still stems from basic science and an understanding of natural processes.
“Nature is complex, but very wise,” says Monreal.