U.S. Government Inspection and Grading
Purpose
Global corn supply chains need verifiable, predictable and consistent oversight measures that fit the diverse needs of all end users. Oversight measures, implemented through standardized inspection procedures and grading standards, are established to provide:
Information for buyers about the quality of grain at the time of loading for transport to the buyer; and
Food and feed safety protection for the end users.
The United States is recognized globally as having a combination of official grades and standards that are typically used for exporting grains and referenced in export contracts. U.S. corn sold by grade and shipped for foreign commerce must be officially inspected and weighed by the USDA Federal Grain Inspection Service (FGIS) or an official service provider delegated or designated by FGIS to do so (with a few exceptions). In addition, all corn exports must be tested for aflatoxins, unless the contract specifically waives this requirement. Qualified state and private inspection agencies are permitted to be designated by FGIS as official agents to inspect and weigh corn at specified interior locations. In addition, certain state inspection agencies can be delegated by FGIS to inspect and weigh grain officially at certain export facilities. Supervision of these agencies’ operations and methodologies is performed by FGIS field office personnel.
Inspection and Sampling
The loading export elevator provides FGIS or the delegated state inspection agency a load order specifying the quality of the corn to be loaded as designated in the export contract. The load order specifies the U.S. grade, moisture content and all other requirements which have been agreed upon in the contract between the foreign buyer and the U.S. supplier, plus any special requirements requested by the buyer, such as minimum protein concentration, maximum moisture content or other special requirements. The official inspection personnel determine and certify that the corn loaded in the vessel or railcar meets the requirements of the load order. Independent laboratories can be used to test for quality factors not mandated to be performed by FGIS, or for which FGIS does not have the local ability to test.
Shipments or “lots” of corn are divided into “sublots.” Representative samples for grading are obtained from these sublots using a diverter sampling device approved by FGIS. This device takes a primary portion approximately every 200 to 500 bushels (about 5.1 to 12.7 metric tons) from the moving grain stream just after the final elevation before loading into the vessel, shipping bin or railcar. The primary portions are usually further reduced by a secondary sampler, and incremental portions are combined by sublot and inspected by licensed inspectors. The results are entered into a log, and typically a statistical loading plan is applied to ensure not only that the average result for each factor meets the contract specifications, but also to ensure the lot is reasonably uniform in quality. Any sublot that does not meet uniformity criteria on any factor must be returned to the elevator or certified separately. The average of all sublot results for each factor is reported on the final official certificate. The FGIS sampling method provides a truly representative sample, while other commonly used methods may yield non-representative samples of a lot due to the uneven distribution of corn in a truck, railcar or in the hold of a vessel.
Grading
Yellow corn is divided into five U.S. numerical grades and U.S. Sample Grade. Each grade has limits for test weight, broken corn and foreign material (BCFM), total damaged kernels and heat-damaged kernels as a subset of total damage. The limits for each grade are summarized in the table shown in the “U.S. Corn Grades and Conversions” section found on page 66 of this report. In addition, FGIS provides certification of moisture content and aflatoxin results. Export contracts for corn can also specify other conditions or attributes related to the cargo, if requested, such as stress cracks, protein or oil concentrations and other mycotoxin results. In some cases, independent labs are used to conduct tests not required by FGIS.
Since the limits on all official grade factors (such as test weight and total damage) cannot always be met simultaneously, some grade factors may be better than the limit for a specified grade, but they cannot be worse. For that reason, most contracts are written as “U.S. No. 2 or better” or “U.S. No. 3 or better.” This permits some grade factor results to be at or near the limit for that grade, while other factor results are “better than” that grade.