• Parry Sound Nature Club

Fireplace Wood Ash Can Help Restore Your Soil

Before acid rain fell, central Ontario’s soils and waters got enough calcium—a mineral essential to life—to keep their vegetation and aquatic life healthy. But acid rain dramatically reduced the amount of calcium in our watershed.


The lower calcium levels in our environment left a sad legacy. Less calcium in our soils has reduced their fertility, harming many of our forests. Less calcium in our waters has disrupted many of our aquatic ecosystems. Water creatures that need large quantities of calcium, such as turtles, crayfish and many species of animal plankton have been particularly affected.


The Friends of the Muskoka Watershed’s ASHMuskoka community program aims to help you learn how you can reverse this damage, one hectare of soil at a time.


ASHMuskoka began by analyzing the ash generated by burning wood. They found that it’s 30 percent calcium and seven percent potassium—a mineral influential in sap flow, says Dr. Norman Yan, a director of the Friends of the Muskoka Watershed.


It went on to prove that calcium and potassium are chemically safe and biologically appropriate for replenishing potassium and restoring calcium levels to their pre-acid rain levels in our soil and water.


Along the way, ASHMuskoka reached out to the community to make sure that Muskoka residents generate enough wood ash to make a difference to the region’s forests.


“Our research showed us that residents want to participate in a nature-based solution to climate change, and are open to seeing, first-hand, that putting calcium-rich fireplace and woodstove ash into local forests can successfully restore the health of soils and forests,” says Yan.


In 2020, ASHMuskoka convinced some 1,200 local volunteers to “haul their ash,” as Yan puts it, to their local transfer station. There ASHMuskoka volunteers weighed it, analyzed it, screened it to clean out metal particles, and spread it on top of the fall leaves of 54 plots in three local sugar bushes.


A year later, the maple seedlings growing out of calcium-enriched soil had as much as 150 more percent calcium in their tissues.


Two years later, the leaves of mature trees showed healthy increases in potassium. More significantly, the additional calcium in their soil made the trees much healthier. The amount of chlorophyll in their leaves went up, enabling more photosynthesis, their wood got stronger, and the amount of calcium in leaves, roots and even seeds went up as well.


“Essentially, we woke these trees up,’ says Yan. “They had been napping for decades as a result of calcium depletion.”


ASHMuskoka’s next major initiative was to “awaken the forest” of maple, beech and hemlock in 10 hectares owned by Bracebridge’s Camp Big Canoe. In summer 2020 they added six tonnes of wood ash per hectare, and in 2021, they added two tonnes per acre.


The findings so far? Two tonnes of ash per hectare—the equivalent of one empty yoghurt container per square yard—can replace all of the calcium a forest’s soil has lost in 70 years of acid rain. Plus, maple trees growing out of ash-enriched soils can yield twice as much sap as before, and during high sap flow months of March and April, that sap is much sweeter. This change to sap flow is a recent observation and it will be interesting to see if it continues into the future.


Go to the ASHMuskoka website to find out where you can bring your ash, or to learn how to set up an ash recycling program on your property. One important tip for recycling enthusiasts: make sure your ash is completely cold and completely dry before you put it onto your soil.

Alternatively, you can contact katie@fotmw.org to join ASHMuskoka’s first Citizen Science ash addition project. ASHMuskoka volunteers will bring homogenized and analyzed wood ash to participants’ properties, measure its effects, and share what they learn.


Thanks to Yan, who provided this information at the Parry Sound Nature Club’s April 20 presentation.