For many, life in the chalet rhymes with a fireplace. Wood heating is a great way to keep your chalet warm at a low cost, and instantly create an atmosphere so characteristic of chalet life.

According to the data available, there would be any loan of 200,000 cottages and forest camps in Quebec. It is estimated that more than 650,000 Quebec households use wood for heating. For a third of these households, wood is the main source of energy for heating. This results in an annual amount of wood consumed in the order of more than 5 million tonnes.

However, the combustion of firewood generates an average of 1.5% ash (dry weight), or more than 75,000 tonnes of ash from domestic wood stoves annually.

In urban and rural areas, the use of wood as the main method of heating is increasingly contested because of the atmospheric emissions associated with it: fine particles, dioxins and furans and polycyclic aromatic hydrocarbons (PAHs). All of the elements recognized as carcinogenic.


Little is known about the disposal of ashes in Quebec. In urban areas, most of the ashes are considered to be discarded or spread on residential lots or in surrounding woodlands.

Ashes are recognized as a substitute for agricultural lime and potassium and phosphorus fertilizers. It is for this reason that they are used in organic farming. However, it must be ensured that they do not contaminate the soil, particularly because of their high levels of heavy metals.

Agronomic guidelines suggest not to apply more than 70 g per square metre at a time, which is the equivalent of 1/3 cup. In addition, it is recommended not to apply more than 2 cups per square metre every three years, and to avoid the application on soil with a pH greater than 7.

Cooled (3 weeks), they can also be inserted in the domestic composter or in the organic waste collection bin when the service is available. Adding ashes would speed up the composting process, raise the pH, raise the temperature, absorb moisture and decrease odours. This addition must, however, be spread over time and in a small quantity, i.e. not more than 4% w / w.

Environmental Risks for Lakes

The spreading of ash on riparian land is not without environmental risks for lakes. As wood ash has real agronomic properties, including high concentrations of phosphorus, its use requires close supervision. We know that the presence of sources of phosphorus around lakes is to be avoided because of its negative effects on the accelerated ageing of these.

For this reason, it is suggested to avoid spreading ash directly on riparian land, in particular when the slope of the land is significant (15% and more), so as to avoid the leaching of the phosphorus contained in the ashes towards Lake. The same is also true for all fertilizers whether organic, minerals or compost.

Needless to say, you must avoid dumping your ashes on the roads or in their ditches at all costs.

The best practice for wood ash is to bury it in the ground. In fact, the chemical reactions between phosphorus and the soil, in particular in the soils north of St. Lawrence (Laurentians), slow down the mobility of phosphorus through chemical adsorption processes.

Second, it is still possible to spread wood ash on soil surfaces when these are delimited by flower beds, which limits the transport of the ash to the lake.


Although domestic wood ash has significant agronomic value, it is not recommended to be used on riparian land unless it is buried in the ground or spread in environments that limit runoff.

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