Combine Yield Monitors, A Wonderful Tool, But.....

R.L. (Bob) Nielsen , Agronomy Department , Purdue University, West Lafayette, IN 47907-1150

Originally published in Purdue Pest Management & Crop Production Newsletter (5/5/95)

These fancy new-fangled combine yield monitors have monopolized the conversations up at the Hillside Cafe all winter. While most any on-the-ball corn grower can 'sense' yield differences across a field on-the-go by just paying attention to the operation of the combine, these high-tech yield monitors now offer the opportunity to actually watch those bushels per acre flash across an LCD display in the cab. With a little more investment, the grower can also 'download' that information to a personal computer, further massage it with intricate software, and eventually torture it long enough that it confesses.

THE BIG QUESTION IS: Just what do you do with all that data that's occupying valuable hard drive space on your computer? What do you make of the fact that grain yield varies 100 bushels per acre from one site to the next in your field?

Variable yield data alone tells you little if anything about the cause of the variability. Many, many factors influence corn grain yield, usually in combination with each other. Two sites in a field with identical low yields may result from entirely different combinations of factors. Unless you couple yield monitoring with season-long crop monitoring, you will be faced with trying to conduct post-mortem diagnoses of the causes of the yield variability across the field. Such post-mortem crop problem diagnoses are daunting, even for the professional diagnostician.

SO, A WORD TO THE WISE. To justify the investment in site-specific yield monitoring equipment, please also invest some resources in walking your fields, looking for crop problems, diagnosing causes of crop problems while the evidence is still visible, and keeping site-specific crop records (even if you have to use a primitive pencil and notepad). If you don't have the time (nor a willing family member) to watch the crops during the season, seriously consider using a 'hired gun' to do the work for you. Well-trained, professional crop consultants can help gather the necessary information in your fields throughout the season.