Processing error affected September corn yield and production estimates for Kansas, Nebraska and the United States, prompting calls from corn growers for greater accuracy and accountability.
A correction to U.S. Department of Agriculture corn estimates is drawing sharp criticism from corn growers at a time when crop prices and farm margins are already under pressure.
The USDA National Agricultural Statistics Service (NASS) announced October 23 that it had corrected data in its September 2026 Crop Production report after identifying a processing error affecting corn plant populations, ear counts, yields and production estimates for Kansas and Nebraska.
The error also affected 10-state averages for plant populations and ear counts, as well as the national corn yield and production forecasts.
NASS said the affected September figures have been corrected in its Crop Production reports and Quick Stats database.
Importantly for farmers and grain markets, the agency said the October forecasts released October 9 were reviewed and validated and have not changed.
Revised September Estimate Puts U.S. Corn at 15.8 Billion Bushels
The corrected September Crop Production report forecasts U.S. corn production for grain at 15.8 billion bushels, down 1 percent from the previous forecast and 7 percent below 2025.
The revised national average yield is 178.8 bushels per acre, 1.9 bushels below the previous forecast and 7.7 bushels below 2025.
Despite the year-over-year decline, NASS said the September production forecast, if realized, would represent the second-highest U.S. corn crop on record.
The correction specifically changed September corn yield and production forecasts for Kansas, Nebraska and the United States. NASS also revised corn-for-grain plant population figures for Kansas and Nebraska and the 10-state region, along with ear-count estimates for those areas.
October Corn Forecast Remains Unchanged
The correction does not mean USDA has revised its current October outlook.
NASS said it reviewed and validated the October forecasts published October 9 and made no changes to those figures.
The October Crop Production report forecasts U.S. corn production at 16.0 billion bushels, 1 percent higher than the previous forecast but 5 percent below 2025.
Average U.S. corn yield in the October report is forecast at 181.2 bushels per acre, an increase of 2.4 bushels from the previous forecast but 5.3 bushels below last year.
That distinction is significant for growers following the reports: the processing problem required corrections to the September data, while USDA says its newer October estimates remain valid.
Corn Growers Say Error Damaged Farmer Confidence
The National Corn Growers Association (NCGA) responded strongly to the correction.
NCGA President Matt Frostic, a Michigan farmer, said recent NASS reports had cost corn growers billions of dollars in market value and argued that the error comes at an especially difficult time for producers dealing with tight margins and high input costs.
Frostic called the mistake unacceptable and said it further erodes farmer confidence in the agency's ability to produce accurate agricultural statistics.
NCGA is calling on NASS to examine the processes that allowed the mistake to occur and take action to prevent similar problems.
The association also wants to meet with the agency to discuss how NASS plans to improve its processes and rebuild growers' confidence in its reports.
Corn Prices Already a Concern for Growers
The issue over USDA crop estimates comes against a challenging economic backdrop for corn producers.
Following the October 9 USDA World Agricultural Supply and Demand Estimates report, NCGA noted that USDA had increased its anticipated 2026 corn yield by 2.7 bushels per acre and that corn prices fell immediately after the report was released.
At the time, Frostic pointed to high diesel and fertilizer costs as additional pressures on farm budgets and urged Congress to advance policies designed to increase corn demand.
That makes confidence in government crop estimates particularly important. USDA reports can quickly influence expectations about crop supplies and the outlook for commodity markets, while producers are making marketing and financial decisions for their operations.
Why the NASS Correction Matters to Corn Farmers
The immediate statistical issue is confined to the September estimates, but the grower response highlights a broader concern about confidence in agricultural data.
Corn farmers rely on USDA information alongside market prices, local basis levels, production costs and their own yield expectations when making marketing and business decisions.
NASS describes its role as providing meaningful, accurate and objective statistical information to U.S. agriculture. Following the October 23 correction, corn growers are now looking for more detail on what the agency will do to prevent another processing error.
For farmers watching the market, the most important point is that USDA's October 9 corn forecast remains unchanged at 16.0 billion bushels and 181.2 bushels per acre.
The larger question raised by the correction is whether NASS can restore grower confidence in one of the agricultural industry's most closely watched sources of crop information.