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Tasmanian Institute of Agriculture

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The Tasmanian Institute of Agriculture has developed user-friendly online tools to help farmers make more informed crop management decisions about the effects of plant varieties, fertilisers, irrigation scheduling and sowing times on the growth, development and grain yield of important cereal crops in Tasmania.

Agricultural Production Systems SIMulator

Dual-purpose cropping decision-support tool

CropARM

Agricultural Production Systems SIMulator

The Agricultural Production Systems SIMulator (APSIM, http://www.apsim.info) is an existing biophysical model that uses information about key components of farming systems (e.g. climate, crops, water, pasture, trees, soil water, pH, erosion, etc.) to simulate what the economic and ecological outcomes of farm management decisions might be.

To provide greater benefit for Tasmanian farmers, TIA’s Water for Profit team has adapted APSIM to Tasmanian conditions. This work enables farmers to compare how different plant varieties, fertiliser application amounts, irrigation scheduling, and crop rotations perform with local soils and conditions in their specific region.

Three new studies using APSIM have been developed for Tasmania: dual-purpose cropping (DP), green peas, and winter wheat (CropARM).

If you have questions about these tools, please contact Dr Matthew Harrison (DP and CropARM) or David Phelan (Green Peas).

As with any decision-support tool, it is important for users to recognise that outputs (eg. grain yield) will not exactly reflect values measured on farm (eg. the actual harvest). This is because models are representations of reality that only include the main factors that influence crop growth - they do not include factors such as weeds, pests or diseases. The important point to remember when using such models is that they do not provide an absolute answer. Rather, they provide information that allows different options to be compared. For example, a farmer could use a model to answer questions like  “if I delay sowing for two weeks, am I likely to experience better or worse yield?”, or “does applying limited irrigation over the crop life-cycle result in a better yield outcome than only applying heavy irrigation in the window of flowering?”

Dual-purpose cropping decision-support tool

In collaboration with CSIRO and the GRDC, the Water for Profit team created an online tool that enables farmers to see how dual-purpose crops grow when grazed by different livestock under various stocking rates in Tasmania.

The decision-support tool shows how the yield of wheat and canola crops varies with alternative grazing durations and stocking rates of sheep or cattle. This information helps farmers make decisions about how their management options affect crop agronomy and potential economic returns.

With the dual-purpose (DP) cropping decision-support tool, users can choose location (eg. Cressy), crop and variety type (eg. long season winter wheat), sowing date (eg. 15 March), estimated flowering date (eg. 30 September) and target grain yield (eg. 6 tonnes per hectare). The DP tool then automatically estimates a median flowering date and an average yield. Providing details about the dates when grazing animals are removed from crops and their stocking rates provides information about the outcomes of different management decisions.

The Dual Purpose Cropping Tool is available at http://www.grainandgraze3.com.au

Green pea simulations

This work conducted simulations for farmers to assess how green peas will grow at four locations in Tasmania, under various sowing dates, irrigation and fertiliser regimes.

The simulations demonstrate how the yield of green pea crops varies depending on different conditions. For example, they can be used to infer potential year-to-year variability in yields as well as effects of rainfall and temperature on crop life cycles, including crop biomass, protein levels, flowering times, days to harvest and water use efficiency.

CropARM

CropARM is a simple software tool that compares the long-term risk of different agronomic management options.

The Water for Profit team calibrated APSIM with experimental yield and total biomass data measured for rain-fed and irrigated wheat crops, and then used the software tool CropARM at ten different sites in Tasmania.

Simulations used 115 years of climate records at each site to predict year-to-year variability. The management factors that can be examined include:

  • Crop type
  • Stored soil water at planting
  • Sowing date
  • Maturity length
  • Plant population
  • Row configuration
  • Soil nitrogen content at sowing
  • Nitrogen fertiliser rate (applied at sowing and/or within crop)

Each factor contains three to six levels from which users can select (.g. nitrogen applications at sowing include 0, 50 or 100 kg N/ha). CropARM has approximately 20 output options, including crop yield, water use, days to harvest as well as temperature stress indicators (e.g. frost/low temperatures around flowering). It also includes a simple gross margin calculator.

CropARM is available at http://www.armonline.com.au/#/wc

The full report about decision support tools and modelling work (including potato simulations) undertaken for the Water for Project project is available here.