Harvest, The Many Decisions that get Left in the Dust

By Jill Martens

The mindset around harvest is often ‘get it in the bin’. This tends to accompany overlooked decisions such as combine speed of travel, direction of cutting, or recording data to analyze different trials performed throughout the growing season. Many think ‘I don’t want to slow down my operation in harvest since we never know when the next rain is coming’. This is all important information that is already being recorded in our combines, we just need to properly use this information to make informed decisions. 
The two decisions that stuck out in the harvest of 2018 were cutting direction on pulses and cutting speed in canola. As an agronomist, I have heard both perspectives pertaining to cutting direction:  ‘there is no way it would pay for me to cut one direction’ or ‘if I can get an extra bushel to the acre going one direction, why wouldn’t I?’ The most important thing is to know your costs and break down the benefit versus the cost. 

An example from one of our Field Verified Trials in lentil this season:

• Combining east to west on a 1.3 acre pass you get 33.9 bushels 
• Combining west to east on a 1.3 acre pass you get 30.2 bushels 

Initially, these results suggest an obvious decision to combine one direction because in one pass you have left behind 3.7 bushels. However, first we need to make comparisons using dollars per acre. So 3.7 bushels/1.3 acres at $10 bushel-1 is $28.46 ac-1 (on the acres harvested west to east). 
But what are we giving up in order to get that extra money?

• Adding time to your harvest, meaning if you are adding 38% more time to combine that field (Assuming combining at 4.5 mph and driving back at 12 mph).  According to the Alberta Machinery Cost Calculator a Class 7 combine operating and ownership cost is $400.98 hr-1. At this it costs an extra $16.54 ac-1 to combine one direction.
• This is not accounting for possible grade reduction on not only the field that you are combining slower but also the rest of the farm that is left out in the field for longer.  
• Leaving bushels in the field also means that those seeds are viable to become volunteers in the upcoming years. 2 bushel left behind = 2x most farmers seeding rate. 

At these costs the breakeven would be around 2 bu ac-1 on lentils (on the acres harvested west to east).
Combine Speed in Canola:

• If you find 1 extra bushel of canola per acre thrown over to go an extra 1 mph, does that mean you have given up $10 ac-1 on 2000 acres=$20,000? 
• Using yield maps or, drop pans you can measure your yield loss at different speeds and find the sweet spot.
• The canola thrown over becomes part of the weed seed bank. Volunteer Canola at 1 bu ac-1 is 9.6 X the seeding rate most farmers seed their canola at. This adds the cost of a tank mix partner for a pre-seed burn down as well as possible yield loss these volunteers will cause.

Opportunity costs come into play in this situation as well.

• Going 25% slower comes at a cost as well. 12.3 hours to combine 160ac at 3 mph – 9.4 hours to combine 160ac at 4 mph= an extra $7.24 ac-1 in combine cost.
• There is the opportunity cost of leaving the crop out for longer and harvest running later in the year as well. This will have to be calculated based off of what other crops are left out in the field, the possibility of down grading, and yield loss.

Figure 1. Climate/Field View Scree Shot showing a side-by-side of speed vs. yield.

The opportunity cost calculation can be used for many decisions and can be calculated on the go, or looking back during the winter to make decisions for next year. Such as herbicide, fungicide, different varieties or even different cutting speeds or directions. There are many technology companies that are trying to make these observations and decisions easier for the grower. One company that G-Mac’s  AgTeam has worked with during the 2018 harvest was Climate/Fieldview. This product has an application that can show a split screen of the same field outlining different characteristics, such as the yield vs altitude, or the yield vs speed (Figure 1). Cross referencing yield maps to different characteristics helps paint a more useful picture that can alter your crop plan/operations to result in the best return per acre.
If you would like help making some of these operational decisions on your farm, or if data as shown in the screen shot from Climate/Field View interests you and has a fit on your farm, stop by a G-Mac’s location and we would be more than happy to help you!