How grain and soy markets react to their own set of uncertainties often ignores what financial markets may be doing.Uncertainty almost always leads to volatility for the world's financial and commodity markets. We have seen this truism demonstrated once again during the last 10 days, culminating with yesterday's "crash and burn" action of world stock markets. The Shanghai Composite Index fell 8.5 percent, while Japanese and European stock markets dropped as much as 5 percent. After a wild day that had it down 1,000 points in early trading, the Dow recovered most of that before slumping again to close down 588 points or 3.6 percent. The S&P 500 lost 3.9 percent.Today the Shanghai Index dropped 7.6 percent. However, China's central bank r...