The U.S. Department of Agriculture corrected its September 2026 corn production estimates after identifying an error in how irrigated and non-irrigated observations from Nebraska and Kansas were combined. The revision changed reported plant populations, ear counts, yields and production for the two states and altered the national estimate.
The USDA’s National Agricultural Statistics Service announced the correction on Oct. 23, following questions about the difference between its September and October corn estimates. In a follow-up notice on Oct. 24, the agency said incorrect acreage weights had been used when combining the irrigated and non-irrigated observations.
The correction increased the national September corn production forecast by 28.4 million bushels. That reduced the reported increase between the September and October production forecasts by about 12%. NASS also revised state-level yields and production figures and adjusted the 10-state objective-yield averages used in the estimates.
What USDA changed
- The error affected September plant-population and ear-count calculations in Nebraska and Kansas.
- State yield and production estimates were revised after the acreage weights were corrected.
- NASS reviewed its October calculations and left the October forecasts unchanged.
USDA crop estimates provide a common set of figures for farmers, grain buyers and other participants in the agricultural market. The figures are used in price discovery, marketing decisions and risk management. Revisions that move national production totals can also change how market participants interpret the size of the crop.
Two USDA reports in late September and October were followed by large one-day declines in December corn futures. On Sept. 30, December corn futures fell 21.25 cents per bushel after USDA reported Sept. 1 corn stocks of 2.095 billion bushels, above market expectations of about 1.924 billion bushels. On Oct. 9, the contract fell another 20.5 cents.
The revised September production figure illustrates how state-level survey calculations can affect national crop totals. Nebraska is among the major corn-producing states whose irrigated and non-irrigated acreage observations are incorporated into USDA’s estimates, making the accuracy of those weights relevant to the state’s reported yields and production as well as the national totals.
USDA said the October forecasts remained unchanged after the agency reviewed the calculations. The corrected September figures now provide the revised baseline for comparisons with the October estimate.
