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Straight Stalk

2013 Corn and Soybean Yields

A few days ago, the National Agricultural Statistics Service (NASS) released the county corn and soybean production numbers. This annual event is often a source of bragging rights for which county had the highest corn and soybean yields. The top yielding corn county in 2013 was Carroll in northwestern Illinois with an average yield of 200 bushels per acre. For soybean, DeKalb took the honors with 58.4 bushels per acre.

More importantly this data is used by the ag industry for more serious purposes. County average yields can affect landowners and tenant farmers as they adjust cash rent levels. Many landlords and tenants use a modified cash rent that fluctuates up and down based on whether the county yields were up or down. These yields also play a role in many farm program and crop insurance decisions.

This year data for several counties was not released in the report. I called the Illinois NASS field office and was forwarded to the regional office. A nice guy in charge of the corn estimates explained that this happens when one of two things occurs. The first is when there are only one or two growers in a county and the numbers could be directly associated with an individual grower. NASS takes privacy very seriously. The second case is when there are too few reports from a county and when looked at statistically they fall below a certain level of confidence. If the sample size is too small or the numbers vary too much then the result runs the risk of not accurately reflecting what the real county average yield was.

In the center part of Illinois, Menard, DeWitt, Bond, Clark and Lawrence did not have reported corn estimates. However for soybeans, Clark and Lawrence did have estimates, but no data for the other three. "No data" is not quite correct, in the NASS crop reporting district summary there is an "Other Counties" listed for the districts with missing county estimates.

When the data is mapped out it gives a picture of where the combination of best soils and weather coincided in 2012. In general, the second tier of counties, not the ones on the Wisconsin border but the next ones south had very good yields this year. The Logan, Sangamon and Christian areas had top corn yields too. The full NASS report can be found here.

A larger version of the map is available: