Petaja, G., Okmanis, M., Makovskis, K., Lazdiņa, D. and Lazdiņš, A. 2018. Forest fertilization: economic effect and impact on GHG emissions in Latvia. Baltic Forestry 24(1): 9-16.

    The research objective was to estimate how the application of nitrogen fertilizer and wood ash in state forests can influence the additional volume increment and to determine the economic impact and national level climate change mitiga-tion potential of the forest fertilization practice. National forest inventory data was used to select stands that are suitable for fertilization with ammonium nitrate and wood ash. Forest management restrictions are not considered; therefore, the study represents theoretical values of the additional income and the national climate change mitigation potential. According to the study, applying 436 kg ha-1 ammonium nitrate (30% of nitrogen) at 2.0 thous. ha of forests annually increases the additional volume increment by 28 thous. m3 in the 10th year, but cumulative increment is 142 thous. m3. Application of 5 tons of wood ash per ha at 4.3 thous. ha of forests annually increases the additional volume increment in the 10th year by 58 thous. m3, but cumulative increment during the period of 10 years is 290 thous. m3. Internal rate of return (IRR) for the nitrogen application in 20 years from the project start-up is 11%, but for ash application is 13%. The impact on gross domestic product reaches its maximum (3.2 million € per year) 11 years after project start. Cumulative reduction of greenhouse gas emissions in national inventory due to forest fertilization can reach 635 thous. CO2 eq. in 10 years. Forest fertilization would contribute to CO2 sequestration equivalent of 12.7 million € in 10 years. The value of additional CO2 removal is equal to 156€ ha-1.

Keywords: forest fertilization, wood ash, nitrogen, volume increment, CO2 removals, internal rate of return.