Ash Products and Their Economic Profitability

Abstract

Sustainable whole-tree harvesting practice requires that nutrient removal from the forest is compensated. Wood ashes contain all the nutrients, except for nitrogen, that are found in unburned fuel and can also increase soil pH, which makes ash recycling a natural way to stabilize the nutrient balance and counteract the acidification of forest soils that occurs due to intensive forest management. Several methods for processing ashes into spreadable products have been developed. The aim of this paper is to compare these methods. The study mainly focused on an economic evaluation of production, transportation and the spreading of self-hardened ash, ash pellets and ash granules. Self-hardened ash is generally considered to be the cheapest alternative to manufactured ash products, but these results imply that the most cost effective alternative is ash pellets. Around 27% of total costs could be earned from recycling the ash by producing pellets and 8% if granules are produced instead of self-hardened ash. This partly depends on the higher density of the pellets and granules and a significant reduction in the number of transportation operations. The reduction in transportation operations and diesel consumption also has major environmental benefits. Furthermore, it is more efficient to produce granules and pellets than it is to produce self-hardened ash and it is also easier to produce a reliable product of an appropriate size, shape and texture for a market that has well defined requirements.