Browsing by Author "Sexton, J"

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    How much nitrogen will that crop need? Incorporating climate forecasting to improve nitrogen management in the Wet Tropics : Final project 2015/075
    (Sugar Research Australia Limited, 2018) Everingham, Y; Biggs, J; Schroeder, B; Skocaj, D; Thorburn, P; Sexton, J
    Determining the optimum amount of nitrogen that is required by the crop to maximise production, profitability and environmental outcomes is a challenging problem. The modelling approach taken in this project has balanced each of these complex elements to produce, and demonstrate, a novel and grower-friendly solution for the Tully canegrowing region. Optim-N Gets a Thumbs Up “How much nitrogen does my crop need?” depends on many interacting factors such as soil type, harvest management, position in the landscape and climate variability! This project took a unique and innovative approach to solving this problem and neatly embedded this process in a prototype tool called “Optim-N”. Instead of applying the same rate of nitrogen every year, Optim-N formulates nitrogen guidelines based on climate forecasts, for eight important soils in two climate zones in the Tully region, and three harvest dates. The processes behind Optim-N were tested against all available data, both from experiments and, where these were not available, expert opinion. When fully developed and operational, this tool will save farmers money by tailoring season- and site-specific recommendations for individual cane paddocks; improve water quality leaving farms and entering waterways to the Great Barrier Reef, and skill-up extension officers, allowing them to provide more targeted advice for farmers that factors in seasonal climate forecasts from the world’s best climate models. Two major activities are needed to take Optim-N from a prototype, to a widely used tool: Optim-N would need to be trialled with farmers in an action learning context so they could understand how it helps their decision making. This experience would also drive refinements of the Optim-N tool. It would also provide more empirical data for testing the science behind the tool, reducing the reliance on expert opinion and simultaneously increase trust and end-user confidence in the tool, which would accelerate adoption. The Optim-N prototype also needs input from professional software experts to take it to commercial levels of robustness and usability. When presented at a variety of forums, the Optim-N prototype receives a big “thumbs-up”.
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    Productivity performance of climatological sub-regions within the Tully Mill area : ASSCT peer-reviewed paper
    (ASSCT, 2019) Stringer, JK; Skocaj, DM; Rigby, A; Olayemi, M; Everingha, YL; Sexton, J
    Inter-annual climate variability has a significant impact on productivity in the Wet Tropics region. Climate also varies spatially, yet the impact on productivity is less well known. Two distinct climatological sub-regions (northern and southern) have been identified within the Tully mill area based on total annual rainfall and annual average daily radiation. The wetter northern sub-region is characterised by lower radiation, lower temperatures and higher rainfall than in the drier southern sub-region. Mean cane and sugar yields were analysed for the two climate sub-regions using block productivity data obtained from Tully Sugar Limited for 2000 to 2017. After excluding 2011 (Tropical Cyclone Yasi), only farms with 15 or more years of data were included. The impact of spring-summer (SONDJF) rainfall and El Niño Southern Oscillation (ENSO) phases on cane and sugar yields in the two climate sub-regions was also analysed. On average, the northern, wetter climate sub-region yielded less cane and sugar yield than the southern, drier sub-region. There were significant differences between SONDJF rainfall terciles (dry, normal and wet) and ENSO phases (El Niño, Neutral and La Niña) for cane and sugar yields in the two climate sub-regions. Cane and sugar yields were significantly lower in years experiencing high SONDJF rainfall or in the La Niña phase. This analysis validates the results of the analyses used to derive the two climatological sub-regions in Tully. Improved knowledge of how climatic conditions influence sub-regional productivity performance will assist industry extension programs and on-farm management decisions.