Fertilisation in South African Forestry

Abstract

The history of forestry fertiliser research in Southern Africa is described briefly. Fertiliser investigations in wattle started in the 1920s and in pines in the 1930s, but investigations with eucalypts started only in the 1950s. Nevertheless, it is noted that today more is known about the nutritional requirements of eucalypts than of the other species, mainly owing to the application of foliar analysis in combination with suitable experimental designs. The importance of the various nutrients for the different species is discussed with reference to experiments undertaken in Southern Africa. The controversial issue whether gains from fertilising are maintained is examined and the conclusion is reached that unsatisfactory design and insufficient replication are the main causes that initial responses have not been shown to be maintained. An indication of the commercial use of fertiliser in wattle, eucalypt and pine growing is given and the high profitability of fertilisation for these species indicated, showing it to be the most economically beneficial operation in silviculture.