REGULAR ARTICLE Dynamics of uptake, distribution and utilization of nitrogen applied at different times after planting in a Eucalyptus grandis plantation S. J. Rance & R. J. K. Myers & D. M. Cameron Received: 17 June 2008 / Accepted: 26 February 2009 / Published online: 12 May 2009 # Springer Science + Business Media B.V. 2009 Abstract N fertilizer labelled with 15 N was used to follow the accumulation and distribution of N applied at different times after planting Eucalyptus grandis W Hill ex Maiden seedlings in south-eastern Queensland, Australia. The first application was made to selected trees at 0.12 y after planting (T 0 ), and treated trees were harvested at intervals after. Further labelled applications were made on different sets of trees 0.50, 0.74, 1.30 and 1.49 years after T 0 ;T 0.5 ,T 0.74 ,T 1.30 and T 1.49 respectively. After 0.5 y there was no significant difference in growth between T 0 trees and unfertilized controls, but after 1 y above-ground biomass and N content of the controls was only 30% and 39% of the fertilized trees respectively (P <0.05). At later applica- tions controls were not significantly different from fertilized trees up to 1 y later, but after 2 y above- ground biomass and N content was reduced (P <0.05). Growth reductions occurred after leaves present on the tree at the time of fertilizer application were shed. Leaf biomass and N content increased steadily to age 1.5 y and then stabilized at about 2.5 kg tree -1 and 35 g tree -1 respectively, new growth balanced by litter fall. N content in woody material (stems+branches) in- creased steadily, equaling that of the leaves at 3.5 y. N derived from fertilizer and the proportion of applied N recovered peaked at 1 y and then decreased. These relationships were not affected by time of application. In T 0 trees N in above-ground parts derived from fertilizer increased steadily to 42% of the total 0.5 y after application. It then decreased rapidly after leaf fall commenced while total N content increased. When observations ceased 3.5 y after planting, less than 5% of the N in the trees was derived from fertilizer. N uptake was two-phased. In the first year mineral N from the fertilizer was taken up by the trees. In subsequent years fertilizer contributed to the tree growth but the N taken up came from a different source. Keywords 15 N . Eucalyptus grandis . Nitrogen content . Recovery Plant Soil (2009) 324:241–252 DOI 10.1007/s11104-009-9951-y Responsible Editor: Hans Lambers. S. J. Rance (*) CSIRO Sustainable Ecosystems, CSIRO Centre for Environment and Life Sciences, PO Box 5, Wembley, Western Australia 6913, Australia e-mail: stanley.rance@csiro.au R. J. K. Myers CSIRO Sustainable Ecosystems, Queensland Bioscience Precinct, 306 Carmody Rd., St. Lucia, Queensland 4067, Australia D. M. Cameron Sustainable Forestry Program, School of Environmental Science and Management, Southern Cross University, PO Box 157, Lismore, New South Wales 2480, Australia