Wheat / mungbean opportunity cropping

Exercise 6: 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. Rename simulation to MungbeanWheat. Save the filename to the same name.
3. Choose the Goondiwindi weather 1/4/1974 - 30/4/1984
4. Select the "Grey Vertosol-Merwood (Croppa Creek No068)" soil (Soils->Australia->New South Wales->North West Slopes and Plains) and rename it to Vertosol

   This soil doesn't have crop lower limits for mungbean, so you will need to add these new crop properties to the soil.
   For this exercise, set LL, PAWC, KL and XF values to the following:
   
   
   
   Make sure you call the node mungbean.
   
   To find out how to add a new crop to a soil see the following document in this manual (See contents page):
   How to: Adding crop properties to a soil .

5. Set the Starting water to 50% full - filled from top.
6. Set the Starting nitrogen to 140 kg/ha NO₃ and 0 kg/ha NH₄, evenly distributed.
7. Add mungbean to the simulation tree, leaving wheat alone.
8. Replace the Sowing rule with the Sow using a variable rule from the toolbox and rename to Wheat sowing - Janz.
9. 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
   

10. 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
11. Rename the harvesting rule to Wheat harvesting - make sure it points to wheat.
12. 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.
13. 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
    

14. Duplicate the Wheat harvesting rule and rename to Mungbean harvesting. Make sure it points to mungbean, not wheat.
15. Choose these variables to report:

    Component	Variable name
    Clock	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)

16. Choose a reporting frequency of harvesting.
17. Create a linked copy of this simulation via drag and drop and rename this new one to MungbeanWheat Early (to find out how to do this see: How To: Use linking to reduce simulation duplication)
18. Unlink the mungbean sowing rule and change sowing window to 1-nov to 1-jan.
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.
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



22. You will notice that your graphs do NOT match the graphs below. In order to make them match the graphs below you need to go back to the Wheat sowing - Hartog rule and change the "Amount of rainfall" to 30 and the "sowing depth" to 30. Because the simulations are linked you only need to make this modification to the Wheat sowing - Hartog rule in one of the simulations. The Wheat sowing - Hartog rule in the other simulation is automatically changed as well. This is the benefit of using linked simulations.



23. Run the simulations again and now compare the graphs to the graphs below.

Question: Why is there no wheat yield in 1984?