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Environmental Considerations
Although application of wood ash to forests, agricultural fields, or mine spoils is generally beneficial and an efficient way to dispose of ash from woody biomass, there are several environmental concerns worthy of consideration.
  • Most heavy metals present in the wood tend to vaporize during combustion.
  • The remaining mineral content contributes to ash formation. Should levels of heavy metals be high, recycling of ash as fertilizer is restricted by environmental legislation. 
  • This is the case because the metals may leach into ground water or be absorbed by crops. 

More modern furnaces are often equipped with filters to reduce heavy metal emissions, but it is best that painted or treated wood waste be avoided as a fuel source considering the higher heavy metal concentrations found in these sources. Wood ash used as a soil amendment should originate from the burning of forest residues or untreated wood only.

 
 
 
   
 
       

This concludes Unit 5: Ash Content and Management. To proceed to the Module 6 Post Test, click the Next link.

 

 

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"A program of the Cooperative Extension Service funded by the Renewable Resources Extension Act"
Last Updated: November 11, 2007