Good points, but I'm a simple guy. I like to stick to the things I can point to with some real assurance. That's part of what's so great about commodities investing - you're making bets on stuff, not just opinions and potential.

So when I see the kind of action we've seen in corn this summer, I am inclined to think there's something going on that's a bit more than just investor sentiment. Here's how it's gone lately:

So let's recap: This summer we had a huge run-up to $7.50/bushel in corn based almost entirely on a theoretical supply shock. Iowa briefly became a destination for boaters as millions of acres went under water from floods. The headlines at the time (in June) were predictably hyperbolic, prices spiked as traders bet against the character and ingenuity of Iowa farmers, and then, as Don Bousquet covered in July, the USDA dropped a surprise on the markets: Those crafty farmers had actually sewn a million or so more acres than previously thought. Supply shock over, the market then turned to the demand side, and saw the effect of the Corn Crush Squeeze that Brad highlighted last week.

And so, late summer has been a strictly "look out below" affair. Until last week, when corn started gobbling back pennies 25 at a time. So, why the pop?

First off, corn is at a critical point. The meme du jour is that ethanol's a bust, so that's bad for corn bulls. And weather is showing even more mixed signals now. July's good news for buyers - that the crops were just fine - was supported by the mid-August crop report from the USDA, which suggested farmers would be harvesting 79.3 million acres, pretty much in line with most analysts' expectations.