The change in the exchange rate relative to the dollar is currently greatest for the Brazilian real and the Argentine peso. The only other currency that comes even close is the Russian ruble. Relative currency valuation is a major factor in export competitiveness. The U.S., Argentina and Brazil have roughly the same trade to GDP ratios, but Latin American exports are about six times more sensitive to exchange rate fluctuations than those from the U.S. due to the latter’s role as a reserve currency.  Farmers in Argentina and Brazil are taking advantage of the outsized lower value of the national currencies by forward selling their production. One impact of this surge in exports is an increase in U.S. carryover stocks relative to...