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Title: VERIFICATION OF THE YIELD MONITOR PERFORMANCE FOR ON-THE-GO MEASUREMENT OF YIELD BY COMPARISON WITH AN ELECTRONIC SCALE

Author
item AL-MAHASNEH, MAJDI - IOWA STATE UNIVERSITY
item Colvin, Thomas

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: A commercial combine equipped with a yield monitor and Differential Global Positioning System (DGPS) was modified to include a weighing system in the clean grain tank. The scale was able to output its current readings two times per second to a data-logger. The reading from the yield monitor and the scale could be matched to check the accuracy of the yield monitor summary as well as individual (one-second) readings. Tests were conducted in fall 1996 (corn), summer 1997 (oat), and fall 1997 (corn). The yield monitor matched the readings taken by the scale very well when whole loads were used for comparison and the yield monitor was asked to give the summary for the load. The yield monitor did not do as well when its individual second by second readings were compared to the individual readings taken with the scale. The agreement dropped from almost perfect to only matching about 75% of the time. When individual readings were summed, the agreement between the yield monitor and scale improved when longer distances were used (more readings were included in the summary). The agreement improved from about 75% when values were summed over 60 ft to 98% when summed over 300 ft. The impact of this work is that precision farming management will not be very reliable if it depends on individual one second readings from a yield monitor, but we have shown that lengths of 100 to 200 feet may provide reliable data for decision making by scientists and farmers.

Technical Abstract: A commercial combine equipped with a yield monitor and Differential Global Positioning System (DGPS) was modified to include a weighing system in the clean grain tank. The scale was able to output its current readings two times per second to a data-logger. The reading from the yield monitor and the scale could be matched to check the accuracy of the yield monitor summary as well as the individual (one-second) readings. Harvest data from three fields (Kelly farm, corn, fall 1996; Burke farm, oats, summer 1997; and AERC farm, corn, fall 1997) were collected using this system. Data from both the scale and yield monitor were analyzed to verify the accuracy of the yield monitor. The scale was verified to be accurate. The results showed that the yield monitor has two data processing streams: one gives the individual weights (one-second interval weights) and the other gives the summary weights (total load weights). The results showed that these two streams are slightly different. Further analysis was conducted to understand these differences. The results showed an increase in the yield monitor accuracy with the harvest strip length; furthermore, the data collected during the 1997 harvests (Burke farm and AERC farm) were found to be more accurate than the 1996 harvest (Kelly farm). It was concluded that the new yield monitor updated chip (version 6.02 CJC) that was installed after the 1996 harvest season was the primary reason for this improvement.