Precision Agriculture, 4, 433±444, 2003
2003 Kluwer Academic Publishers. Manufactured in The Netherlands.
Sugarbeet Yield Monitoring for Site-Specific
Farming Part IIÐField Testing
T. L. HALL, L. F. BACKER AND V. L. HOFMAN Leslie.Backer@ndsu.nodak.edu
Department of Agricultural and Biosystems Engineering, North Dakota State University,
Fargo, ND 58105
L. J. SMITH
University of Minnesota-Crookston Northwest Experiment Station, Crookston, MN 56716
Abstract. A field studywas conducted to evaluate three real-time weighing systems to measure sugarbeet
yield. Two systems permit use of the storage hopper onboard the harvester. The effects of tare on yield
measurement were investigated. Parallel yield data from the three systems were compared. There was a strong
relationship between systems as sugarbeet flow rates changed. High standard deviations were found for all
product flow sensors. There was no statistical difference between two of the sensors, but there was for the other.
One system provided unacceptable results. One of the systems provided reasonable accuracy and permitted use
of the onboard storage hopper.
Keywords: sugarbeet yields, site-specific farming, sugarbeet harvesting, yield monitoring
Limited research has been directed toward root crop (i.e. potato, sugarbeet, etc.) yield
monitoring (Campbell et al., 1994; Hofman et al., 1995; Rawlins et al., 1995; Walter
et al., 1996) but results have shown the potential to accuratelyand preciselydetermine
site-specific yield information (Hall, 1998). Some of this research resulted in the
development of the HarvestMaster
(HarvestMaster, Inc., Logan, UT) yield
monitor. However, the effects of tare on accuracyand precision are a concern.
A typical yield monitor has load cells mounted near the end of the outlet conveyor. An
advantage of this location is that the maximum amount of tare is removed from the
sugarbeets before their weight is assessed. Research was conducted to determine the
effect of chain support systems on sugarbeet yield monitor accuracy and precision. When
product flow sensors were mounted on a short conveyor section, sugarbeets tended to
bounce on the conveyor resulting in lower accuracy and precision. Reducing the length of
the chain support system minimized the effects of the bouncing sugarbeets (Hall et al.,
The storage hopper on manyharvesters can not be used if accurate site-specific yield
data are to be collected using a yield monitor on the outlet conveyor. The reason is that
the load cells are located in the product flow stream beyond the storage hopper.
Therefore, if the hopper is used, position data relative to yield are lost. Sugarbeets could
be weighed before being loaded into the hopper to overcome this problem. However, the