Suo - Mires and peat vol. 67 no. 2 | 2016

In Finland peat is used in power generation, often burned with wood mixture resulting in mixed ash types. Peat ash is usually rich in phosphorus (P) but poor in potassium (K) and thus not as good fertilizer for peatland forests as wood ash. In this study we compared the effects of peat ash and peat ash with added potassium (potassium chloride or biotite) on the growth and nutrition of Scots pine seedlings on a cutaway peatland. In addition, peat ash was pelletized with biotite in one treatment. The treatments were applied around single trees with 10 replications. The study site was rich in N, but poor in P and K. Peat and foliar samples were analysed, and the height growth of seedlings was monitored for 17 years following the treatments. Pure peat ash had a positive effect on the growth of Scots pine but the survival rate of seedlings was not satisfactory. Peat ash enriched with potassium increased substantially growth of seedlings and increased the foliar K concentration compared to unfertilized control and peat ash alone. Pelletized peat ash and biotite gave similar results as the use of un-pelletized peat ash and biotite. Peat ash alone is not recommended for fertilization of Scots pine stands on drained peatlands. Adding K to peat ash enables recycling of large amounts of nutrients back to peatland forests, and is a good alternative to low-soluble P and K fertilizer. The granulation of the product would ensure good spreadability.

• Hytönen, Natural Resources Institute Finland, Silmäjärventie 2, 69100 Kannus, Finland E-mail: jyrki.hytonen@luke.fi
• Aro, Natural Resources Institute Finland, Itäinen Pitkäkatu 3, 20520 Turku, Finland E-mail: lasse.aro@luke.fi
• Issakainen, Ratapellontie 11, 91500 Muhos, Finland E-mail: ji@nn.fi
• Moilanen, Natural Resources Institute Finland, Paavo Havaksen tie 3, 90014, University of Oulu, Finland E-mail: mikko.moilanen@luke.fi

• Tolonen, E-mail: kimmotolonen38@gmail.com
• Vänskä, Helsingin yliopisto, Biotieteiden laitos, Kasvibiologian osasto E-mail: heino.vanska@helsinki.fi

• Hotanen, Luonnonvarakeskus, Joensuu E-mail: juha-pekka.hotanen@luke.fi
• Saarinen, Luonnonvarakeskus, Parkano E-mail: markku.saarinen@luke.fi
• Nousiainen, Luonnonvarakeskus, Vantaa E-mail: hannu.nousiainen@luke.fi

• Lindholm, Suomen ympäristökeskus E-mail: tapio.lindholm@ymparisto.fi
• Vesterinen, Metsähallitus, Luontopalvelut E-mail: pekka.vesterinen@metsa.fi

• Elo, E-mail: le@nn.fi
• Lindholm, Suomen ympäristökeskus (SYKE), Suojelualueverkostot E-mail: tapio.lindholm@ymparisto.fi
• Ovaskainen, Vapo Oy, Jyväskylä E-mail: juha.ovaskainen@vapo.fi
• Vasander, Helsingin yliopisto, Metsätieteiden osasto, Helsinki E-mail: harri.vasander@helsinki.fi