What Is Wood Ash?
Wood ash is the inorganic and organic residue remaining after combustion of wood or unbleached wood fiber. The physical and chemical properties of wood ash vary significantly depending on many factors. Hardwoods usually produce more ash than softwoods, and the bark and leaves generally produce more ash than the inner woody parts of the tree. On average, the burning of wood results in 6 to 10 percent ashes. When ash is produced in industrial combustion systems, the temperature of combustion, cleanliness of the fuel wood, the collection location, and the process can also have profound effects on the nature of the ash material. Therefore, wood ash composition can vary depending on geographical location and industrial processes. This makes testing the ash extremely important. Ash is composed of many major and minor elements that trees need for growth (Table 1). Since most of these elements are extracted from the soil and atmosphere during the tree’s growth, they are common in our environme
