Ash produced in wood stoves, on-farm boilers, and maple syrup operations can be used on-site without testing the ash. There is little reason to worry about metal contamination from ash produced in these types of stoves since these operations do not filter out fly ash. Producers should use the following average wood ash composition:
- Calcium carbonate equivalent( CCE): 50 %- Soluble potash( K2O) content: 6 %- Calcium content: 25 %- Magnesium content: 5 %
Producing Ash Small-scale ash producers should take care when selecting wood feedstocks. Chemically preserved wood should not be used for ash due to the copper content of the preservatives. While most pallets are an acceptable input, painted pallets and pallets labeled " MB " or " SF " should not be used in small burners because they contain pesticides which can be harmful if inhaled. Pallets labeled " HT " and unlabeled pallets are heat treated and are acceptable feedstock but make sure to sift ash for nails. As with pesticide-treated wood, creosote-preserved wood( e. g. railroad ties) is unsuitable for small scale burning since it contains many toxic compounds.
Reprinted from UMass Extension Hort Notes 2025 Vol. 36:10