Composting Bonfire Ash
Some allotment sites that had banned bonfires over the summer, to avoid inconveniencing local householders who were at home and had their windows open to increase ventilation have now lifted the bans. I am in favour of shredding and composting organic waste rather than burning it but if bonfires are being used the wood ash produced can be rescued and composted.
Wood ash from bonfires of plant waste, hedge cuttings and pruning’s can be composted as can ash from paper or cardboard and untreated and unpainted wood. It is not advisable to compost ash from bonfires that have included treated or painted wood, synthetic materials, and plastic.
Wood ash is high in potassium, and contains phosphorous as well as manganese, iron, zinc, and calcium but the main feature in respect to composting is that wood ash is alkaline so it will reduce the acidity of the compost bins containing significant amounts of kitchen waste and grass mowings creating a better environment for composting worms.
However, the quantity of wood ash added to the bin should be limited to a thin layer, or handful, every 6 inches (15cm). The ash should be carefully mixed or scattered so that it does not clump, resulting in an anaerobic area within the bin. If substituting wood ash for lime in one of the traditional composting layered system, it is about half as effective as lime in neutralising acid.
It is best to avoid composting or collecting ash on windy days, when the ash is likely to be blown over the site and eye protection might be advisable . Gloves should be worn as the ash may cause skin irritation.
If collecting wood ash for a community composting site, or intending to store it, use a sealed metal container, as the nutrients are water soluble and hot ashes may melt plastic. Do not scatter wood ash over one of the site Reception bins.