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Researchers tout 'smart' fertilizer - Chemical coating 'reads' the signals from plants and releases nutrients

Posted by Flaman Agriculture Sep 28, 2015

26 Sep 2015
Ottawa Citizen
TOM SPEARS

 

Researchers tout 'smart' fertilizer

Chemical coating 'reads' the signals from plants and releases nutrients

She never planned to study fertilizers. Maria DeRosa, a chemistry professor raised in Ottawa, dreamed of designing drugs that deliver themselves directly to targets inside the human body.

Maria DeRosa in her lab at Carleton U holds a handful of soil.

A decade later she is proudly showing off the results that came when a colleague persuaded her to take a sharp turn, and to deliver "smart" fertilizers to farm crops instead.

DeRosa, from Carleton University, and Carlos Monreal of Agriculture Canada, have designed a way to make fertilizer release its nutrients when crops need them, and lock them up tight when crops don't need feeding. This prevents fertilizer from washing away unused and polluting lakes and rivers.

And the clue to it all was realizing that plants send out signals into the soil, and that DeRosa and Monreal could eavesdrop on them.

The soil under a wheat or canola field is a complex place.

"The soil has microbes and all sort of things going on that are living there," DeRosa said. For instance, a whole community of tiny fungi and bacteria interact with plant roots to help the plant absorb nutrients.

And when wheat or canola need nitrogen, they release chemicals that appear to be a sort of signal — possibly to the soil microbes, telling them to deliver the plant food.

Monreal says ordinary soil contains millions of organisms — bacteria, viruses, insects, worms, fungi — all interacting in a complex world that we don't yet understand. Some of them help plants absorb nutrients.

"We have the Hubble Telescope and we're all the time looking at the stars and galaxies. We're very good at that," he said. "But we invest so little to study what is under our feet, because it's hidden and we don't think about it."

Still, the signal was a clue to feeding plants when they need it most.

Monreal and DeRosa gave the fertilizer a chemical coating. This is the part that qualifies as a smart fertilizer: Chemicals in the coating, called aptamers, react to the "feed me" signal from wheat and canola, and they make the coating break down. This releases the plant food when the plants need it.

It can be adapted for microscopic fertilizer particles or for much larger ones.

It's estimated that farmers in Canada lose $1 billion a year in fertilizer that never reaches the crops, DeRosa said.

"I didn't even realize (at first) that this was a problem."

Yet when fertilizer washes into a body of water, it stimulates the growth of weeds and algae blooms.

At Agriculture Canada in Ottawa, Monreal is studying the signals that comes from plants, hoping to find out how many kinds there are. There's a lot still to learn.

What about home garden applications?

"Sure, tomatoes! Everyone wants to know," DeRosa said. So far, the research is just on grains, which use fertilizers on a much bigger scale. But she advises that patience will pay off for gardeners eventually.

"The mechanism should be the same."

The technique hasn't been commercialized yet, but the pair have been working with industrial partners along the way, and expect patenting and commercial production will follow.

"At the beginning this was science fiction and now we're starting to say: 'Hey, this could actually work'."

But she is also excited to think that the lessons from a wheat field could lead to drug delivery and more uses of smart chemicals, such as delivering a drug to a cancer cell and not to a healthy cell.

"From a science point of view the applications are so broad."

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