News that the U.S. and the EU pulled back from a potentially escalating trade war gave financial markets a boost late yesterday, and the agreements between President Trump and EU President Juncker included a promise that the EU would buy more U.S. soybeans. Algorithmic trading programs read the headlines, and their buying helped push soybean futures higher by double digits in overnight trade. President Trump said that the EU agreed to “buy a lot of soybeans,” but there was no effort to quantify what that meant. In fact, President Juncker cannot direct the purchases of numerous private EU oilseed processors. Limited Argentine supplies and the China-driven premium for Brazilian soybeans mean the EU has to buy more from the U.S. no...