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5.12 Fertiliser use
Authors: D J MeadPublication: , Volume Section 5 – Plantation silviculture, pp 12, Dec 2023
Abstract: Fertiliser has been used as a silvicultural tool in forest plantations in New Zealand from the mid 1950s. Its use began with the application of superphosphate to correct severe phosphorous (P) deficiency in Northland radiata pine stands. Today many of these plantations only need smaller maintenance applications. Later the correction of boron (B) deficiency became common, particularly in the South Island. Nitrogen (N), potassium (K), magnesium (Mg) and copper (Cu) are also applied, sometimes routinely (Will 1985; Mead 2013; Davis et al. 2015). Zinc, iron, manganese and molybdenum only occur rarely in New Zealand plantations. Fertilisers also often supply calcium (Ca) and sulphur (S) and, although these nutrients may sometimes be helpful, they are not deliberately applied to correct deficiencies. Liming to increase soil pH is not required as most plantation trees in New Zealand are adapted to low pH soils. In pastoral agroforestry situations the pasture component may well need fertilizer but this is not discussed here. The use of fertilizers in New Zealand plantation forests has decreased since the mid1980s but there is potential for greater use to increase productivity or maintain nutrient pools (Smaill and Clinton 2016).