NASS just admitted a processing error in its September 2026 Crop Production report that skewed corn data for Kansas and Nebraska. The mistake used incorrect acreage weights when combining irrigated and non-irrigated objective yield observations. That threw off plant populations, ear counts, yields, and production figures for those two states, the 10-state averages, and the U.S. totals.
Corrected September numbers show Kansas yield at 119 bushels per acre (down 3 from the original), Nebraska at 182 (up 5), and the national average at 178.8 (up 0.3). Production rose by about 28 million bushels in the revision. NASS reviewed the October 9 forecasts and left them unchanged at 181.2 bushels per acre and roughly 16.03 billion bushels of production. The jump from September to October now looks like 2.4 bushels instead of the original 2.7.
How did they get it so wrong? A straightforward weighting error on irrigated versus non-irrigated samples in two key states slipped through. Concerns after the big October surprise, especially the 11-bushel Nebraska increase that helped drive the national jump, forced a review. NASS says it will add extra pre-publication checks on acreage weights and objective yield calculations going forward.
The market impact was immediate and brutal. The October report, coming on top of the flawed September baseline, crushed corn prices. December futures hit the 30-cent limit down at one point and closed nearly 22 cents lower. Prices kept sliding afterward. National Corn Growers Association president Matt Frostic said recent NASS reports cost corn growers billions in market value while margins were already tight and input costs remained high.
For producers, the correction means the October number still stands as the official forecast, so the big crop signal and lower price pressure remain. Confidence in NASS data took another hit at a time when farmers need reliable numbers for marketing and risk decisions. Frostic called the error unacceptable and said the agency must examine its processes and rebuild trust. Growers will watch the next reports closely as harvest data comes in and look for clearer communication from USDA.