Maximizing Grain Harvest Profitability
Matt Darr
 
Several key factors are often attributed to yield losses during a growing season including poor weather, insufficient weed control, and disease.  As producers, you can only manage these factors to a limited extent.  On the other hand, properly maintaining and adjusting your combine is easily controlled and can make a dramatic impact on your overall yield.  Although grain losses during harvesting can never be totally eliminated, several steps should be taken to minimize the losses.

Did you know that every 20 kernels of corn you find within a given 10 square feet section of your field will equate to approximately 1 bushel of losses per acre?  University studies have shown that around 6 bushels per acre are lost during harvesting, while the top 10% of combine operators can reduce this to around 1.5.  How much of an impact does this make to your bottom line?  Given today’s grain market, a producer operating with an average loss of 6 bushels per acre can look to profit an additional $11.00 per acre if the time is taken to properly adjust the combine.

Where Do Harvest Losses Occur?
Preharvest losses occur when the grain falls from the stalk before harvest.  This can be significantly impacted by hybrid selection, harvest timeliness, and weather patterns near harvest.  Although these losses are not caused by the combine itself, they can be minimized by harvesting earlier and considering ear loss in hybrid selections.  The yield benefit of harvesting earlier must be compared to additional drying costs to determine if this is a profitable decision.  Gathering losses occur at the interface of the combine and the crop and can have several different causes.  These losses can be in the form of whole ears not being gathered by the head or individual kernels being knocked loose by an overaggressive head.

Harvest losses also occur after the grain has entered the combine.  Threshing losses occur when kernels are not properly removed from the cob or pod.  Threshing losses can be easily spotted behind a combine as cobs with kernels still intact.  Separator losses occur when grain is properly threshed from the cob or pod, but is then not properly separated from the excess plant material.  Separator losses are identified as individual kernels found behind the rear of the combine. 

Minimizing Losses
The main avenue to minimize harvest losses is to ensure your combine is well maintained and in good repair.  All chains should be properly lubricated and tightened.  Belts should not show any signs of wear and bearings should be properly lubricated.  Also, always operate the combine at the ideal engine speed as set by the manufacturer.  These basic maintenance steps will keep the combine operating at peak efficiency and reduce harvest losses. 

Snapping rollers should be set closer at the front of the head to prevent wedging of stalks and reduce gathering losses.  Typically, a  1¼ inch spacing at the front and 1 3/8 inch spacing in the rear is adequate.  Snapping roller speed should be adjusted so that the ear is detached approximately half way up the roller. 

Adjust cylinder-concave settings as specified by the manufacturer and adjust cylinder speed so that it is just high enough to adequately perform threshing.  Excessive cylinder speed can cause grain losses and an overall reduction in grain quality.  Proper cylinder-concave adjustments will reduce threshing losses.  Separator losses are reduced by properly adjusting the chaffer, sieve, and fan speeds. 

Avoid overloading or underloading the threshing system by adjusting ground speed to match the field conditions.  In high density, well yielding areas slow the combine to help regulate the material in the threshing system and reduce threshing losses.  In low density, low yielding field conditions increase the ground speed to increase material in the threshing system and reduce grain damage. 

Be prepared to spend time each day checking the performance of your combine.  Walk in front of and behind the combine to determine whether the losses are preharvest, gathering, threshing, or separating related.  When making adjustments, do so in small increments to gradually find your combine's “sweet spot”.  Remember, overadjustment or overtightening will cause excessive grain damage. 

Yield Monitors – Calibrate, Calibrate, Calibrate!
Yield monitors have greatly enhanced producers’ ability to quantify the variability of grain yields.  Although yield monitor technology continues to improve, they still require regular calibration throughout the harvest season.  

Visually inspect the yield sensor and moisture sensor to ensure they are free from obstructions and plant material buildup.  Also double check that the GPS antenna is securely mounted and that all cabling is properly installed. 

At a minimum, calibrate the yield monitor each time you switch crops, when the crop moisture changes substantially, after you make any adjustments to the clean grain elevator, or if the crop yield is significantly different from the past field. 

Remember, if you are using yield monitoring data to help make management recommendations, then your recommendations are only as good as your yield monitoring data.  If your yield monitor is poorly calibrated, then your yield results will not accurately reflect your field performance and you will not be able to make accurate management decisions for future years. 

For more information on yield monitor calibration, visit the OSU Precision Agricultural website at http://precisionag.osu.edu/resources/ymonitor.html

Matt Darr, Instructor and Research Associate, can be reached at 614-292-1406, or darr.27@osu.edu.