"Deactivating ToBRFV results in thousands of tonnes of greenhouse waste diverted from landfills"

Colleagues from Walker Industries (Walker) and the Ontario Greenhouse Vegetable Growers (OGVG) completed their multi-year study evaluating the efficacy of Walker's GORE® composting process in deactivating tomato brown rugose fruit virus (ToBRFV). The study was successful and secured a new disposal method for spent stone wool (i.e., rockwool), vines, and other organic greenhouse waste infected with the virus.

Greenhouse waste such as this stone wool (a soilless media used for cultivation) and vegetable vines are commonly discarded in landfills across Ontario over the concerns of spreading or reintroducing the plant pathogen into tomato greenhouses. However, Walker's results demonstrate that greenhouse waste infected with ToBRFV can be safely composted and diverted from landfills. This could mean more than ~35,000 tonnes (MT) of compostable waste can be recovered and safely reused each year.

"Walker prides itself on being a leader in resource recovery through innovation," said Geoff Boyd, Vice President, Resource Recovery at Walker. "This discovery will take the pressure off the province's waste management infrastructure by inserting thousands of tonnes of recycled compost waste back into the circular economy and out of landfills."

As part of a project that was supported through the Greenhouse Competitive Innovation Initiative (GCII), Walker was able to verify that the ToBRFV was fully deactivated in the stone wool, vines, and greenhouse waste tested. Further, it was concluded that Walker's standard eight-week GORE composting process is all that is required to ensure the safe management and reuse of infected greenhouse waste. This was attributed to the fact that Walker's GORE composting system achieved temperatures of more than 75°C for more than 40 percent of the compost residency time (and remained above 55°C throughout the entire process).

"In Ontario, materials such as stone wool slabs are one of the main substrates used in greenhouse vegetable production but have been thrown into landfills. This study creates an environmentally friendly solution and opens doors to other composting solutions," says Erin Agro, Growing Media Group Manager at Walker.

"I congratulate Walker Industries and the Ontario Greenhouse Vegetable Growers for collaborating to develop this innovative composting project that will benefit the agri-food sector and enhance sustainability over the long term," said Minister of Agriculture, Food and Rural Affairs Lisa Thompson. "I am delighted that this project was made possible through the Greenhouse Competitiveness and Innovation Initiative, a great example of a leading-edge approach that will increase agri-food innovation and adoption." Due to the success of this trial, Walker is continuing to investigate potential beneficial end uses for composted stone wool and is exploring options for end-of-crop-cycle waste collection and processing in the Windsor-Essex area to offer sustainable and safe alternatives to landfilling and incineration.

This project was partially funded by the Greenhouse Competitiveness and Innovation Initiative, a cost-share program funded by the Ontario Government and delivered by the Agricultural Adaptation Council on behalf of the Ontario Ministry of Agriculture, Food and Rural Affairs