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SATURDAY, OCTOBER 24, 2026   |   SPECIAL REPORT & ANALYSIS

SPECIAL REPORT  |  NASS CORN CORRECTION

NASS Corn Correction Rewrites September Baseline, Leaves October Forecast Intact

Higher Nebraska counts narrow the yield jump but leave process questions open

Jim Wiesemeyer  ·  Analysis  ·  October 24, 2026

USDA’s National Agricultural Statistics Service (NASS) finally corrected its September corn estimates Friday, Oct. 23, raising Nebraska’s yield and production forecasts, lowering Kansas’ forecasts and increasing the national September yield from 178.5 to 178.8 bushels per acre. The net production adjustment added 28.4 million bushels to September’s U.S. forecast.

The correction changes how the market should interpret the September-to-October increase. It does not change USDA’s current October forecast of 181.2 bushels per acre and 16.034 billion bushels of production. NASS said it reviewed and validated the October forecasts. Source: NASS notice.

The most consequential finding is in Nebraska’s underlying field data: September’s statewide ear count was understated by 2,050 ears per acre, while the separately published irrigated and nonirrigated counts were unchanged. Correcting that statewide figure eliminates the previously reported September-to-October increase in Nebraska ear counts. The corrected series instead shows a decline.

That helps explain why the original comparison looked anomalous. It also leaves an accountability question: What processing failure produced the incorrect statewide figures, and why did the agency’s checks fail to catch it before publication?

What NASS corrected: The agency identified a processing error affecting September plant populations, ear counts, yield and production for Kansas and Nebraska. The error also affected the 10-state population and ear-count averages and national yield and production.

NASS reissued both reports: the September report to correct the original forecasts and the October report to correct its September comparison columns. The September update identifies changes on pages 6, 26, 28, 31 and 32; the October update identifies pages 6, 32 and 33. NASS also updated Quick Stats. These are corrections to previously published September information, rather than new October crop forecasts. Source: NASS notice.

The national before-and-after comparison: Production below is in million bushels; yield is in bushels per harvested acre.

September measure	Originally published	Corrected Oct. 23	Change
U.S. corn yield	178.5	178.8	+0.3
U.S. corn production	15,799.759	15,828.159	+28.400
U.S. harvested acres, millions	88.506	88.506	None
10-state plants per acre	29,050	29,250	+200
10-state ears per acre	28,650	28,850	+200

Table 1. Sources: Original September Crop Production report and the Oct. 23 corrected September report; the corrected October report also republishes September yield and objective-yield figures. Original September report | Corrected September report (NASS notice).

The national production adjustment is about 0.18% of the original September forecast. That relatively small net change masks larger, offsetting state corrections: Nebraska added 48.05 million bushels, while Kansas lost 19.65 million.

Those changes reconcile directly with the unchanged harvested acreage:

Nebraska: 9.61 million acres × a 5-bushel yield increase = 48.05 million additional bushels.

Kansas: 6.55 million acres × a 3-bushel yield reduction = 19.65 million fewer bushels.

Net U.S. adjustment: +28.40 million bushels.

The published national yield is rounded to one decimal place. Consequently, multiplying the displayed 0.3-bushel adjustment by national acreage will not reproduce the exact production change.

All 10 states — September yield and production before and after: The “10 states” are the corn objective-yield states. Only Kansas and Nebraska had state-level corrections; the other eight states’ September figures were unchanged. Production is in million bushels.

Figure 1. The 10 corn objective-yield states; only Nebraska and Kansas September figures changed. Source: USDA NASS.

