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Estimating Seed Loss

Saturday, August 14, 2021
filed under: Harvest/Storage

harvesting fieldDo your seed loss levels during sunflower harvest typically fall within the “acceptable” or “excessive” range? Losing 10 (filled) seeds per square foot represents about 100 lbs/ac, assuming that loss level is consistent across the field.
It’s virtually impossible to avoid some seed loss during harvest, of course. Traditionally, 3% has been considered an “acceptable” loss level. But harvesting abnormally dry seeds — such as may well turn out to be the case for numerous producers in 2021 — can drive up that number. So too can excessive ground speed or a combine that has not been set and/or adjusted properly.
Here’s an easy way to estimate sunflower seed loss during harvest, as provided by North Dakota State University ag engineers:
  1. Count the number of seeds within a one-square-foot area ahead of the combine at several different sites within the field.
  2. Calculate header loss by counting the seeds within a square-foot area behind the head and beneath the combine. Then subtract the “standing crop” loss.
  3. The loss in combine separation can be determined by counting the seeds within a one-square-foot area directly behind the rear of the combine. Subtract from that the shatter loss and the header loss.
  4. The count from directly behind the combine will be concentrated, so an adjustment must be made to equalize the loss across the entire width of the cut. The result should be divided by this ratio:  Width of Header Cut (feet) divided by Width of Rear of Combine (feet).  See image of formula below.
  5. The result — i.e., the adjusted separator loss for the width of cut — must then be divided by 10 to determine the combine separator loss in hundredweight per acre.
  6. Total loss (cwt/ac) is arrived at by adding up the seed loss in the standing crop, the header loss, the separator loss — and then dividing that number by 10. The percentage of loss can be determined by dividing the total cwt/ac by the field’s final sunflower seed yield.
seed loss formula

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