An exploratory study into ash mobilization using lysimeters

Wildfires burn vegetation and leave the resultant organic and inorganic ash into the soil surface. Depending on the temperatures and burn durations, the quantity and type of ash can vary widely. Ash mobilization following wildfire is a topic of major concern, since it may result in contamination of surface water bodies within and downstream of the burnt areas.

The present study aims to analyse the influence of black and white ash on surface runoff, leachate and total erosion and erosion of organic matter by running a field experiment along 6 weeks, using three replicate lysimeters with control soil, soil with addition of black ash and soil with addition of white ash. There was some suggestion but no statistical evidence that black ash reduced overland flow generation during the initial rainfall events, while black ash was found to increase sediment and organic matter losses by overland flow in a statistically significant manner. This was not during the initial rainfall events and, therefore, not directly related to the presence of a homogenous cover of a well-defined ash layer on the soil surface.