After the long winter many New Hampshire residents are faced with a different type of problem. An average cord of wood, depending on the efficiency of combustion and wood type, will yield approximately twenty pounds of ashes or the equivalent of one five-gallon pail. Over the winter, this can add up to quite an accumulation of wood ashes.
Wood ash acts on the soil much like limestone in that it raises the pH or alkalinity of the soil.
Consequently, many wood stove burners dump the ashes on their garden site with the thought that they are improving the soil condition of their garden. Yet unlike limestone, which can take six months or more to take effect, wood ash has high water solubility and quickly changes the soil pH. This can cause a problem with raising the soil pH over the optimum level of 6.5 to 7.0 if we spread too many ashes in the same area. A soil pH over the optimum level can affect plants as adversely as a pH that is too low. High pH will limit the uptake of important soil nutrients needed by the plant such as phosphorous, iron, and magnesium. A safe rate of wood ash application for a garden or lawn area would be twenty pounds per thousand square feet or a five-gallon pail full of wood ash.