Healthy Soils, Stronger Harvests: Sustainable Farming in Ontario's Greenbelt - Vineland Research & Innovation Centre

Background

The Greenbelt Foundation Substrate Reuse Project was developed to address a growing sustainability challenge within Ontario’s greenhouse sector: the large volume of greenhouse growing media, including stone wool (rockwool), coco coir, and other substrates, that are typically disposed of in landfill at the end of production cycles. Internal project documents estimate that approximately 30,000 tonnes of greenhouse substrate waste are landfilled annually in Ontario, creating both environmental and economic challenges for growers.

The project aligns with the Greenbelt Foundation Sustainable Greenbelt funding stream, which supports initiatives that strengthen local food systems, improve agricultural resilience, and enhance environmental sustainability within Ontario’s Greenbelt. The research aims to determine whether spent greenhouse substrates can be safely and effectively reused as agricultural soil amendments, thereby supporting a more circular economy while improving soil health and crop production.

Goal

To develop science-based best management practices that enable greenhouse substrate waste to be safely and effectively reused as a soil amendment, transforming a landfill-bound waste stream into a valuable agricultural resource that improves soil health, supports farm productivity, and strengthens the sustainability of Ontario’s Greenbelt agricultural sector.

Objectives

Divert greenhouse substrate waste from landfill by identifying practical reuse pathways for spent greenhouse growing media and reducing disposal costs for growers.
Evaluate spent greenhouse substrates as agricultural soil amendments under field conditions to determine their suitability, effectiveness, and environmental sustainability.
Assess impacts on soil health and resilience, including water-holding capacity, soil physical properties, and other key soil health indicators.
Measure crop performance across two field crop cycles—sweet corn and broccoli—to determine how substrate amendments influence crop establishment, growth, yield, and marketable production under Ontario growing conditions.
Evaluate water quality and environmental outcomes, including nutrient retention, leachate reductions, and improvements in soil-water dynamics.
Develop science-based best management practices for the beneficial reuse of greenhouse substrates in agricultural production systems.
Support a circular agricultural economy by transforming greenhouse waste materials into valuable soil health resources for Ontario farmers.
Facilitate grower adoption through knowledge transfer and demonstration activities, including field trials, demonstration days, extension materials, and outreach events.

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