Wood ash is a by-product of the wood industry resulting from burning of wood residues for energy production (Nkana et al. 2002). Most of the inorganic nutrients and trace elements in wood are retained in the ash during combustion; the quality of the end product depends on the quality of the wood, the tree species, and the burning process (Perkiomaki et al. 2004). The ash and the metal contents are generally higher in bark than in stemwood (Hakkila 1986; Werkelin et al. 2005). Fly ash contains higher levels of dioxins and heavy metals than the bottom ash (Pitman 2006). For agricultural and horticultural purposes, only bottom ash should be used according to Stockinger et al. (2006). Wood ash is a significant source of the nutrients phosphorous, potassium, magnesium, and calcium, and its properties resemble those of lime (Naylor and Schmidt 1986; Ohno and Erich 1990). Ash fertilization can compensate for the nutrient losses caused by harvesting operations, nutrient leaching, and soil acidification (Saarsalmi et al. 2006).