It is the most basic of truisms to say that differences of opinion are required to make any market work successfully. The ups and downs of market prices reflect how those differences are weighted at any given point in time. Based on the price action of grain and soy futures markets over the past 12 months or so, there have been plenty of such differences reflected in the choppy price movements. If one could somehow remove the price impact of the South American drought -- which is impossible to do, of course -- it probably would not seem as though market price action reflected a gradually lower trend even though prices of grains and the soy complex chopped about in a rather wide price band.This is not to say that without the South American...