Nurturing Soil, Growing Community TogetherCompost Toronto

Building Biological Compost since 2022

Colleen Dempster

12/26/20253 min read

Who we are: Located in the Greater Toronto Area, we are a collective of people who share a common vision and passion for healthy soil and compost. Our core members include experienced composters and vermicomposters, gardeners, laboratory technicians, compost tea/extract application professionals, and more. We are trusteed by the charity Green Thumbs Growing Kids, which teaches composting as part of their school garden programs.
What we do:

Compost Building – biologically focused thermal aerobic, Johnson-Su, vermicomposting and more,
Sharing feedstock, tools, labour and expertise, time monitoring compost piles,
Microscope Workshops,
Gatherings and Educational Events,
Online communications and calls for action through WhatsApp and Email,
Apply compost, teas and extracts,
Experiment, learn and grow together!
Support each other and have fun!

The importance of living soil

Healthy soil contains about a billion bacteria, thousands of protozoa, hundreds of beneficial nematodes, and several yards of fungal hyphae in just 1g (1 teaspoon) of soil. These microbes interact with plant roots and each other, in what is known as the “soil food web”.

First, plants put out exudates (carbohydrates and enzymes) to attract the appropriate microbes to their root zones. Bacteria and fungi feed on organic matter and chip away at sand/silt/clay particles to extract all the nutrients a plant could need, delivering them in exchange for plant exudates. However, nutrients are locked inside these bacteria and fungi until a higher trophic level ingests them and releases them in a soluble form that is available to plants.

More than nutrient cycling, beneficial microbes help keep pathogens in check. For example, predatory nematodes preferentially feed on the detrimental root-feeding nematodes, and beneficial fungi cover root hairs preventing root-rot fungus from invading. Bacteria and fungi also help build soil structure and help break up compaction, break down toxins, and increase the water-holding capacity of soil.

Unfortunately, most soils are damaged, and lack a complete and abundant soil food web. That’s where compost, compost teas and extracts can help. In combination with mulch, living roots year-round, and avoidance of chemicals/disturbance/compaction, we can build the soil, healthy plants, and healthy ecosystems.

Soil Biology matters. As Dr. Ingham says “Soil, without life, is Dirt”. … and dirt cannot support life. It is more important now than ever that we learn to grow our own healthy food, locally and sustainably.

It’s not always easy to troubleshoot compost and microbial amendments like compost teas/extracts. Join a growing movement towards bringing biology back in to soils by joining Compost Toronto!

Compost Toronto specializes in thermal aerobic composting because:

Many of us have studied under Dr. Elaine Ingham’s Soil Food Web School
Heat kills weed seeds
Turning keeps oxygen in the pile, favouring aerobic beneficial microbes and destroying pathogens
The techniques have been fine-tuned and proven through microscope testing to contain the whole soil food web in high numbers

But we are growing in to so much more!