What needs to happen to get a flood of grain moving?
South America apparently is going to produce a crop.
Parts are better than last year.
Parts are worse than last year.
On the whole, South America will be exporting something soon.
Maybe low River levels slowed some exports?
Maybe low water levels in Panama has slowed some exports? 
Maybe farmers have not been selling as much?
Maybe a stronger dollar has limited exports?
Somehow, in the Winter, if farmers quit selling the price goes down.
Somehow, in the middle of the Summer, if farmers quit selling the price goes up.
We are almost out of the drought,
Parts of Iowa are still in the drought.
What next?
When do the February lows bottom out?