The effect of granulated wood-ash fertilization on soil properties and greenhouse gas (GHG) emissions in boreal peatland forests

The amount of wood ash produced in power plants is increasing with increasing use of forest biomass in energy production. Wood ash can be recycled as fertilizer especially in boreal peatland forests naturally rich in nitrogen. Improved nutrient availability and increases in soil pH can enhance microbial activities, decomposition of organic matter and greenhouse gas (GHG) emissions. We studied the effects of granulated wood-ash on soil chemical properties, vegetation characteristics, decomposition rate and fluxes of nitrous oxide (N2O) and methane (CH4) in boreal peatland forests. In addition to the field measurements, we conducted laboratory experiments. Wood-ash fertilization changed soil chemical properties, altered understory vegetation, increased tree growth and decomposition rate but there were no significant changes in the N2O and CH4 fluxes in situ, whereas in laboratory incubations ash decreased the N2O production rate. The results show that there is no major risk of increasing GHG emissions after granulated wood-ash fertilization in boreal peatland forests.