Calculating Yield Potential of Canola – Esperance Port Zone – by Ben Curtis
It has been a challenging start to the season. Rainfall has been very uneven across the Esperance port zone. In many cases, canola germination is also uneven. In some cases it is yet to germinate!
Quite a few people have asked me about the yield potential of canola for this year. Being a later start, it is difficult to guess what the canola yield will be, especially after five relatively good seasons. This will have an impact on your nitrogen decisions, as well as your outlook for profit this year.
Below is a graph produced by DPIRD from their APSIM model to help with your own calculations. For our purposes, Gibson, Ravensthorpe, Salmon Gums and Hyden are the most relevant locations. It basically demonstrates that sowing in the middle of April gives the highest yield potential in these three locations, as well as most other locations in WA.
To do a rough and ready yield calculation on individual farms, I have :
- Looked at individual farmer previous production history to determine their highest ever farm average yield for canola. I assume here that in the last five years, most growers would have approached their potential best yield.
- Established average germination date (not always easy this year).
- Found that date on the graph above and determined the percentage of maximum. For example, 30th May is 2.25 tonnes per hectare in Gibson, whereas 15th April is 2.75 tonnes per hectare. This equates to 2.25/2.75 *100 % = 81% of maximum yield potential in Gibson for 30th May germination.
- Therefore, if your best ever yield at Gibson was say 2 tonnes per hectare then with this later sowing date, you might predict 81% of this or 1.62 tonnes per hectare.
At Salmon Gums, for the same germination date yield potential is 60% of maximum. So if your best ever canola was 1.4 tonnes per hectare, then you might expect 800 kilograms per hectare with the later sowing date. The further inland you go the larger the penalties (on a percentage basis) for delayed sowing.
If you are located in Scaddan then you might split the difference between Gibson and Salmon Gums and work on approximately 70% of yield potential. Grass Patch, Cascade and Beaumont might be between 65% and 70% for these dates. For Ravensthorpe, the later germination penalty for end of May is approximately 70%.
Please contact myself (Ben Curtis) if you need a hand doing your own calculations.