SOI phase and Economic analysis

In this exercise, you will examine the effect of SOI phase on yield probability, and gross margin outcomes. Exercises will also be conducted using manual generation of a probability distribution and the application of economic principles.
 

  1. Create a new simulation using Continuous Wheat Simulation.
  2. Rename simulation to Wheat_SOI_s
  3. Choose Goondiwindi weather (long term 1940 to 1989)
  4. Starting date 01/01/1940 Ending date 31/12/1989
  5. Choose "Black Vertosol-Anchorfield (Brookstead No006)" soil. (remember to rename)
  6. Set the starting soil water to 33% full – filled from the top
  7. Use default initial soil nitrogen
  8. Set initial surface organic matter is sorghum and is 1500 kg/ha. (rename the pool name, but leave everything else)
  9. Modify sowing rule to:

    Force sowing to 10-Dec
    Enter sowing density at 5 pl/m2
    Cultivar as medium
    Skip row as soild
    (leave everything else as is)

  10. Set fertiliser at sowing to 100 kg/ha of urea_no3. (move this rule up so that it comes before harvesting rule)
  11. From the Standard toolbox drag in a "Yield moisture correction" and a "Simple gross margin (put before harvesting rule)" rule. (make sure the "Yield moisture correction" rule comes before the "Simple gross margin" which obviously comes before the harvest rule)
  12. Report year, yield and Bank in the output file. (Just type "Bank" in manually into the variable list)
  13. Create a linked copy of this simulation via drag and drop and rename this new one to Sorghum_SOI_skip (to find out how to do this see: How To: Use linking to reduce simulation duplication)
  14. Unlink the sowing rule and change it to double skip
  15. Run both simulations (check the simulations run error-free)
  16. Graph Yield of both simulations using an SOI Box Plot from the Graph toolbox. (There is an error in the "Phase filename" you need to change it so that it is %apsuite\Soi\phases.soi, we will fix this in the next release.)
  17. We want to look at the Yield in the Box Plot so tick "Yield" in the FieldNames
  18. Given we used a sowing date of December, use the SOI from November to split the years. ("Month" drop down list)
  19. Deselect all SOI phases except negative and positive Years
  20. You will notice that the labels on the X axis can not be read, so expand the width of the graph until they become readable (to find out how to do this see: How To: Modify a Graph component)

    21. The output demonstrates the differing probability distributions of solid vs double skip configuration in negative and positive SOI phases
     

  21. Compare with "SOI CDF" and "SOI Probability Exceedence" graphs. (If you notice that when you click on something else and click back on the graph it has disappeared, just tick the "Yield" in the FieldNames. This is another error that will be fixed in the next release)

Economic analysis

This simulation has two rules from the Standard toolbox that we dragged in. A "Yield moisture correction" and a "Simple gross margin" rule.

You also remember how you manually typed in Bank into the output variable list. To see where it comes from click on the "post" tab of the "Simple gross margin" rule.

You can create your own economic calculations by using these kind of manager rules.

Keep in mind though when using these rules, that yield in APSIM is calculated as dry yield. So this assumes no water content. Much economic analysis requires a wet yield which is what a farmer will actually harvest from his paddock. This is why in our simulations we used a "Yield moisture correction" to do a simple calculation to work out this wet yield. (see its "start_of_day" tab)

  1. Graph gross margin using the SOI graphs you have already created. (In FieldNames untick Yield, and tick Bank)
  2. Change the Y axis title to "Gross Margin".



    Note: Similar output can be obtained via the WhopperCropper program that allows selection of the required input variables from a pre-determined set (usually 3 to 6 options for each variable).

Further economic analysis in Excel

  1. Select the top component Simulations then click the Excel button on the top toolbar.
  2. You will notice that the output files have been exported to 2 separate Excel windows.


  3. *** At this point you can manipulate the data however you like in the EXCEL program ***