Irrigation and Fertilization of old Norway Spruce on Outwash Plain in Gludsted Plantation, Jutland

1988

S. 3-14

3 Abb., 4 Tab., 19 Lit. Ang.

Unselbständiges Werk

200006916

In 82-year-old Norway spruce in Gludsted plantation a (Figure 1). Timber measuring data at the establishment appear from Table 1. Table 2 shows the precipitation measured and the quantities of irrigation water employed during the 4 growing seasons covered by the experiment. The fertilization consted of an annual supply of 336 kg per ha of the NPK- fertilizer 23-3-7 with Mg andCu. Table 3 contains an overall survey of the experimental results. The fertil ization has had no effect, but the irrigation has increased the basal-area increment by 33-34%, the height increment by 34-37%, and the volume increment by 28-31%. The latter means 3.2 m3 per ha and year. In Figure 2 the mean excess increment in irrigated and fertilized + irrigated plots has been superimposed year by year on the mean increment on controls and fertilized plots. Where the increment in these plots is high, the excess increment due to irrigation is relatively low and vice versa. The basal-area increment computed on the basis of annual- ring analysis confirm the other timber measuring results, and new annual- ring indexes for this forest district agree very well with the experimental results (Figure 3). Stump-surface estimation of the attack grade of Heterobasidion annosus has, as was expected, revealed no influence of the treatments. 57% of the stump-surfaces show attacks and 40% show heavy attacks (attack grades 3 and 4). High pruning of trees in belts around the experimental area (hatched parts in Figure 1) seems to have protected the area effectively against windfalls. Immediately after the pruning some trees dies as a result of heavy attacks of Ipstypographus. fertilization/irrigation experiment was established in the spring of 1983