Canadian scientist searches for key to breeding nitrogen-fixing crops

Monday, November 4, 2013

by MATT MCINTOSH

New discoveries about legume genes suggest crops like corn and wheat can be engineered to fix nitrogen says an Agriculture and Agri-Food Canada researcher.

This means farmers may, one day, be able to save money by using less nitrogen fertilizer.

Nitrogen is a key component of healthy soils, and can be added by applying manure, industrially produced fertilizers, or by planting nitrogen-fixing crops, such as legumes like soybeans.

“What we were initially looking for, and what was found several years ago by French scientists, was a kind of missing link,” says Krzysztof Szczyglowski, a molecular geneticist at the Southern Crop Protection and Food Research Center in London, Ontario. “That is, what is genetically different about crops that can and can’t fix nitrogen?”

According to Szczyglowski, the genes that enable legumes to form a relationship with nitrogen-fixing bacteria also allow them to bond with phosphorus gathering fungi, a process most plants can do.  

Through collaborative efforts with groups in Germany and Denmark, Szczyglowski and others at Agriculture and Agri-Food Canada have identified legume genes that are jointly responsible for phosphorus and nitrogen absorption.

Now, they are trying to better understand how those genes work. The breakthrough many scientists are waiting for, says Szczyglowski, is to figure out how legumes have tweaked those genes to communicate with nitrogen-fixing bacteria as well as phosphorus gathering fungi.

“If we can figure out how those genes evolved, we should be able to breed other crops for nitrogen fixation as well," he says.

Szczyglowski says no one knows at what point this will become a reality, but stresses that he believes it will happen "in our lifetime."

He says the financial and environmental costs associated with the industrially produced nitrogen fertilizer commonly used to grow commodity crops like corn and wheat are huge.

He notes the Haber-Bosch process used to generate nitrogen fertilizer such as anhydrous ammonia consumes about half of all the fossil fuels used in agriculture.

The Haber-Bosch process creates ammonia by combining air-born nitrogen and hydrogen derived from natural gas.

For farmers, the fertilizer can be expensive. However, a University of Guelph Oct. 2, 2013 farm input price report notes that fertilizer prices have dropped on average eight per cent compared to the same time last year.

The report says anhydrous ammonia averaged $1,157 per tonne over the last growing season.

Jamie Nash, operator of Setterington’s Fertilizer Service Ltd. near Leamington in Essex County, estimates that the cost of anhydrous ammonia this past growing season was about $70 to $75 per acre “or somewhere around $1,800 for 24 acres” at an average application rate of 140 lbs of actual nitrogen per acre. BF