A number of experiments, using both field trial and pot trial techniques, were undertaken to investigate the effect of N addition at high rates on the growth and nutrition of radiata pine. Two field trials were designed to investigate the effect of increasing rates of N addition on young radiate pine plantation (Taheke) growing in a fertile ex-pasture soil north east of Rotorua and the effect of increasing rates of N and B addition on young radiata pine growing in the nutritionally poorer soils of Ashley Forest in Canterbury. One pot trial in sand culture investigated the effect of N source on the growth of radiata pine seedlings while a further two pot trials investigated the effect of increasing N and B addition at two rates of P. In 1989 urea was added at 0, 250 or 500 kg N ha⁻¹ to enhance the mild stem deformities that had been observed in young radiata pine trees at the Taheke site. The soil had a high nutrient status, presumably because of its pastoral land-use history, a high potential to nitrify and the major form of inorganic N was nitrate. While the amount of radiata pine stem deformity did increase during the trial, this was not a result of the fertiliser addition. The measurements of tree height and diameter were also not significantly affected by N addition. Subsequent soil analysis indicated that the amount of native N in the top soil was already high, approximately 3.1 and 1.8t ha⁻¹ in the 0 to 10 and 10 to 20cm depths respectively, and therefore the fertiliser additions did not represent a large input to the system and the addition of N did not significantly affect the amount of total N% or mineral N in the soil. At Taheke, the increasing addition of N significantly increased the foliar concentrations of N in the short-term and significantly decreased the concentrations of P, Ca and Mg during the trial presumably as a result of dilution and/or translocation. There appeared to be a relationship between Cu and N, in the foliage, and the number of kinks in the upper stem of the radiata pine trees. As Cu:N ratios in the foliage increased, the number of kinks decreased. The characteristics of the trial site at Ashley Forest contrasted to those at Taheke because the soils had a low nutrient status, had a very low potential to nitrify and the major form of inorganic N was ammonium. The B status of the soil was also marginal for radiata pine growth. The fertiliser treatments consisted of N, added as urea, at 0, 200 or 400kg N ha⁻¹ by B, added as ulexite, at 0, 3.7 or 7.4 kg ha⁻¹. The foliage sampling technique followed the life of fascicles from just after initiation in November, 1989, to full extension in May, 1990. The results showed that the concentrations and of amounts per fascicle of N and B significantly increased in response to the addition of the respective fertilisers while P and Mg significantly declined with increasing N addition. Retranslocation occurred for both P and B particularly during times of low soil moisture. The amount of retranslocation was increased with increasing N addition while the increasing addition of B reduced the amount of B retranslocation. The results indicated that without B addition the foliar concentrations of B were marginal (i.e. 8 to 12µg g⁻¹) and were further reduced by the addition of N. This also occurred for P where the foliar concentrations were low (i.e.