Mitigation of greenhouse gas emissions from an abandoned Baltic peat extraction area by growing reed canary grass: life-cycle assessment

Abandoned peat extraction areas are continuous emitters of GHGs; hence, abandonment of peat extraction areas should immediately be followed by conversion to an appropriate after-use. Our primary aim was to clarify the atmospheric impact of reed canary grass (RCG, Phalaris arundinacea L.) cultivation on an abandoned peat extraction area and to compare it to other after-treatment alternatives. We performed a life-cycle assessment for five different after-use options for a drained organic soil withdrawn from peat extraction: (I) bare peat soil (no management), (II) non-fertilised Phalaris cultivation, (III) fertilised Phalaris cultivation, (IV) afforestation, and (V) rewetting. Our results showed that on average the non-fertilised and fertilised Phalaris alternatives had a cooling effect on the atmosphere (-10,837 and -477 kg CO2-eq ha(-1) year(-1), respectively), whereas afforestation, rewetting, and no-management alternatives contributed to global warming (9,511, 8,195, and 2,529 kg CO2-eq ha(-1) year(-1), respectively). The main components influencing the global warming potential of different after-use alternatives were site GHG emissions, carbon assimilation by plants, and emissions from combustion, while management-related emissions played a relatively minor role. The results of this study indicate that, from the perspective of atmospheric impact, the most suitable after-use option for an abandoned peat extraction area is cultivation of RCG.