Some Effects of Nitrogen and Phosphorus Fertilization of Pinus Pinaster in Western Australia

Fertilization of Pinus pinaster on a lateritic gravelly soil with urea and superphosphate increased the size of current needles and their nitrogen and phosphorus concentrations within 6 months of application. Girth increments after 18 months were increased up to threefold. The photosynthetic ability of needles up to 5 years old was increased, although the effect was greatest in 1- and 2-year-old needles. This effect was associated with higher concentrations of nitrogen, phosphorus, chlorophylls 'a' and 'b', and moisture in the needles. Stem growth during the dry summer was maintained at a constant rate, whereas in untreated trees stem growth ceased for the 2 hottest months.