Last I checked, ADM wasn’t a corn producer. They are shysters that buy their grain from producers and sell to users. Not only do they have the motive to influence grain markets, they are large enough to do so. Given their political contributions, no Federal decision concerning grain can be considered clean.
How do you think ADM influences the corn market?
The USDA is not part of the political structure, so there is no such thing as a "political contribution" to anybody in that agency. Any "contribution" would be considered a BRIBE. And ADM would have to bribe all the folks involved in the data collection process, down to below the level of county agent, and trust that NONE of them would "squeal". We're talking about the validity of the statistics gathered by the USDA---not a vote by Congress.