Wood ash can be beneficial to the soil of your garden. If you have a combustion heater, or use an open fire in your home, collecting the wood ash is a good idea, as it can be utilized, rather than discarded.
Using ash as a liming agent
Wood ash basically consists of potassium, calcium, and magnesium. The presence of calcium means that it can raise the pH levels of soil, and so it can be used on acid soils instead of lime. It is especially effective around flowering plants, but be careful of the following situations if you choose to employ it in the garden:
* If you are using treated pine as fuel. (You shouldn’t be doing this anyway, as treated pine gives off dangerous chemical fumes when burnt).
* Some charcoals or briquettes have added chemicals to speed up the burning. he ash collected from these products should not be used. Check the product first to make sure this is not the case.
* Don’t add ash if you have alkaline soils (pH > 6.5). Most Australian soils are acidic (pH < 6), except for some areas around Adelaide and Perth that have limestone soils (good for wine though!).
For more information on testing the pH level of you soil, you can try here. It is a wise move to know the pH level before you start any attempt to amend the soil.
How much do I use?
For the average soil, you can add one shovel full (or approx. 1kg) to every square meter of soil. To apply, simply spread it out, and work it into the soil so that it doesn’t blow about in the wind.