This column was originally published in Prairie Farmer during the month indicated and is reprinted here by permission.

For an archive of all our Prairie Farmer columns click here.

Prairie Farmer - August 2007

Estimate Yield Without Guesswork

Garrett Stoerger
Department of Agricultural and Consumer Economics
University of Illinois at Urbana-Champaign

Can you tell me what your corn and soybean yield will be this year? Can you base your assumption only off of last year's yields, or even the past five years? Despite an overabundance of variables, farmers do their best to estimate yield in order to create yearly crop budgets, develop a marketing plan and make crop insurance decisions.

If calculating the standard deviation, slope and intercept is your idea of a good time, read no further. Our model has removed that “fun” from yield estimation. However, if you would like an easy-to-use model that will figure that out for you, you're at the right place.

The Yield Risk Evaluator tools are a series of FAST spreadsheets, one of many FAST tools available for free at www.farmdoc.uiuc.edu/fasttools.

If you have used the yield analysis tools from the University of Illinois ' Estimate yield without guesswork farmdoc Web site before, rest assured that the new look and feel will impress you. We've made this tool much more user friendly, with a completely redesigned menu and updated yield information.

Currently, the Yield Risk Evaluator can calculate the expected yield for every county in Illinois , Indiana and Iowa . Historical county data spans from 1972 to present for both corn and soybeans. In the near future, this tool will have the capability to analyze the historical yields from your actual farm.

Viewing ease

The best part about this tool is its ability to cater to you, the user. If you are someone who needs actual numbers to interpret the data, you can view and print the data in table form. On the other hand, if you are a more visual person who prefers looking at graphs, you can get that, too.

Yield and probability levels are required on one side of the model to complete the analysis. Providing the tool a set of limits will calculate the probability that yields will fall below the given level. Conversely, you can also change probability to reflect a given yield.

The opposite side of the model presents the data in two forms: a historical scatter plot with trend line and an interactive yield distribution curve. As displayed below, this interactive yield distribution curve allows users to position two scroll toolbars in different configurations to set an upper and lower limit. The resulting data will give the probability that yield will fall between the two defined limits.

If you have ever searched for the rational behind your yield estimates and are left scratching your head, this tool is certainly for you. Not only will you be able to draw conclusions for budgets and marketing, but this is an excellent way to represent yield data when trying to decide between alternative forms of crop insurance.

Stoerger is FAST coordinator with University of Illinois Extension.