Improved organics, from the ground up

September 29, 2009
Written by Andra Zommers
The demand for organic products in Canada has doubled every four years over the last two decades. But Canada’s low productive capacity for organics has left 80 per cent of the market open to imports. Domestic supply has not kept up with consumer demand.

However, new research at the University of Guelph is working to reconcile the organic and local food movements, and put more locally grown organics on Canada’s grocery shelves.

Prof. Youbin Zheng, Department of Environmental Biology, and his team of researchers are investigating sustainable ways to enhance Canada’s capacity to produce locally grown organic produce. They’re developing a greenhouse production system, which will include new organic growing substrates, and determining optimum fertilization, biocontrol and irrigation regimens for producing organic greenhouse vegetables.

 Prof. Youbin Zheng
Prof. Youbin Zheng (front), with project collaborators (from left) Victoria Surrage, Donny Cayanan and Claudia Lafreniere.

The team’s findings will help create a set of protocols that will offer Canadian growers research-based guidelines for organic production.

“Canada is at the top of the world in terms of greenhouse production technology, because we have such a harsh environment,” says Zheng, “but previous efforts with growing substrates have not been that successful. There wasn’t enough research to provide growers with information to get uniform and consistent organic growing substrates.”

Starting from the ground up, post-doctoral research fellow Victoria Surrage is working with Zheng to design new substrates from waste materials. Unlike the conventional greenhouse substrate, rockwool (made from heated rock spun into fibrous slabs), her new substrates use ingredients such as composted manure, vermicompost (worm castings), aged bark, coconut coir, perlite and vermiculite.

These substrates will be used in the greenhouse to provide support for growing plants and to balance their rootzone oxygen and water availability. Their organic composition will also help to provide nutrients to the plants. And, unlike rockwool, which is a non-recyclable material, these new soilless growing substrates will be biodegradable.

But biodegradable substrates can still benefit from fertilizers, a greenhouse staple.

Master’s degree student Claudia Lafreniere is working with Zheng to determine the benefits of what’s called “compost tea” for organic systems. This tea is made by steeping small amounts of compost in large quantities of aerated water until saturated with beneficial fungi and bacteria and poured onto plant roots and leaves. Compost tea may help reduce fertilizer inputs by increasing nutrient cycling in the root zone compared to direct application.

Lafreniere is also investigating ways to control pathogens in greenhouse tomato transplants, which can ruin entire crops, with beneficial micro-organisms. These biocontrols, such as the fungus Clonostachys rosea (a naturally occurring inoculant, also known as EndoFine®), offer growers a natural method for protecting their crops against harmful pathogens without using pesticides.

“It’s like a competition,” says Lafreniere. “If you colonize crops with microbes that aren’t going to hurt the plants, then the microbes that do hurt the plants can’t come in and take over.”

The research team is also developing a fertigation regimen for greenhouse tomato production using new wireless root-zone sensors engineered by master’s student and researcher, Donny Cayanan. The wireless sensors are designed to measure electrical conductivity, volumetric water content and root zone temperature.

“We’re trying to determine which irrigation or fertigation regimen is the most optimum to support plant growth and maximize crop yield,” says Cayanan.

Ultimately, the researchers hope their findings will help create protocols for organic farmers that promote a more efficient, profitable and sustainable organic greenhouse industry in Canada.

Other project collaborators include University of Guelph Profs. Mike Dixon and John Sutton, Department of Environmental Biology, research technician Linping Wang and student Matt Hannaberg, as well as Lindsay Arthur and Amanda Culverwell from the Ontario Ministry of Agriculture, Food and Rural Affairs.

Funding for this research has been provided by the Ontario Ministry of Agriculture, Food and Rural Affairs and the Ontario Centres of Excellence. Additional support has been provided by Forterra Environmental Corporation, Gro-Bark Ltd., Bluewater Produce Ltd., Dingo Farms, Adjuvants Plus Inc. and Biofert Manufacturing Inc.

Andra Zommers is a student writer with the SPARK (Students Promoting Awareness of Research Knowledge) program at the University of Guelph.

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