Fertilizer and irrigation treatments (with and without) were applied i
n factorial combination for 3 years to Eucalyptus grandis (four seedlo
ts) planted near Gympie, Queensland. Timing and quantity of fertilizer
applications aimed to ensure that nutrient availability did not limit
growth during this period. Tree growth in both height and basal area
was significantly increased by fertilizer treatment but was not affect
ed by irrigation. Nitrogen contents of above-ground components were es
timated in one of the four seedlots. Foliage was the major sink for ni
trogen accumulation during the first 3 years in both unfertilized and
fertilized trees, but the importance of foliage declined as tree size
increased. Annual net rate of nitrogen accumulation in fertilized plot
s was highest during the first year (150 kg ha-1) and was an order of
magnitude greater than in unfertilized plots. The net rate of nitrogen
accumulation in fertilized plots decreased rapidly after the first ye
ar whereas only minor differences occurred in unfertilized plots. Tree
growth in unfertilized plots was severely limited by poor nutrient av
ailability over all 3 years studied. Net primary production was direct
ly related to mean canopy nitrogen content. In this experiment, each k
ilogram of nitrogen in foliage was associated with a production of 220
kg of above-ground dry matter each year, regardless of fertilizer tre
atment.