Recent bullishness in corn and soybean futures has been driven by a tightening balance sheet in both crops. Demand has expanded, and weather in key growing areas has trimmed supply. That weather is now showing up in the USDA crop condition ratings (USDA-NASS, 2026), and the Pro Farmer Crop Tour came in well below USDA on corn (Pro Farmer, 2026), which has set off a good deal of online debate about yield estimation.
August is the first WASDE of the year in which USDA revises yields using survey data rather than trend, and it is where the largest yield revisions of the season cluster (Gardner, 2026). Those revisions do not stop in August: since 2010, the final corn yield has differed from the August estimate by an average of 3.8 bushels, landing below it in 11 of 16 years, and soybeans have differed by 1.5 bushels. In the August WASDE (USDA-WAOB, 2026), USDA cut corn yield expectations by 2.3 bushels to 180.7 bushels per acre and soybean yields by 0.3 bushels to 52.7 bushels per acre.
Meanwhile, the Pro Farmer Crop Tour, which samples fields across Ohio, Indiana, Illinois, Iowa, Minnesota, Nebraska, and South Dakota, estimated corn at 173.2 bushels per acre and soybeans at 53.3 bushels per acre. That puts the Tour 7.5 bushels under USDA on corn and 0.6 bushels over USDA on soybeans. Those seven states account for roughly two-thirds of U.S. corn and soybean production, and the Tour does not sample the rest, so the national figure carries an editorial judgment for the remaining third of the crop.
While the online discussion has focused on the size of that corn gap, the historical record suggests it means less than it appears. Figure 1 shows the average difference between the Pro Farmer Crop Tour estimate and four USDA yield numbers from 2016 through 2025: the August, September, and October WASDE, and the final yield. On corn, the Tour sits below all four, and the gap narrows at every step, from 3.5 bushels against the August number to 2.3 bushels against the final. USDA moves toward the Tour as the season progresses, but never all the way. On soybeans, the same progression appears at a far smaller scale, running from 0.1 bushels below the August number to 0.4 bushels above the final.
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