Survival, growth, and nutrition of tree seedlings fertilized at planting on Andisol soils in Iceland: Six-year results

A field trial was carried out in 1995 to study the effect of fertilization at planting on the survival, growth, and nutrition of tree seedlings planted on Andisol soils at two sites in South Iceland. Nine fertilizer treatments were tested on three tree species Betula pubescens Ehrh., Larix sibirica Ledeb. and Picea sitchensis (Bong.) Carr. After six growing seasons, seedlings provided with controlled-release-fertilizer (Osmocote®: 25 g per seedling) or smaller amounts of easily soluble nitrogen–phosphorus fertilizer (e.g. 1.2 g N per seedling and 1.4 g P per seedling) showed significantly improved survival and growth. Larger amounts of N increased mortality during the first year. Fertilized trees were less subject to frost heaving than untreated trees. In the year following application of NPK fertilizer the effect was insignificant on the foliar concentration of macronutrients of the fertilized seedlings, compared to control seedlings. It is concluded that fertilization during afforestation in Iceland and other areas in the world with similar climatic and soil properties could make the difference between plantation success or failure.