Yield mapping also allows better on-farming testing than simply using a limited number of measurements with a weigh wagon. When used as intended, yield monitors provide a good estimate of the grain yields. Be sure to calibrate using several high and low flow rates. Grain moisture, flow rate, field slope, operating capacity and even a weed patch can lead to variations in data. If the yield map appears to have strips, don't rush to blame the fertilizer dealer.
Wheel slippage can give the monitor false information.
In fact, research shows that every one percent slope can result in a one percent error in yield monitor accuracy. Of course, combines that use radar to determine speed rather than wheel rotation also solve this issue. Just like with planting equipment, calibration is critical to obtaining accurate readings from yield monitors. To reduce the margin of error, yield monitors should be calibrated at three operating capacity levels . . . A point of clarification, 'low flow' means more than a trickle.