Submitted to: Site Specific Management for Agricultural Systems Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/1994
Publication Date: N/A
Citation: N/A Interpretive Summary: Devices to monitor yield are available for grain crops, but none exist for potato or other bulky crops. Because the value per acre of potato is much higher than that for grain crops, potato growers are more likely to quickly adopt yield monitoring as part of an overall management strategy. This paper describes development of a potato yield mapping system that continuously records the weight of potatoes passing over a weighing conveyer on the harvester. These data were processed by a blocking program to create a yield map. Yield measurement accuracy for both a 1-row plot harvester and a 2-row commercial harvester was within 5%. Commercialization of this conveyor weighing technology is being pursued by HarvestMaster Inc., an instrument manufacturing company, for potato, as well as for other harvester systems that use conveyors to transport the product, such as those for sugar beet, onion, and wine grapes. Ultimately the development of yield mapping technology will lead to guidelines for site-specific placement of water, fertilizers and pesticides that meet, but do not exceed, the crop requirements of each part of the field. Site-specific management will make it possible for growers to both increase profits and decrease leaching of chemicals by reducing inputs.
Technical Abstract: The goal of the research supporting the development of this technology includes the integration of scientific knowledge into decision-support packages for farm managers. Prescriptions for site-specific inputs for each square meter of a field are essential to attain this objective. Real-time yield mapping is especially important in developing these prescriptions because yield is the most important spatial variable. Yield mapping technology is available for seed crops, but not for bulky products such as potato. This paper describes development of potato yield mapping technology at two scales: one for a 1-row experimental harvester as part of an integrated agriculture experimental program at Prosser, WA; the other for a commercial machine operated by Hess Farms Inc. at Ashton, ID, which harvested 10 rows in a single pass. In both cases the weight of potatoes per unit time was recorded continuously over a weighing section of the potato conveyor. Distance traveled per unit time was also recorded from magnetic switches on the harvester wheel. Dividing these two values gave potato weight per unit distance. Yield per unit area was obtained by multiply by the width of the rows harvested. The position along the row where yield was measured differed from that where the potatoes grew by a factor depending upon the travel speed and length of the harvester conveyor chains, requiring the use of a correction factor. These corrected point yield data were processed by a blocking program to create a continuous map layer in a geographical information system. Accuracy of measurements for both systems were within 5%.