Author
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ARSLAN, SELCUK - IOWA STATE UNIVERSITY |
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Colvin, Thomas |
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Submitted to: Precision Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/22/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Farmers can use yield sensors that are mounted on combines to measure grain yield and then generate a yield map that shows the variations of grain yield in a particular field. This can help them make decisions to treat different parts of the field differently, which eventually optimizes the yield in different locations within the field. This study showed that yield sensors and grain mixing inside the combine would prevent generating accurate yield maps if one wanted to treat very small areas in a field. It was determined that more reliable yield maps can be obtained if the field is not divided into cells smaller than 50x15 ft for determining the yield level in each cell. The yield sensor used in this research was found to be a useful instrument that can show yield trends within a field provided that it is well calibrated. The results of this study could help farmers and agronomists determine smaller manageable areas in a field for better crop management. Technical Abstract: Various field experiments were conducted to determine the response of a yield sensor and a combine harvester. Grain yield measurement comparisons were made between an impact based yield sensor and an electronic scale in adjacent harvest strips. Yield measurements were more prone to errors as the segment lengths decreased. Grain yield difference between the yield sensor and scale ranged from 5 to 14%, 4 to 13%, 3 to 12%, and 2 to 11% fo 15, 30, 60, and 300 m long segments, respectively. The yield differences between neighboring segments might have been caused by yield variability to a degree; however, consistent decreases in yield differences with increasing segment lengths implied that better accuracies could be obtained in larger management areas. The combine's response to grain yield changes was evaluated by creating specific yield patterns in harvest strips. Grain diffusion within the combine was more obvious when abrupt yield changes were introduced at known locations. Grain mixing and redistribution insid the combine may dictate the selection of segment sizes in the site-specific decision making process. Grain flow rate values were more stable at a constant ground speed compared to varying ground speed. The average error was 3.4% and 5.2% at constant ground speed and varying speed, respectively. Careful calibration and constant combine speed were important to achieve better accuracy with the grain yield monitors. |