State	Orig. yield	Corr. yield	Yield chg.	Orig. prod.	Corr. prod.	Prod. chg.
Illinois	209.0	209.0	0	2,288.550	2,288.550	0
Indiana	200.0	200.0	0	1,032.000	1,032.000	0
Iowa	219.0	219.0	0	2,803.200	2,803.200	0
Kansas	121.0	118.0	−3.0	792.550	772.900	−19.650
Minnesota	195.0	195.0	0	1,618.500	1,618.500	0
Missouri	181.0	181.0	0	628.070	628.070	0
Nebraska	177.0	182.0	+5.0	1,700.970	1,749.020	+48.050
Ohio	194.0	194.0	0	626.620	626.620	0
South Dakota	145.0	145.0	0	846.800	846.800	0
Wisconsin	180.0	180.0	0	558.000	558.000	0

Table 2. Source: Comparison of page 6 in the original September report and corrected September report. These are September forecasts in both columns. Original yield = Orig.; corrected = Corr.; production in million bushels.

All 10 states — September plant populations and ear counts: These are counts per acre, not yields. The 10-state figures are NASS’s published regional averages.

State/region	Orig. plants	Corr. plants	Chg.	Orig. ears	Corr. ears	Chg.
Illinois	31,950	31,950	0	31,250	31,250	0
Indiana	29,450	29,450	0	28,850	28,850	0
Iowa	31,850	31,850	0	31,550	31,550	0
Kansas	22,000	21,250	−750	21,650	20,450	−1,200
Minnesota	31,450	31,450	0	31,700	31,700	0
Missouri	27,600	27,600	0	27,250	27,250	0
Nebraska—all corn	25,500	27,300	+1,800	25,000	27,050	+2,050
Ohio	30,400	30,400	0	30,050	30,050	0
South Dakota	26,900	26,900	0	26,100	26,100	0
Wisconsin	30,850	30,850	0	30,450	30,450	0
10-state average	29,050	29,250	+200	28,650	28,850	+200

Table 3. Sources: Original September report, pages 31–32; corrected September report, pages 31–32; corrected October report, pages 32–33. September report | October report.

Nebraska’s correction raised its September plant population 7.1% and ear count 8.2%.

Kansas’ corrections lowered those measures 3.4% and 5.5%, respectively.

Those are substantial changes in the underlying state indicators, even though they partly offset nationally.

Nebraska’s unchanged irrigation categories are central to the analysis: NASS corrected the “all corn” aggregation but left the September figures for each irrigation category intact.

Nebraska September measure	Original	Corrected	Change
Irrigated plants per acre	29,050	29,050	0
Nonirrigated plants per acre	25,100	25,100	0
Irrigated ears per acre	29,050	29,050	0
Nonirrigated ears per acre	24,550	24,550	0

Table 4. Source: September objective-yield tables and corrected October comparison tables. Crop Production reports.

Analysis: This pattern points toward a problem in how the statewide result was assembled or processed. It does not, by itself, establish that enumerators counted plants or ears incorrectly in the field.

An arithmetic illustration shows why the original Nebraska numbers attracted scrutiny. Combining the published irrigated and nonirrigated ear counts to reproduce the original statewide average implies an irrigated weight of approximately 10%. Reproducing the corrected statewide average implies approximately 56%.

Figure 2. Nebraska all-corn ears per acre against the unchanged irrigated and nonirrigated September counts. Source: USDA NASS.

Those are inferred mathematical weights, not verified percentages of sampled fields. The tables alone cannot establish the actual sample composition or identify the precise programming, weighting or processing error. NASS needs to explain that distinction explicitly.

How the correction changes the October story: The following comparisons hold October’s published figures constant and change only the September baseline.

Measure	Orig. Sept.	Corr. Sept.	Oct. (unch.)	Orig. Sept.–Oct.	Corr. Sept.–Oct.
U.S. yield, bu./acre	178.5	178.8	181.2	+2.7	+2.4
Nebraska yield, bu./acre	177.0	182.0	188.0	+11.0	+6.0
Kansas yield, bu./acre	121.0	118.0	125.0	+4.0	+7.0
Nebraska plants/acre	25,500	27,300	27,150	+1,650	−150
Nebraska ears/acre	25,000	27,050	26,700	+1,700	−350
Kansas ears/acre	21,650	20,450	20,500	−1,150	+50
10-state ears/acre	28,650	28,850	28,600	−50	−250

Table 5. Sources: Original and corrected Crop Production tables; changes calculated from published figures. Crop Production reports.

