Canola growers can lose up to 5 bushels or more per acre if the combine isn’t adjusted properly. Here are tips to limit those losses.
This pan connects to the underside of the combine and can be dropped with a switch in the cab. It covers the full width of the chaff discharge. Pans on sticks can work, too.
Step 1. Measure losses
Electronic loss monitors give you an idea whether losses are going up, but may not accurately tell you how many bushels per acre are thrown over. To calibrate loss monitors and to measure true losses out the back of the combine require a drop pan. Click here for an article with more detail on drop pan options.
How to take a sample
1. Disengage the chaff spreader and straw chopper and move them out of the way. That way, all straw and chaff drops straight down over the pan. This is important for calculations. Also, with the spreader off, the person holding the pan isn’t pelted with straw and seeds and dust if using a throw or stick pan.
2. Drop the pan, throw the pan, or hold the pan. When using the stick pan, the ideal is to move the pan into position upside down so it doesn’t gather any losses ahead of time. To position the pan, walk behind and to the side of the rear wheels and extend the pan so it’s in front of the chaff and straw discharge area. Once the pan is in position, quickly flip it over and stop walking. Stand still until the combine passes over the pan. With this procedure, you get the same result as though you’ve dropped or thrown the pan on the ground, but the handle gives you far more precision when it comes to placement. A long handle helps keep you out of the dust.
3. Remove the straw and chaff and preserve only the seed. A screen works. Another method is to put the collected sample in the bottom of a deep pail and stick a blower or old hairdryer into the pail. Chaff and straw will blow out and leave the seed behind.
How to calculate loss per acre
1. Measure the seed in the pan, by weight or volume. You need a scale that can measure in increments of 0.1 of a gram. You can also use volume or make a visual estimate. For more on these options, click here for a link to the Combine Seed Loss Guide.
2. Calculate based on one square foot. If your pan is two square feet, for example, divide the weight by 2 to get the total for one square foot.
3. Determine the concentration factor for your combine. This is a ratio of header or swather width and combine discharge width. For example, if the swather is 30 feet and the discharge width is five feet, then the CF is “6.” See the table to the right to calculate your CF.
4. Plug these numbers into the Weighing Method table below to get losses in terms of pounds per acre. For example, if the loss per square foot (cleaned) amounts to 6.2 grams and the combine CF is 6, this converts to a loss of 100 pounds per acre — or two bushels per acre.
5. Take another sample before moving on to steps 2 and 3.
Step 2. Determine whether those losses are acceptable
Combines running efficiently will lose some grain. If your target is zero losses, you’ll probably end up running too slow to get the job done in a timely fashion, risking shattering losses and cost increases that will outweigh any reduction in grain loss.
With canola, a three to five bushel/acre loss is fairly common. On a 40 bushel/acre canola crop, a three to five bushel loss represents 7.5% to 12.5% of the potential yield. Reducing those losses can provide a significant boost in profit. A properly adjusted combine going at a reasonable ground speed should be able to achieve a 0.5 to one bushel/acre loss.
Step 3. Steps to reduce loss
Check for leaks. Losses do not always come out the back end. Before making any adjustment to cylinder speed, concave spacing, fan speed or sieve spacing, check over the combine to make sure you don’t have any leaks. Look for holes and cracks on the pickup, feederhouse, elevator, shoe seals, separator covers and the grain tank. “You’ll be surprised how much canola can go through a bolt hole,” Hill says.
Feed the combine properly. Rotaries work best with a narrow windrow. Conventional walker combines work best with a wider swath that creates an even matt over the full width of the cylinder and walkers. A smooth rate of flow into the combine is also important.
Slow down. It may take just a small decrease in speed — say 0.2 or 0.3 mph — to provide a significant reduction in losses. The loss curve tends to remain fairly flat until ground speed reaches a critical point when combine capacity is taxed, then the loss curve can rise steeply.
Make adjustments. Check the combine operators’ manual and look at the range of settings for canola. Are you within those ranges? If not, try that first. Try one variable at a time and check losses between each adjustment. Check that the automatic settings on newer combines are calibrated. For example, if the chaffer setting on the monitor says 18mm, take a ruler and check that the chaffer spacing is in fact 18mm.
When considering adjustments, here are a few specific situations and possible solutions:
—If you find unthreshed pods in the chaff, the combine is underthreshing. Increase cylinder or rotor speed, narrow the concave setting, add concave blanks, or slow down.
—Losses can also result from going TOO slow. If straw is getting pulverized into small pieces that drop down to the sieves, thus reducing air flow and separation, this is usually a result of overthreshing. Cracked seed is another sign of overthreshing. Consider lowering the cylinder speed or widening the concave setting. This adjustment may also make it possible to drive faster and keep losses constant.
—For more of these scenarios, please read the Combine Seed Loss Guide.
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