Quarterly Grain Stocks - Corn

Quarterly Grain Stocks - Corn is the corn section of the Grain Stocks report from USDA NASS (National Agricultural Statistics Service). It measures physical corn in storage, in bushels, on one reference date each quarter. The total covers on-farm inventory plus off-farm inventory in commercial storage such as elevators and processors. It does not measure production, yield, acreage, prices, or demand directly.

Reference dates are March 1, June 1, September 1, and December 1, with collection lasting about 15 calendar days starting up to two days early. Regional offices edit results for about 4 to 5 business days. Then the national board reviews estimates for 5 to 6 business days.

The report appears at month end, except December 1 estimates, which appear in January with the Crop Production Annual Summary. Release time is 12:00 p.m. Eastern since January 11, 2013, after 8:30 a.m. before that.

Estimates can be revised next quarter, again the next January, and every 5 years after the Census of Agriculture when new information arrives. The publisher states no thresholds or targets. Markets read the level against analyst expectations, so a high surprise signals weaker use and pressures prices.

Headline corn stocks move with farm-held supply, commercial supply, and implied quarterly use.

• Total corn stocks: all old-crop and new-crop corn in US storage on the reference date.
• On-farm stocks: corn stored on farms, capturing producer-held inventory that farmers can sell later.
• Off-farm stocks: corn in mills, elevators, warehouses, terminals, and processors, capturing commercial pipeline inventory.
• Indicated disappearance: implied quarterly use, including exports, crush, food, feed, seed, and ethanol, with feed and residual the most uncertain part.
• Production-revision block: revised prior-year area, yield, and grain and silage output in September releases, reconciling the finished marketing year.

The September 1, 2023 example, released September 29, 2023, put old-crop stocks at 1.36 billion bushels, down 1% from a year earlier. On-farm stocks rose 19% to 605 million bushels, while off-farm stocks fell 13% to 756 million bushels. June to August indicated disappearance was 2.75 billion bushels, below 2.97 billion a year earlier, and the revision cut 2022 output by 15.0 million bushels. The lesson is that a flat headline can hide opposing moves, and stocks can correct production.

1. Sample and enumerate: NASS surveys farms for on-farm stocks and contacts every known commercial store for off-farm stocks. The farm sample uses multivariate probability proportional to size sampling, with a panel tracking quarterly change.
2. Collect: Questionnaires ask storage capacity and stocks on the reference date, with large firms reporting per site or by state.
3. Edit and impute: Automated checks fix inconsistencies. Missing farms are filled from prior-quarter ratios or similar farms, and missing commercial stores from capacity ratios.
4. Expand: Responses are weighted up to totals, while change ratios track quarter-to-quarter moves from reported data only. The report shows raw levels with no seasonal adjustment and no index weighting.
5. Review and check: Regional offices propose state figures, and the national board sets US totals first by consensus. States are then reconciled to the national total and checked against trade and use data.
6. Publish and derive disappearance: The published total is on-farm plus off-farm stocks, and quarterly disappearance is starting stocks plus production plus imports minus ending stocks. For June to August, with no new output, it is June 1 minus September 1 stocks: 4,107,309 minus 1,361,303 thousand bushels equals about 2.75 billion.