While you can’t control the hot, dry weather conditions that affect rapid corn grain drydown, you can reduce the risk of yield loss during corn harvest.
As grain dries below 20% and grows brittle, the chances of yield loss from lodging, insect damage and other problems increases.¹ High heat and wind can lead to well over 1.0 percentage point of moisture loss per day in drydown.² Optimal moisture and equipment adjustments at harvest are critical to reducing yield loss.
3 tips to reduce corn harvest loss
Evaluating weather conditions and making mid-harvest adjustments can reduce corn harvest losses.
1. Plan your harvest priorities based on weather conditions
Should you harvest soybean or corn acres first? Look at the weather. If conditions leading up to harvest are excessively dry, yield loss will be more costly to soybean than corn. Corn can typically wait longer than soybeans.
2. Use corn harvest loss estimates to determine where the loss is occurring
Calculating harvest losses and making necessary adjustments early into harvest can significantly reduce yield loss. Both the header and the thresher can be responsible for corn harvest loss.
A simple way to measure kernel losses is to make a rectangular frame that marks off 10 square feet, place it over harvested sections, and count the left-behind kernels within the frame. Every 20 kernels of corn found in the frame represents the loss of about one bushel per acre.³
If ear losses are significant, this could point to a pre-harvest loss caused by disease, insects and/or inclement weather, so it is recommended to check for ears dropped from the stalk before harvesting. Pre-harvest checks can help you determine if losses are occurring from damaged ears or mechanical error.
3. Check the header and thresher for grain loss problems
Adjustments to prevent harvest loss at the corn header
On average, 66% of all machine harvest loss in corn occurs at the header.⁴
Overall, reducing header speed and relative ground speed can help minimize header loss. Here are two other adjustments to be conscious of:
- Width of deck plates: Setting deck plates too wide can cause excessive butt shelling of the ears. If deck plates are too narrow, coarse or damp stalks can get jammed. Ideally, aim for spacing between the plates that measures between ⅛” and 3/16” tighter at the front of the plates than at the rear. Since crop conditions are variable, closely monitoring deck plate spacing as you go can minimize loss and pay large dividends.
- Gathering chain speed: When changing ground speeds, be mindful that header loss will increase if the gathering chains and stalk roll speeds do not match the new ground speed setting. Generally, ground speed should be 4 mph and gathering chains should be running at 55 rpm. Ensure that ratio remains constant across all ground speeds.
Thresher adjustments to prevent grain loss
Threshing losses occur when kernels fail to break free of the cob as it passes between the cylinder or rotor and the concave. The following steps can help alleviate threshing losses.
- Reduce cylinder or rotor speed so an occasional kernel is left on the cob: Rapid cylinder or rotor speed can damage grain quality by introducing foreign material. Error on the side of caution and leave some unshelled grain on the cob, which can help prevent excessive kernel damage.
- Set thresher concave clearance so cobs fracture into halves or pie-shaped segments: Ideal clearance is narrow enough to thresh out the grain without being so narrow as to increase grain damage. In general, drier corn is easier to thresh, so this provides you with some leeway to adjust to a less aggressive setting without compromising efficiency.⁵
Experts are available to help you make your decisions and understand your specific needs. Reach out to a nearby extension office agent or a professional like your regional BASF representative.
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Endnotes
- “Grain Harvesting.” Wisconsin Corn Agronomy, March 14 2016, corn.agronomy.wisc.edu/Management/L032.aspx. Accessed 4 September 2026.
- Jackson-Ziems, Tamra, et al. “Harvest 2025 Prep Guide: Minimize Losses in Disease-Stressed Corn.” CropWatch, University of Nebraska–Lincoln, 19 Sept. 2025, cropwatch.unl.edu/harvest-2025-prep-guide-minimize-losses-disease-stressed-corn/. Accessed 4 Sept. 2026.
- Hanna, Mark. “Profitable Corn Harvesting.” Extension | Iowa State University Extension Store and Outreach, Iowa State University, shop.iastate.edu/extension/farm-environment/crops-and-soils/agronomic-crops/pm574.html. Accessed 4 Sept. 2026.
- Hartschuh, Jason, and Elizabeth Hawkins. “Minimizing Corn Harvest Losses At The Combine.” Agronomic Crops Network, 2021, agcrops.osu.edu/newsletter/corn-newsletter/2021-33/minimizing-corn-harvest-losses-combine. Accessed 4 September 2026.
- Arora, Kapil, et al. “Tips for 2023 Harvest: Handling Grain when Moisture is Low and Variability is High.” Integrated Crop Management, 25 Sept. 2023, crops.extension.iastate.edu/cropnews/2023/09/tips-2023-harvest-handling-grain-when-moisture-low-and-variability-high. Accessed 4 September 2026.
