Effect of fertilization on the nutrient status and growth of Scots pine on drained peatlands in northern Ostrobothnia and Kainuu

1993

37 S.

zahlr. Lit. Ang.

Bandaufführung

37343

The effect of single and repeated fertilization on the nturient status and stemwood growth of Scots pine on drained peatlands was investigated in the study. The magnitude of the growth increment obtained with single fertilzation depended on the nitrogen content of the substrate. On nitrogen- poor peatlands (N content of the surface peat below 1.75 %) PK fertilization increased the volume growth of pine during the 7-year period by only 0.2-0.3 Kubikmeter/ha/a. NPK fertilization gave a corresponding increase of 0.7-0.9 Kubikmeter/ha/a. The effect of NPK was at its greatest 3-5 years after fertilization, and gabe a measurable stand growth increase for about 10 years. The effect of fertilization was reflected in the needles as slightly elevated P and K concentrations. On nitrogen-rich peatlands (N content of the surface peat over 2.1 %), both the PK and NPK treatments resulted in a strong growth reaction that was still continuing at the time the stands were measured (7-12 years after fertilization). During the 7-year period after ferilization the growth on the PK plotswas about 60 % and on the NPK plots about 70 % greater than that on the unfertilized plots. At its highest the annual growth increase was 2-4 Kubikmeter/ha depending on the experiment. Macronutrient fertilization clearly increased foliar P and K contrations, and decreased the N concentrations. Fertilization also resulted in a decrease in the B, Mn, Zn, Bg and Cu concentrations. The effect of repeated fertilization on the nitrogen-poor sites was similar to that in the stands fertilized only once. The growth increment obtained during the first 10-year period following the second application of the basic PK fertilizer, 10-15 year after the first treatment, was less on the nitrogen-rich sites than that given by the first application. A marked reaction (0.7-1.4 Kubikmeter/ha/a) only occured after NPK treatment. The reason for the modest reaction (0-0.8 Kubikmeter/ha/a) of the repeated PK treatment is most probably due to the fact that the basic PK ferilization continued to have an effect during the period when fertilization had been repeated.