Figure 3. September-to-October yield change measured against the original and the corrected September baseline. Source: USDA NASS.

Three implications follow.

First, nearly half of Nebraska’s originally reported 11-bushel September-to-October yield increase disappears when the September baseline is corrected. Five bushels of the apparent increase reflected an understated earlier forecast.

Second, the apparent increase in Nebraska’s ear population disappears entirely. The corrected comparison shows 350 fewer ears per acre in October. Any remaining explanation for the state’s higher October yield must therefore address other yield evidence, including grain weight and producer-reported results, rather than rely on an increase in the published ear count.

Third, Kansas’ October yield rebound becomes larger, increasing from 4 to 7 bushels per acre. Correcting September does not uniformly reduce the size of the October changes.

NASS’s methodology combines field measurements with farmer survey information and statistical evaluation. Published ear counts are an important diagnostic, but they cannot independently reproduce or validate the official yield forecast. Source: Crop Production methodology section.

Market implications: The correction provides no mechanical reduction in the current supply outlook. October production remains 16,033.944 million bushels. Relative to the corrected September figure, the increase is 205.785 million bushels, compared with 234.185 million against the original September forecast.

That means the correction explains approximately 12% of the originally reported national production increase. Most of the increase remains.

Figure 4. U.S. corn production from original September to the unchanged October forecast, million bushels. Source: USDA NASS.

For farmers hoping the notice would reverse October’s larger crop estimate, that is a disappointing result. For analysts, however, the corrected baseline materially improves interpretation of the forecast sequence. Nebraska’s dramatic ear-count increase was an artifact of erroneous September data.

The correction also cannot undo marketing decisions already made using the original information. Its economic significance extends beyond the net 28.4-million-bushel adjustment: a faulty baseline can distort expectations, interpretations of crop development and assessments of subsequent reports.

Still, attributing a specific dollar amount of market losses solely to this error would require more evidence. Prices respond to the full supply-and-demand report, expectations before release and other developments.

Farmer reaction underscores the credibility problem: National Corn Growers Association President Matt Frostic called the error unacceptable and urged NASS to examine its procedures, prevent a recurrence and explain how it would rebuild confidence. “An error of this magnitude is unacceptable,” he said. Source: NCGA statement.

AgriTalk host and Farm Journal economist Chip Flory likewise emphasized the missing explanation. In AgWeb’s coverage, he welcomed acknowledgment of the error but questioned how it occurred and what NASS would do to prevent another one. Source: AgWeb.

What NASS still needs to explain: Observers say a useful technical follow-up should answer five questions:

What failed? Identify whether the error involved weighting, coding, classification, missing observations or another processing step.

Why these two states? Explain whether Kansas and Nebraska shared the same faulty procedure.

When was the problem discovered? Clarify whether October processing had already corrected the issue or whether the discrepancy was identified afterward.

What did October validation involve? Describe the independent checks supporting the unchanged forecast.

What safeguards are changing? Explain how future releases will detect inconsistent statewide aggregates before publication.

The notice does not establish that staffing shortages, enumerator inexperience or NASDA fieldwork caused the error. Those concerns warrant examination, but assigning responsibility requires evidence about the actual failure.

A former USDA official is not convinced: Asked about the notice, a former USDA official said the processing explanation does not rule out a fieldwork shortfall:

“I have no idea how to interpret NASS’s comment. If it was processing, does that include lack of enumerators? I suppose it could. I think the counts are too different for the ‘processing error’ to be that they were marked and processed as non-irrigated vs irrigated……so I’m still stuck with lack of enumeration….”

BOTTOM LINE

The central finding is now clear: The correction resolves an important Nebraska data inconsistency and substantially reduces the apparent monthly yield jump. It leaves October’s larger national crop forecast standing — and leaves NASS with the task of explaining how an error that affected market-sensitive forecasts passed through its publication controls. And why did it take so long for NASS to issue a correction?

AG POLICY & MARKETS DAILY   |   SPECIAL REPORT  |  NASS CORN CORRECTION — OCTOBER 24, 2026