Effects of nitrogen fertiliser on radiata pine growing on pumice soils.

Authors: I. R. Hunter, J. D. Graham, K. T. Calvert
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1985, Issue N.Z.J.For. 30(1) 1985, pp 102-114, May 1985
Publisher: New Zealand Institute of Forestry

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Abstract: This paper presents and discusses the most recent broad find-pings from fertiliser trials on the pumice plateau. Response to N alone occurred over most of the pumice soils. However, the higher altitude flow tephra sites of southern Kaingaroa did not respond to N alone, but did respond to mixed fertiliser containing N, P, K, Mg and B and responded in some places to Mg fertiliser. No height response to N fertiliser was found in any trials; basal area responses have been observed only where the canopy still had room to expand, as a result of prior thinnings or pruning. A fertilised stand that was allowed to remain in a very highly stocked state to age 23 showed higher mortality than in the parts of it left unfertilised. In one detailed study of tree shape change in recently thinned 15-year-old radiata pine, diameter increment at intervals up the tree differed fairly consistently between fertilised and unfertilised plots over 80% of the tree length.

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