Harvest · August 2025 · 5 min read
Total harvest losses of 3–5% are common, but poorly adjusted equipment or rushed operations can push losses above 10%. Systematically identifying and reducing each source of loss puts more bushels in the bin and directly increases your revenue per acre.
Harvest losses fall into three categories: header losses from shatter, stalk roll shelling, or missed ears; threshing losses from unthreshed grain passing through the rotor; and cleaning losses from good grain blown over the sieves and out the back. Pre-harvest losses from lodging, dropped ears, and weather also contribute but occur before the combine enters the field. Each source requires different adjustments to correct.
Use a loss measurement frame (approximately 10 square feet) placed on the ground behind the combine to count loose kernels and unthreshed material. First measure pre-harvest loss ahead of the combine, then total loss behind it — the difference is machine loss. Repeat measurements in multiple locations across the field, since crop conditions and terrain vary and a single sample may not represent the whole field.
Address the largest source of loss first — if header losses dominate, adjust reel speed, header height, or gathering chain timing before touching the rotor. For threshing losses, increase rotor speed or decrease concave clearance incrementally. Cleaning losses respond to fan speed and sieve opening adjustments. Make one change at a time and remeasure so you can identify which adjustment had the greatest impact.
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