Yield Monitor Calibration: Garbage In, Garbage Out

Grain yield monitors have been in vogue for more than 10 years and can provide valuable spatial yield information to growers. Yield monitors offer a visual diversion from the boredom of harvest. They provide a source of historical yield records more detailed than that offered by elevator weigh tickets. They provide a viable alternative to weigh wagons or farm scales for measuring yields in on-farm research trials. When connected to a DGPS receiver, yield monitors generate a source of geo-referenced yield data that can enable growers to document the extent of spatial yield variability within fields. Yield estimates on a whole field or individual load basis made by a well-calibrated yield monitor are accurate in the sense that they often very closely match yield estimates calculated from weigh wagons or commercial weigh scales. However, to achieve a satisfactory level of accuracy, yield monitors must be "trained" to correctly interpret the electrical signals generated by the impact sensor into estimates of grain flow rate. Some background information may help you better understand the nature of and importance of faithfully and regularly calibrating yield monitors.

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Dr. Robert (Bob) NielsenProfessor of Agronomy
Purdue University
rnielsen@purdue.edu

I am a Professor of Agronomy at Purdue University with major responsibilities for Extension education in corn management systems for the state of Indiana. Originally from Nebraska, I joined the Agronomy staff at Purdue in 1982 after obtaining M.S. and Ph.D. degrees from the University of Minnesota. I am actively involved with Purdue’s Crop Diagnostic Training Center, a hands-on educational facility located at the Purdue Agronomy Farm. One of my major Extension activities is the development and maintenance of Web-based corn information sites. My two most popular Web sites are the Corn Growers' Guidebook (http://www.kingcorn.org) and the Chat ‘n Chew Café (http://www.kingcorn.org/cafe). Recently completed field research includes the effects of uneven plant spacing on corn grain yield. My current field research involves investigations into the relationship between crop canopy reflectance and optimum nitrogen fertilizer rates in corn, the potential for arrested ear development in response to spray additives, and the productive utilization of site-specific crop management tools.