NASS Lowers Kansas September Corn Yield by 3 Bushels After Acreage Error

USDA's statistical agency has cut its corrected September corn yield forecast for Kansas to 119 bushels per acre, down 3 bushels, and raised Nebraska's to 182 bushels per acre, up 5, after finding a processing error that rippled through the national number. The corrected U.S. September forecast now stands at 178.8 bushels per acre, an increase of 0.3 bushels from the originally published figure.

The National Agricultural Statistics Service launched a review of its September and October corn estimation procedures after concerns were raised about the October 9 Crop Production report. The review traced the problem to September, not October.

What went wrong?

Bryan Combs, director of the Office of the Agricultural Statistics Board, said the September error involved incorrect acreage weights used to combine irrigated and nonirrigated objective yield observations for Kansas and Nebraska. The mistake affected September corn plant populations and ear counts in both states and in the 10-state averages, as well as yield forecasts for the two states and the nation as a whole.

NASS has corrected the affected September data and forecasts in its Crop Production reports and in the Quick Stats database. The agency also reviewed and validated the October data and estimation procedures, and confirmed the October yield and production forecasts remain unchanged.

That distinction matters for market watchers. The September figures were forecasts built from objective yield surveys, not harvested results. The October numbers, which survived scrutiny, now carry the agency's full weight of confirmation.

What changes for growers?

The practical question is confidence. Corn growers say the error has already cost them real money, and they want answers before the next planting season locks in input decisions.

Matt Frostic, a Michigan farmer and president of the National Corn Growers Association, released a statement tying the reports directly to farm margins. "Recent reports by NASS have cost corn growers billions of dollars in market value, at a time when profit margins were already marginal, at best, and the cost for fuel and other inputs are at all-time highs," Frostic said. "Corn prices dropped in conjunction with the release of recent reports and have only continued to drop."

He called an error of this magnitude unacceptable and said it further erodes farmer confidence in the agency's ability to produce statistically sound and accurate reports. Frostic pressed NASS to seriously examine the processes that led to the mistake, take immediate action to prevent a repeat, and meet with growers to explain how the service intends to rebuild trust.

What NASS plans next

Combs said the agency is acting on both process and prevention. "Moving forward, we will implement additional pre-publication checks to verify acreage weights and validate objective yield calculations," Combs said. "We are evaluating further improvements to strengthen our quality-control procedures."

He also acknowledged the role of outside scrutiny in catching the problem. "We thank the farmers and data users who brought the concerns to our attention," Combs said. "NASS remains committed to providing timely, accurate, and reliable agricultural statistics and to promptly communicating and correcting any errors identified in our published data."

The episode underscores a structural reality of the corn market: a single misapplied weight in two Plains states moved the national yield forecast, and with it the price signals that guide billions of dollars in grain marketing, basis setting and input purchasing decisions across the Corn Belt. With October forecasts confirmed and quality-control upgrades under evaluation, the next test of NASS credibility arrives with the agency's subsequent reports, where growers and data users will be watching the numbers closely.