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Well-designed agricultural decision support tools (DS) equip farmers with a rapid, easy way to compare multiple scenarios as well as the influence of different management strategies on crop production. One such tool, CropARM (http://www.armonline.com.au) assists users in establishing a framework of risk, with simulations incorporating climate scenarios and management actions, such as fertiliser rates, sowing time, row spacing, and irrigation regimes. When used in conjunction with soil and climate characteristics, biophysical model-based DS tools provide information that complements farmer experience and helps establish a framework for risk management given local climate characteristics. In this study, we used the APSIM model to provide the simulation data necessary to expand CropARM for new management conditions and environments in southern Australia. Prior to this work being undertaken, no CropARM data was available for Tasmania and no sites in CropARM allowed users to compare rainfed and irrigated wheat crops. This study collated data from 27 plots across ten sites in Tasmania, from the period 1981 to 2011, under both rainfed and irrigated conditions. APSIM was parameterised with these field observations and the subsequent scenario simulations were used to populate CropARM. Wheat cultivars used in the parameterisation of APSIM include Brennan, Isis, Mackeller, Revenue, Tennant (winter types) and Kellalac (spring type). The validation showed reliable model parameterisation, with an r 2 value of close to 1, which is considered satisfactory. 670,680 simulations were undertaken and incorporated within the CropARM database for wheat cropping systems across Tasmania. With regularly updated climate streams, the free online framework provided by CropARM gives users the ability to assess downside risks associated with several different crop management alternatives, and by simultaneously comparing multiple scenarios, users can select management options that are likely to adhere most closely with their desired management objectives.

Abstract. Although geographically small, Tasmania has a diverse range of regional climates that are affected by different synoptic influences. Consequently, changes in climate variables and climate-change impacts will likely vary in different regions of the state. This study aims to quantify the regional effects of projected climate change on the productivity of rainfed pastoral and wheat crop systems at five sites across Tasmania. Projected climate data for each site were obtained from the Climate Futures for Tasmania project (CFT). Six General Circulation Models were dynamically downscaled to~10-km grid cells using the CSIRO Conformal Cubic Atmospheric Model under the A2 emissions scenario for the period 1961-2100. Mean daily maximum and minimum temperatures at each site are projected to increase from a baseline period to 2085 (2071-2100) by 2.3-2.78C. Mean annual rainfall is projected to increase slightly at all sites. Impacts on pasture and wheat production were simulated for each site using the projected CFT climate data. Mean annual pasture yields are projected to increase from the baseline to 2085 largely due to an increase in spring pasture growth. However, summer growth of temperate pasture species may become limited by 2085 due to greater soil moisture deficits. Wheat yields are also projected to increase, particularly at sites presently temperature-limited. This study suggests that increased temperatures and elevated atmospheric CO 2 concentrations are likely to increase regional rainfed pasture and wheat production in the absence of any significant changes in rainfall patterns.

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