Why Such Corn Market Swings?

David Kotok on the USDA reports:

In the last few weeks, we have watched the roller-coaster reports on the corn harvest from the US Department of Agriculture. During the last month, they were very bullish, and then they were bearish, and then they were bullish. To quote our friend Dennis Gartman, “Reflecting the uncertainty of the report and the skepticism with which the numbers have been received,” the USDA has issued a clarifying statement saying they may issue a clarifying statement. It will be released on August 11. Until then, “Confusion will reign,” says Dennis.......
GIC board member Michael Drury noted that the “government numbers assumed an average year for acres harvested.” Michael is a personal friend and chief economist at McVean Trading, one of the premier private grain and livestock futures trading operations in the United States. He added that “There are 6 million acres in North and South Dakota where flooding has been severe.” They were planted late (or maybe not at all), but the driving force (Kotok’s view) may have been to collect insurance claims. The crop yield from these late plantings may be insignificant.
There is also controversy about the inventory numbers. And about what the foreign holdings of corn reveal or do not reveal. And there is the distortion that continues because of ethanol subsidies and mandated use, which directs as much as 40% of the corn crop into fuel instead of food. This persists while American policy practices protectionism, so sugar ethanol is not imported. It is much less costly than corn ethanol.
Okay, enjoy the ear of corn on the Fourth of July. And the beef and chicken and other foods that depend on America’s grains. Try to remember that American policy is now starving millions of people in the world because we are driving food prices ever higher. Perhaps we can think about that as we watch presidential candidates genuflect to Iowans. Perhaps, those candidates who are skipping the Iowa caucuses deserve more of our respect. Time will tell.

I wouldn't assume those acres were planted only to collect insurance, as they might have been paid out for prevented planting.  In all likelihood, they needed feed grain or grain they had already contracted.  Plus, all farmers seem to share an optimism that if they just can get the corn planted, the weather will quit hurting them and will help them out.  If I remember correctly, the Dakotas were putting out more corn than normal this year, but their historical yields aren't tremendously good anyway.  I wouldn't be surprised by a significant yield miss by USDA this year, but I'd like to know who has better numbers.  As for the issues with ethanol and the food supply, I agree with him.