How to calculate harvest losses
October 25, 2002
Follow these four steps to arrive at an estimate of harvest losses:
Locate three random sites in the field At each site, outline an area that is 1 ft. in the direction of equipment travel and is as wide as the effective width of the implement. For example, if a combine is picking up windrows containing 12 30-inch rows, the width of the measurement area should be 30 feet. Examine the entire width of the implement pass, not just behind the threshing section of the combine where loss can be concentrated.
Search the soil surface and through any soil loosened by harvest implements within the outlined area for seeds and unthreshed pods. Count all bean seeds.
Divide the number of seeds found by the number of square feet within the outlined area. This will provide the average number of bean seeds lost per square foot. Take an average of the three areas sampled within the field.
Use Table 1 to convert average number of seeds lost per square foot to pounds of seed lost per acre for specific seed sizes. If a sampled area over the full effective width of an implement pass averaged 1 pinto bean seed per square foot, the field loss would be approximately 36 lb/A, assuming 1,200 seeds/lb. To extrapolate to 3 seeds/ sq. ft. for the same seed size of 1200 seeds/lb, one could multiply 3 by 1.0 by 36 lb/acre = 108 lb/acre field loss.
Average number of seeds lost per square foot
pounds/acre field loss
Seeds per pound
||Seeds per pound|
--Source: NDSU Extension Service