Wheat / mungbean opportunity cropping

In this exercise you will use sowing rules to opportunistically plant mungbean and wheat crops over a 10 year period without resetting water or nitrogen at sowing. You will observe the effect of this rotation on soil biomass nitrogen and the response of the rotation to different sowing rules.

The examples assume you have read and walked through the previous document: How to Build, Run and Graph a Simulation

  1. Start a fresh simulation using Continuous Wheat Simulation as a template
  2. Choose the Goondiwindi weather 1/4/1974 - 30/4/1984
  3. Select the "Grey Vertosol-Merwood (Croppa Creek No068)" soil (Soils->Australia->New South Wales->North West Slopes and Plains) and rename it to Vertosol

    4. This soil doesn't have crop lower limits for mungbean, so add a new crop to the soil. Make sure you call it mungbean. For this exercise, instead of changing LL, PAWC, KL and XF values just leave the default values. If you do not know how to add a new crop see the following document: How to: Adding crop properties to a soil .

  4. Set the Starting water to 50% full - filled from top.
  5. Set the Starting nitrogen to 140 kg/ha NO3  and 0 kg/ha NH4
  6. Add mungbean to the simulation tree, leaving wheat alone.
  7. Replace the Sowing rule with the Sow using a variable rule from the toolbox and rename to Wheat sowing - Janz.
  8. Set the properties of wheat sowing to:

    sowing window start date: 1-Jun
    sowing window end date: 14-Jun
    must sow: no
    amount of rainfall: 15
    number of days of rainfall: 3
    amount of soil water in profile: 200
    crop: wheat
    sowing density: 100
    sowing depth: 50
    cultivar: Janz
    crop growth class: plant
    row spacing: 250

  9. We want to sow an earlier maturing cultivar if the sowing is later so make a copy of this rule but change the window to 15-jun to 1-aug and the cultivar to hartog. Rename this new rule to Wheat sowing - Hartog
  10. Rename the harvesting rule to Wheat harvesting - make sure it points to wheat.
  11. Rename the Sowing fertiliser rule to Wheat sowing fertiliser. Make sure it points to wheat and set the amount to 70kg/ha of urea_n.
  12. Duplicate one of the wheat sowing rules and rename it to Mungbean sowing. Set the parameters to:

    sowing window start date: 1-Dec
    sowing window end date: 15-Jan
    must sow: no
    amount of rainfall: 20
    number of days of rainfall: 3
    amount of soil water in profile: 200
    crop: mungbean
    sowing density: 36
    sowing depth: 50
    cultivar: Berken
    crop growth class: plant
    row spacing: 500

  13. Duplicate the Wheat harvesting rule and rename to Mungbean harvesting. Make sure it points to mungbean, not wheat.
  14. Choose these variables to report:
    Component Variable name
    Global Year
    Soil (we renamed it to Vertosol) BIOM_N - layered.
    Mungbean or Wheat yield (this will output the yield for all the crops in the simulation. Mungbean yields and Wheat yields will BOTH be outputed in different columns)
  15. Choose a reporting frequency of harvesting.
  16. Rename simulation to Mungbean-Wheat. Save the filename to the same name.
  17. Make a copy of the simulation, setting the mungbean sowing window to 1-nov to 1-jan.
  18. Rename this simulation to Mungbean-Wheat Early.
  19. Run simulations.
  20. Create separate graphs of Year vs Mungbean Yield and Wheat Yield for each simulation. Drag an XY Chart on each simulation. (nb. You will get a DBNull error when you click on the graph component. Just click OK, and change the Y axis to "mungbean.yield" and "wheat.yield", then change the X axis to "year").
  21. Add Titles to each graph identifying them as Mungbean-Wheat and Mungbean-Wheat Early. To find out how to add a title to a graph see How To: Modify a Graph component

 

Question: Why is there no wheat yield in 1984?