EucFERT – a fertiliser decision tool for plantation eucalypts in Tasmania Paul Adams 1 , Tim Osborn 2 and Peter Volker 1 1 Division of Forest Research and Development, 2 Division of Forest Management, Forestry Tasmania, GPO Box 207, Hobart 7000 Australia Abstract Effective nutrition management is vital for optimising productivity in many eucalypt plantations, to protect the large investment in pruning for solid wood production and meet long-term woodflow targets. A fertiliser decision support tool, EucFERT, has been developed which is helping forest managers to maximise growth responses while being economic and minimising off-site nutrient losses. The tool uses detailed local soil information along with crop and site data to provide guidance on a stand basis. Predicted growth responses to fertiliser are based on long-term nutrition experiments covering early-rotation and mid-rotation trials across a range of site and soil types. Outputs from EucFERT can be used to prepare Stand fertiliser management plans that include soil and site management, fertiliser product, rate, application, frequency and timing, along with environmental and operational cautions relating to aerial application. The use of this computerised tool provides much greater confidence in fertiliser decision-making and formalises the decision process, with decision criteria and resulting recommendations available for storage for future reference / auditing. Ongoing research will contribute to further refinement of EucFERT including improved predictions of weed impacts, nutrient loss potential, inter-rotation and slash management options, and improved integration with other Forestry Tasmania decision support tools. Introduction The need for improved management of nutrition in E. globulus and E. nitens plantations in Tasmania is widely recognised. Low availability of soil nitrogen (and phosphorus) is a major limiting factor across a significant part of the plantation estate. On lower productivity sites, lack of sufficient nitrogen often results in failure of the tree crop to produce a commercial quantity of wood. This manifests as a decline in growth, vigour and leaf area, often within 2 – 3 years of planting, along with reduced apical dominance and dying lower branches. It is important to avoid such decline of eucalypt health and growth, as the ability to recover from this position with fertiliser can be very difficult once the trees have entered this stage (Dell et al. 2001). This also represents a lost opportunity to increase productivity through improved nutrition. Re-invading weeds in these low productivity plantations often exacerbate the problem and make ‘rescue’ treatments very expensive. Therefore, the objective of soil and nutrition management is to avoid growth decline, increase productivity and improve sustainability of plantations in the long-term. This is achieved through soil classification, monitoring plantation performance and timely fertiliser application. The size of the current plantation resource managed by Forestry Tasmania is approximately 34,000 ha and consists of E. nitens and E. globulus (Forestry Tasmania 2006). These plantations are primarily managed to produce solid wood products (including high quality sawlogs) on 20 – 30 year rotations with the aim of providing significant volumes toward legislated supply commitment of 300 000 m 3 / yr (Forestry Act 1920 Section 22) within the next decade. Currently these products are being supplied from native regrowth and old-growth forests. Due to increased reservations as a result of the Regional Forest Agreement (1997) and Tasmanian Community Forest Agreement (2005) intensive silvicultural management of plantations is required to meet these commitments. In plantations this includes pruning to 6.4 m and thinning to a residual stocking of 300 - 350 pruned stems/ha (Wood et al. 2007, this conference). Adequate growth rates are required to maximise product and volume yields and fertiliser application which is appropriate to site, soil and crop characteristics is vital. Most of the plantations have been established on sites following harvesting of native forests. At many of these sites, soils have low organic carbon, nitrogen and phosphorus availability. Other nutrients such as Mg and K and micronutrients can be limiting on some sites. There can also be complex