Recent research co-authored by our Trent University collaborator, Dr. Shaun Watmaugh and led by his M.Sc. student, Holly Deighton**, has definitively shown that dosage levels of 6 tonnes per hectare of wood ash addition to forest soil resulted in significant increases in soil pH and calcium and magnesium concentrations. The level of response, however, varied by treatment. Foliar concentrations of base cations in sugar maple seedlings significantly increased in ash treatments and there was no significant treatment effect on foliar metal concentrations or seedling growth. In roots and shoots, concentrations of several metals (manganese, aluminum, iron, boron, arsenic, cadmium, zinc, copper, lead, chromium, and nickel) increased after ash application, however response was most pronounced in yellow birch ash.
These results suggest that application of non-industrial wood ash can counteract the lasting effects of acid rain by increasing soil pH and base cation concentrations, as well as increasing sugar maple seedling foliar nutrient concentrations, but ashes from species with high metal contents may also increase metal availability to vegetation, at least in the short‐term.
The research cited suggests we should see real benefits from our ash additions, both the one completed in the fall of 2019 and the upcoming larger-scale addition in 2021. With such positive results after only 3 months, it means we are on the right track in the revitalization of our local forests which have been impacted by acid rain. It also means that proceeding with our larger-scale deployment will not be problematic with respect to levels of metals concentrations in the ash as they do not exceed provincial regulations. Given the conclusions of this early research, we anticipate extremely positive results with our larger-scale deployment of between 6 and 8 tonnes per hectare, results which may not only “wake up” the currently napping forests but also increase transpiration rates and have a positive impact on the ability of the forest to mitigate the effects of increasing levels of precipitation in the region.
**Holly D. Deighton and Shaun A. Watmough, Effects of Non‐Industrial Wood Ash (NIWA) Applications on Soil Chemistry and Sugar Maple (Acer saccharum, Marsh.) Seedling Growth in an Acidic Sugar Bush in Central Ontario in Forests 2020, 11, 693; doi:10.3390/f11060693
