Application of potassium and nitrogen fertilizers in young spruce stands (Picea abies Karst.)

Abstract

In young spruce plantations on mineral soils the growth of the trees is improved by N application only in rare cases, and by P or K application only on sites over parent rock, which is poor in available fractions of these nutrients. Interpretation of a field trial showed that on extremely poor quartzitic soils potassium deficiency limited growth during the first years of crop development. Potassium deficiency ended at pole stage (about 15 years after planting). N deficiency began at sapling stage (about 8 years after planting) and increased later. On quartzitic and similar sites with a low cation-exchange capacity, appropriately phased applications of K and N markedly improve the site index and yield level of young spruce stands. Thus, it was shown that the stock of stemwood can be raised from 3 to 13 m³ per ha up to an age of 16 years.