Fertilization increased growth of Scots pine and financial performance of forest management in a drained peatland in Finland

Abstract

• All fertilizers containing phosphorus and potassium improved the P and K status and the stem growth of Scots pine still 26 years from application.• Wood ash, containing more nutrients than other fertilizers, gave the strongest stand growth response and the highest net present value.• Ash fertilizer treatment outperformed other fertilizer treatments and control in net present value, regardless of the applied discount rate, 3%, 4% or 5%. AbstractThe long-term effects of fertilization on the needle nutrient concentrations, growth and financial performance of a Scots pine (Pinus sylvestris L.) stand was examined in a thick-peated drained peatland forest located in Central Finland. At the trial establishment in 1985, the trees were suffering from P and K deficiencies, but their N status was good. The fertilizer treatments were Control, PK (rock phosphate + potassium chloride), ApaBio (apatite phosphorus + biotite) and wood ash, applied both with and without N and replicated six times. All treatments containing phosphorus and potassium increased foliar P and K concentrations above the deficiency limits up to the end of the study period of 26 years. The effect of the fertilization on stand volume growth of Scots pine was strong and continued still at the end of the study period. The trees on ApaBio and PK plots grew nearly two-fold and those on Ash plots over two-fold compared with the control plots. In a thinning made at the end of the study period the total logging removal on fertilized plots was 1.5-2.2 times greater and included more saw logs than on the control plots. Ash fertilizer treatment outperformed other fertilizer treatments as well as the control. With a 5% discounted equivalent annual income (EAI) of Ash fertilizer treatment was statistically significantly (p = 0.009) almost three times higher than that of control. As a conclusion, fertilization (either using PK fertilizers or Ash) in N-rich drained peatlands is a financially feasible method of management.

Comparison of granulated and loose ash in fertilisation of Scots pine on peatland

“…The Kannus site was a typical target for ash fertilisation in terms of high N content in peat and deficiency of P and K in the tree stand. The average growth of 2.9 m 2 ha -1 a -1 on control plots during the 15-year study period was similar to that reported by Moilanen et al (2015) for an unfertilized stand. Loose ash increased stem volume growth 2.2-fold, and granulated ash and PK fertiliser 1.7-1.8-fold compared to the control over the 15 years.…”

“…For example, Moilanen et al (2012) reported a 3-fold growth increase following loose ash fertilisation after only 10 years at an N-rich drained peatland site. Moilanen et al (2004Moilanen et al ( , 2015 also found that in N-rich pine peatland, ash fertilisation more than doubled stand growth in 15-26 years. All the previous results (Moilanen et al 2002(Moilanen et al , 2004 suggest that with a high peat N concentration like this study's Kannus site, the impact of ash fertilisation on tree growth will exceed the 15-year study period.…”

“…Ash is currently estimated to be spread annually on more than 10 000 ha. Long-lasting effects of loose wood ash on the nutrient pools in surface peat, and on the nutrient status and growth of conifers growing on nitrogen rich peatlands have been reported in many studies (Silfverberg 1996;Silfverberg and Hotanen 1989;Moilanen et al 2002Moilanen et al , 2004Moilanen et al , 2005Moilanen et al , 2015Hökkä et al 2012). Loose ash fertilisation in N-rich drained peatlands is also a financially feasible management method Ahtikoski and Hökkä 2019).…”

Productivity of mechanized wood ash application in forest

“…Wood ash is considered even better than the commercial fertilizers because of slower nutrient release. Moilanen (2015) concludes that wood ash fertilization is economically feasible and already during commercial thinning annual income was three times higher than in control (Moilanen et al, 2015). Studies in Latvia also reveal that ash fertilization on drained organic soil induced additional volume increment from 2 to almost 5 m 3 ha -1 per year (Okmanis et al, 2016).…”

Initial evaluation of impact of evenness of spreading wood ash in forest on additional radial increment

“…Increasing demand and removals of biomass require to improve the tree growth conditions, for example, by proper thinning, amelioration and other forestry operations, however productivity of forest stands can be significantly increased by fertilization [1][2][3]. Another issue related to biomass consumption is utilization of wood ash, which so far is mostly considered as waste.…”